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industrial i/v output driver, single-supply, 55 v maximum supply, programmable ranges ad5751 rev. a information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. specifications subject to change without notice. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective owners. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781.329.4700 www.analog.com fax: 781.461.3113 ?2009-2010 analog devices, inc. all rights reserved. features current output ranges: 0 ma to 20 ma, 0 ma to 24 ma, or 4 ma to 20 ma 0.03% fsr typical total unadjusted error (tue) 5 ppm/c typical output drift 2% overrange voltage output ranges: 0 v to 5 v, 0 v to 10 v, 0 v to 40 v 0.02% fsr typical total unadjusted error (tue) 3 ppm/c typical output drift overrange capability on all ranges flexible serial digital interface on-chip output fault detection pec error checking asynchronous clear function power supply range av dd : 12 v ( 10%) to 55 v (maximum) output loop compliance to av dd ? 2.75 v temperature range: ?40c to +105c 32-lead 5 mm 5 mm lfcsp package applications process control actuator control plcs general description the ad5751 is a single-channel, low cost, precision, voltage/ current output driver with hardware or software programmable output ranges. the software ranges are configured via an spi-/ microwire?-compatible serial interface. the ad5751 targets applications in plc and industrial process control. the analog input to the ad5751 is provided from a low voltage, single-supply digital-to-analog converter (dac) and is internally conditioned to provide the desired output current/voltage range. the output current range is programmable across three current ranges: 0 ma to 20 ma, 0 ma to 24 ma, or 4 ma to 20 ma. voltage output is provided from a separate pin that can be configured to provide 0 v to 5 v, 0 v to 10 v, and 0 v to 40 v output ranges. an overrange is available on the voltage ranges. analog outputs are short-circuit and open-circuit protected and can drive capacitive loads of 1 f and inductive loads of 0.1 h. the device is specified to operate with a power supply range from 10.8 v to 55 v. output loop compliance is 0 v to av dd ? 2.75 v. the flexible serial interface is spi and microwire compatible and can be operated in 3-wire mode to minimize the digital isolation required in isolated applications. the interface also features an optional pec error checking feature using crc-8 error checking, useful in industrial environments where data communication corruption can occur. the device also includes a power-on reset function ensuring that the device powers up in a known state (0 v or tristate) and an asynchronous clear pin that sets the outputs to zero- scale/midscale voltage output or the low end of the selected current range. an hw select pin is used to configure the part for hardware or software mode on power-up. table 1. related device part number description ad5422 single-channel, 16-bit, serial input current source and voltage output dac
ad5751 rev. a | page 2 of 32 table of contents features .............................................................................................. 1 ? applications ....................................................................................... 1 ? general description ......................................................................... 1 ? revision history ............................................................................... 2 ? functional block diagram .............................................................. 3 ? specifications ..................................................................................... 4 ? timing characteristics ................................................................ 7 ? absolute maximum ratings ............................................................ 9 ? esd caution .................................................................................. 9 ? pin configuration and function descriptions ........................... 10 ? typical performance characteristics ........................................... 12 ? current output ........................................................................... 15 ? terminology .................................................................................... 20 ? theory of operation ...................................................................... 21 ? software mode ............................................................................ 21 ? currrent output architecture .................................................. 23 ? driving inductive loads ............................................................ 23 ? power-on state of the ad5751 ................................................ 23 ? default registers at power-on ................................................. 24 ? reset function ............................................................................ 24 ? outen ........................................................................................ 24 ? software control ........................................................................ 24 ? hardware control ...................................................................... 26 ? transfer function ....................................................................... 26 ? detailed description of features .................................................. 27 ? output fault alertsoftware mode ....................................... 27 ? output fault alerthardware mode ..................................... 27 ? voltage output short-circuit protection ................................ 27 ? asynchronous clear (clear) ................................................. 27 ? external current setting resistor ............................................ 27 ? programmable overrange modes ............................................ 28 ? packet error checking ............................................................... 28 ? applications information .............................................................. 29 ? transient voltage protection .................................................... 29 ? thermal considerations ............................................................ 29 ? layout guidelines....................................................................... 30 ? galvanically isolated interface ................................................. 30 ? microprocessor interfacing ....................................................... 30 ? outline dimensions ....................................................................... 31 ? ordering guide .......................................................................... 31 ? revision history 5/10rev. 0 to rev. a changes to table 2, power requirements ..................................... 6 10/09revision 0: initial version
ad5751 rev. a | page 3 of 32 functional block diagram clear vsense+ vout d v cc gnd a v dd gnd comp1 comp2 clrsel hw select vin vref overtemp vout short fault iout open fault reset r2 r set avdd r3 ad5751 07269-001 iout * denotes shared pin. software mode denoted by regular text, hardware mode denoted by italic text. for example, for fault/ temp pin, in software mode, this pin takes on fault function. in hardware mode, this pin takes on temp function. power- on reset iout open fault iout range scaling status register vout short fault vout range scaling input shift register and control logic sclk/ outen * sdin/ r0 * sync/ rset * sdo/ vfault * fault/ temp * nc/ ifault * ad2/ r1 * ad1/ r2 * ad0/ r3 * rext1 rext2 figure 1. functional block diagram
ad5751 rev. a | page 4 of 32 specifications av dd = 12 v ( 10%) to 55 v (maximum), dv cc = 2.7 v to 5.5 v, gnd = 0 v. iout: r load = 300 . all specifications t min to t max , unless otherwise noted. table 2. parameter 1 min typ max unit test conditions/comments input voltage range output unloaded 0 to 4.096 v input leakage current ?1 +1 a reference input reference input voltage 4.096 v external reference must be exactly as stated; otherwise, accuracy errors show up as error in output input leakage current ?1 +1 a voltage output output voltage ranges 0 5 v 0 10 v avdd must have minimum 1.3 v headroom or >11.3 v 0 40 v output voltage overranges 2 0 6 v programmable overranges; see detailed description of features section 0 12 v 0 44 v accuracy total unadjusted error (tue) b version 3 ?0.1 +0.1 % fsr ?0.05 0.02 +0.05 % fsr t a = 25c a version 3 ?0.3 +0.3 % fsr ?0.1 0.05 +0.1 % fsr t a = 25c relative accuracy (inl) ?0 .02 0.005 +0.02 % fsr dead band on output, rti ?14 8 +14 mv referred to 4.096 v input range offset error ?5 +5 mv 0 v to 10 v range ?4 0.5 +4 mv t a = 25c, 0 v to 10 v range ?3 +3 mv 0 v to 5 v range ?2.2 0.3 +2.2 mv t a = 25c, 0 v to 5 v range ?20 +20 mv 0 v to 40 v range ?17 0.5 +17 mv t a = 25c, 0 v to 40 v range gain error ?0.05 +0.05 % fsr 0 v to 5 v, 0 v to 10 v range ?0.04 0.015 +0.04 % fsr t a = 25c ?0.09 +0.09 % fsr 0 v to 40 v range ?0.05 0.02 +0.05 % fsr t a = 25c gain error tc 4 0.5 ppm fsr/c all ranges full-scale error ?0.05 +0.05 % fsr 0 v to 5 v, 0 v to 10 v range ?0.04 0.015 +0.04 % fsr t a = 25c ?0.09 +0.09 % fsr 0 v to 40 v range ?0.05 0.02 +0.05 % fsr t a = 25c full-scale error tc 4 1.5 ppm fsr/c all ranges output characteristics 4 headroom 1.3 v output unloaded short-circuit current 15 ma load 1 k for specified performance, 0 v to 5 v and 0 v to 10 v ranges 5 k for specified performance, 0 v to 40 v range
ad5751 rev. a | page 5 of 32 parameter 1 min typ max unit test conditions/comments capacitive load stability t a = 25c r load = 1 nf r load = 1 k 1 nf r load = 2 f external compensation capacitor required; see driving large capacitive loads section dc output impedance 0.12 settling time 0 v to 5 v range, ? to ? step 7 s specified with 2 k || 220 pf, 0.05% 0 v to 5 v range, 40 mv input step 4.5 s specified with 2 k || 220 pf, 0.05% 0 v to 40 v range, ? to ? step 15.8 s specified with 5 k || 220 pf, 0.05% slew rate 2 v/s specified with 1 k || 220 pf output noise 3.5 v rms 0.1 hz to 10 hz bandwidth 45.5 v rms 100 khz bandwi dth; specified with 2 k || 220 pf output noise spectral density 165 nv/hz measured at 10 khz; specified with 2 k || 220 pf ac psrr 65 db 200 mv, 50 hz/60 hz sine wave superimposed on power supply voltage dc psrr 10 v/v current output output current ranges 0 24 ma 0 20 ma 3.92 20 ma output current overranges 2 0 24.5 ma see detailed description of features section 0 20.4 ma see detailed description of features section 3.92 20.4 ma see detailed description of features section accuracy (internal r set ) total unadjusted error (tue) b version 3 ?0.2 +0.2 % fsr ?0.08 0.03 +0.08 % fsr t a = 25c a version 3 ?0.5 +0.5 % fsr ?0.3 0.15 +0.3 % fsr t a = 25c relative accuracy (inl) ?0 .02 0.01 +0.02 % fsr offset error ?16 +16 a ?10 +5 +10 a t a = 25c offset error tc 4 3 ppm fsr/c dead band on output, rti 8 +14 mv referred to 4.096 v input range gain error ?0.2 +0.2 % fsr ?0.125 0.02 +0.125 % fsr t a = 25c gain tc 4 10 ppm fsr/c full-scale error ?0.2 +0.2 % fsr ?0.125 0.02 +0.125 % fsr t a = 25c full-scale tc 4 4 ppm fsr/c accuracy (external r set ) total unadjusted error (tue) b version 3 ?0.1 +0.1 % fsr ?0.08 0.03 +0.08 % fsr t a = 25c a version 3 ?0.3 +0.3 % fsr ?0.1 0.02 +0.1 % fsr t a = 25c relative accuracy (inl) ?0.02 0.01 +0.02 % fsr offset error ?14 +14 a ?11 +5 +11 t a = 25c offset error tc 4 2 ppm fsr/c dead band on output, rti 8 +14 mv referred to 4.096 v input range gain error ?0.08 +0.08 % fsr ?0.07 0.02 +0.07 % fsr t a = 25c
ad5751 rev. a | page 6 of 32 parameter 1 min typ max unit test conditions/comments gain tc 4 1 ppm fsr/c full-scale error ?0.1 +0.1 % fsr ?0.07 0.02 +0.07 % fsr t a = 25c full-scale tc 4 2 ppm fsr/c output characteristics 4 current loop compliance voltage 0 av dd ? 2.75 v resistive load chosen such that compliance is not exceeded inductive load see test conditions/comments colu mn h needs appropriate capacitor at higher inductance values; see driving inductive loads section settling time 4 ma to 20 ma, full-scale step 8.5 s 250 load 120 a step, 4 ma to 20 ma range 1.2 s 250 load dc psrr 1 a/v output impedance 130 m digital inputs 4 jedec compliant input high voltage, v ih 2 v input low voltage, v il 0.8 v input current ?1 +1 a per pin pin capacitance 5 pf per pin digital outputs 4 fault, ifault, temp, vfault v ol , output low voltage 0.4 v 10 k pull-up resistor to dvcc 0.6 v at 2.5 ma v oh , output high voltage 3.6 v 10 k pull-up resistor to dvcc sdo v ol , output low voltage 0.5 0.5 v sinking 200 a v oh , output high voltage dvcc ? 0.5 dvcc ? 0.5 v sourcing 200 a high impedance output capacitance 3 pf high impedance leakage current ?1 +1 a power requirements av dd 10.8 55 v dv cc input voltage 2.7 5.5 v ai dd 4.4 5.6 ma output unloaded, output disabled 5.2 6.2 ma current output enabled 5.2 6.2 ma voltage output enabled di cc 0.3 1 ma v ih = dvcc, v il = gnd power dissipation 108 mw avdd = 24 v, outputs unloaded 1 temperature range: ?40c to +105c; typical at +25c. 2 overranges are nominal; gain and offset are not trimmed as per nominal ranges. 3 specification includes gain and offset errors, over temper ature, and drift after 1000 hours, t a = 125c. 4 guaranteed by characterization, but not production tested.
ad5751 rev. a | page 7 of 32 timing characteristics av dd = 12 v ( 10%) to 55 v (maximum), dv cc = 2.7 v to 5.5 v, gnd = 0 v. vout: r load = 2 k (5 k for 0 v to 40 v range), c l = 200 pf, iout: r load = 300 . all specifications t min to t max , unless otherwise noted. table 3. parameter 1 , 2 limit at t min , t max unit description t 1 20 ns min sclk cycle time t 2 8 ns min sclk high time t 3 8 ns min sclk low time t 4 5 ns min sync falling edge to sclk falling edge setup time t 5 10 ns min 16 th sclk falling edge to sync rising edge (on 24 th sclk falling edge if using pec) t 6 5 ns min minimum sync high time (write mode) t 7 5 ns min data setup time t 8 5 ns min data hold time t 9 , t 10 1.5 s max clear pulse low/high activation time t 11 5 ns min minimum sync high time (read mode) t 12 40 ns max sclk rising edge to sdo valid (sdo c l = 15 pf) t 13 10 ns min reset pulse low time 1 guaranteed by characterization, but not production tested. 2 all input signals are specified with t r = t f = 5 ns (10% to 90% of dv cc ) and timed from a voltage level of 1.2 v. timing diagrams d15 12 16 d0 t 1 t 2 t 5 t 8 t 7 t 3 sclk sync sdin clear vout t 10 t 9 t 13 reset t 4 t 6 07269-003 figure 2. write mode timing diagram
ad5751 rev. a | page 8 of 32 t 11 t 12 a2 sdin sync sclk a0 r = 1 0 x x x x x x x x x x x a1 x sdo x x x r3 r2 r1 r0 clrsel outen rset pec error over temp iout fault vout fault x 07269-004 figure 3. readback mode timing diagram
ad5751 rev. a | page 9 of 32 absolute maximum ratings t a = 25c, unless otherwise noted. transient currents of up to 100 ma do not cause scr latch-up. table 4. stresses above those listed under absolute maximum ratings may cause permanent damage to the device. this is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. parameter rating avdd to gnd ?0.3 v to +58 v dvcc to gnd ?0.3 v to +7 v digital inputs to gnd ?0.3 v to dv cc + 0.3 v, or 7 v (whichever is less) digital outputs to gnd ?0.3 v to dv cc + 0.3 v, or 7 v (whichever is less) vref to gnd ?0.3 v to +7 v vsense+ to gnd ?0.3 v to av dd vin to gnd ?0.3 v to +7 v vout, iout to gnd ?0.3 v to av dd operating temperature range industrial ?40c to +105c storage temperature range ?65c to +150c junction temperature (t j max) 125c 32-lead lfcsp package ja thermal impedance 28c/w lead temperature jedec industry standard soldering j-std-020 esd caution
ad5751 rev. a | page 10 of 32 pin configuration and fu nction descriptions pin 1 indicator top view (not to scale) ad5751 1 sdo/vfault 2 clrsel 3 clear 4 dvcc 5 gnd 6 sync/rset 7 s clk/outen 8 sdin/r0 24 vsense+ 23 vout 22 gnd 21 gnd 20 comp1 19 comp2 18 iout 17 avdd 9 a d 2 / r 1 1 0 a d 1 / r 2 1 1 a d 0 / r 3 1 2 r e x t 2 1 3 r e x t 1 1 4 v r e f 1 5 v i n 1 6 g n d 3 2 n c / i f a u l t 3 1 f a u l t / t e m p 3 0 r e s e t 2 9 h w s e l e c t 2 8 n c 2 7 n c 2 6 n c 2 5 n c notes 1. nc = no connect. 2 . the exposed paddle is tied to gnd. 07269-005 figure 4. pin configuration table 5. pin function descriptions pin no. mnemonic description 1 sdo/vfault serial data output (sdo). in software mode, this pin is used to cloc k data from the input shift register in readback mode. data is clocked out on the rising edge of sclk and is valid on the falling edge of sclk. this pin is a cmos output. short-circuit fault alert (vfault). in hardware mode, th is pin acts as a short-circuit fault alert pin and is asserted low when a short-circuit error is detected. this pin is an open-drain output and must be connected to a pull-up resistor. 2 clrsel in hardware or software mode, this pin selects the clear value, either zero-scale or midscale code. in software mode, this pin is implemented as a logic or with the internal clrsel bit. 3 clear active high input. asserting this pin sets the output current/voltage to zero-scale code or midscale code of range selected (user-selectable). clear is a logic or with the internal clear bit. see the asynchronous clear (clear) section for more details. in software mode, during power-up, the clear pi n level determines the pow er-on condition of the voltage channel, which can be active 0 v or tristate. 4 dvcc digital power supply. 5 gnd ground connection. 6 sync /rset positive edge-sensitive latch ( sync ). in software mode, a rising edge parallel loads the input shift register data into the ad5751, also updating the output. resistor select (rset). in hardware mode, this pin selects whether the internal or the external current sense resistor is used. if rset = 0, the external sense resistor is chosen. if rset = 1, the internal sense resistor is chosen. 7 sclk/outen serial clock input (sclk). in software mode, data is clocked into the input shift register on the falling edge of sclk. this pin operates at clock speeds up to 50 mhz. output enable (outen). in hardware mode , this pin acts as an output enable pin. 8 sdin/r0 serial data input (sdin). in software mode , data must be valid on the falling edge of sclk. range decode bit (r0). in hardware mode, this pin, in conjunction with r1, r2, and r3, selects the output current/voltage range setting on the part. 9 ad2/r1 device addressing bit (ad2). in software mode, this pin, in conjunction with ad0 and ad1, allows up to eight devices to be addressed on one bus. range decode bit (r1). in hardware mode, this pin, in conjunction with r0, r2, and r3, selects the output current/voltage range setting on the part.
ad5751 rev. a | page 11 of 32 pin no. mnemonic description 10 ad1/r2 device addressing bit (ad1). in software mode, this pin, in conjunction with ad0 and ad2, allows up to eight devices to be addressed on one bus. range decode bit (r2). in hardware mode, this pin, in conjunction with r0, r1, and r3, selects the output current/voltage range setting on the part. 11 ad0/r3 device addressing bit (ad0). in software mode, this pin, in conjunction with ad1 and ad2, allows up to eight devices to be addressed on one bus. range decode bit (r3). in hardware mode, this pin, in conjunction with r0, r1, and r2, selects the output current/voltage range setting on the part. 12, 13 rext2, rext1 a 15 k external current setting resistor can be connected between the rext1 and rext2 pins to improve the iout temperature drift performance. 14 vref buffered reference input. 15 vin buffered analog input (0 v to 4.096 v). 16 gnd ground connection. 17 avdd positive analog supply. 18 iout current output. 19, 20 comp2, comp1 optional compensation capacitor connections for the voltage output buffer. these are used to drive higher capacitive loads on the output. these pins al so reduce overshoot on the output. care should be taken when choosing the value of the capacitor connected between the comp1 and comp2 pins because it has a direct influence on th e settling time of the output. see the driving large capacitive loads section for further details. 21 gnd ground connection. 22 gnd ground connection. 23 vout buffered analog output voltage. 24 vsense+ sense connection for the positive voltage output load connection. 25, 26, 27, 28 nc no connect. can be tied to gnd. 29 hw select this part is used to configure the part to hardware or software mode. hw select = 0 selects software control. hw select = 1 selects hardware control. 30 reset in software mode, this pin resets the part to its power-on state. active low. in hardware mode, there is no reset. if using the part in hardware mode, the reset pin should be tied high. 31 fault/temp fault alert (fault). in software mode, this pin acts as a general fault aler t pin. it is asserted low when an open-circuit, short-circuit, overtemperature error, or pec interface error is detected. this pin is an open- drain output and must be connected to a pull-up resistor. overtemperature fault (temp). in hardware mode, this pin acts as an overtemperature fault pin. it is asserted low when an overtemperature error is detect ed. this pin is an open-drain output and must be connected to a pull-up resistor. 32 nc/ifault no connect (nc). in software mode, this pin is a no connect. instead, tie this pin to gnd. open-circuit fault alert (ifault). in hardware mode, this pin acts as an open-circuit fault alert pin. it is asserted low when an open-circuit error is detect ed. this pin is an open-drain output and must be connected to a pull-up resistor. 33 (epad) exposed paddle the exposed paddle is tied to gnd.
ad5751 rev. a | page 12 of 32 typical performance characteristics 0.010 0.008 0.006 0.004 0.002 0 ?0.002 ?0.004 ?0.006 ?0.008 ?0.010 0.020 0.293 0.585 0.878 1.170 1.463 1.755 2.048 2.341 2.633 2.926 3.218 3.511 3.803 4.096 integral nonlinearity error (%fsr) 07269-014 0v to 5v 0v to 10v 0v to 40v v in (v) figure 5. integral nonlinearity error vs. v in 0.010 0.008 0.006 0.004 0.002 0 ?0.002 ?0.004 ?0.006 ?0.008 ?0.010 ?40 25 105 temperature (c) integral nonlinearity error (%fsr) 07269-015 0v to 5v range 0v to 10v range 0v to 40v range figure 6. integral nonlinearity error vs. temperature 0.008 0.006 0.004 0.002 0 ?0.002 ?0.004 ?0.006 ?0.008 ?0.010 0.010 0.020 0.293 0.585 0.878 1.170 1.463 1.755 2.048 2.341 2.633 2.926 3.218 3.511 3.803 4.096 total unadjusted error (%fsr) 07269-016 0v to 5v 0v to 10v 0v to 40v v in (v) figure 7. total unadjusted error vs. v in 0.10 0.08 0.06 0.04 0.02 0 ?0.02 ?0.04 ?0.06 ?0.08 ?0.10 ?40 25 105 temperature (c) 07269-017 positive/negative total unadjusted error (%fsr) 0v to 5v positive tue 0v to 10v positive tue 0v to 40v positive tue 0v to 5v negative tue 0vto10vnegativetue 0vto40vnegativetue figure 8. total unadjusted error vs. temperature 0.05 0.04 0.03 0.02 0.01 0 ?0.01 ?0.02 ?0.03 ?0.04 ?40 25 105 temperature (c) full-scale error (%fsr) 07269-018 0v to 5v range 0v to 10v range 0v to 40v range figure 9. full-scale error vs. temperature 0.03 0.04 0.02 0.01 0 ?0.01 ?0.02 ?0.03 ?0.04 ?40 25 105 temperature (c) gain error (%fsr) 07269-019 0v to 5v range 0v to 10v range 0v to 40v range figure 10. gain error vs. temperature
ad5751 rev. a | page 13 of 32 3.0 3.5 4.0 2.5 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?40 25 105 temperature (c) offset error (mv) 07269-020 0v to 5v range 0v to 10v range 0v to 40v range figure 11. offset error vs. temperature 0.008 0.010 0.006 0.004 0.002 0 ?0.002 ?0.004 ?0.006 ?0.008 ?0.010 24 48 55 supply voltage (v) integral nonlinearity error (%fsr) 07269-021 5v linearity, no load 10v linearity, no load 40v linearity, no load figure 12. inl error vs. supply voltage 0.010 0.008 0.006 0.004 0.002 0 ?0.002 ?0.010 ?0.004 ?0.006 ?0.008 24 48 55 supply voltage (v) total unadjusted error (%fsr) 07269-022 0v to 5v positive tue 0v to 10v positive tue 0v to 40v positive tue 0v to 5v negative tue 0v to 10v negative tue 0v to 40v negative tue figure 13. total unadjusted error vs. supply voltage 1.00 0.95 0.90 0.85 0.80 0.75 0.70 ?40 25 105 temperature (c) headroom (v) 07269-023 v dd headroom, load off figure 14. avdd headroom, 0 v to 10 v range, output set to 10 v, load off 0.007 0.006 0.005 0.004 0.003 0.002 0.001 ?0.001 ?0.002 0 ?15 ?13 ?11 ?9 ?7 ?5 ?3 ?1 1 3 5 7 9 11 13 15 source/sink current (ma) output voltage delta (v) 07269-024 5v range figure 15. source and sink capability of output amplifier 12 10 8 6 4 2 0 27221712 72 ?3 ?8 voltage (v) time (s) 07269-025 figure 16. full-scale posi tive step, 10 v range
ad5751 rev. a | page 14 of 32 5v/div 1s/div 07269-029 12 10 8 6 4 2 0 27221712 72 ?3 ?8 voltage (v) time (s) 07269-026 figure 17. full-scale negative step, 10 v range figure 20. peak-to-peak noise (0.1 hz to 10 hz bandwidth) 40 35 30 25 20 15 10 5 0 ?5 2.5 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 v out (mv) time (ms) 07269-027 100v/div 1s/div 07269-030 figure 18. v out vs. time on power-up, load = 2 k || 200 pf figure 21. peak-to-peak noise (100 khz bandwidth) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 1.0 0.8 0.6 0.4 0.2 0 ?0.2 2.0 1.5 v dd v out 1.0 0.5 0 ?0.5 ?1.0 ?1.5 v dd (v) v out (v) time (ms) 07269-031 ch1 5.00v ch2 20.0mv b w m1.0s a ch1 3.00v 1 2 07269-028 figure 22. v dd and v out vs. time on power-up figure 19. v out enable glitch, load = 2 k || 1 nf
ad5751 rev. a | page 15 of 32 current output 0.004 0.003 0.002 0.001 0 ?0.001 ?0.002 ?0.003 ?0.004 ?0.005 0.005 0.020 0.293 0.585 0.878 1.170 1.463 1.755 2.048 2.341 2.633 2.926 3.218 3.511 3.803 4.096 integral nonlinearity (%fsr) 07269-032 v in (v) 4ma to 20ma external r set resistor 0ma to 20ma external r set resistor 0ma to 24ma external r set resistor figure 23. integral nonlinearity error vs. v in , external r set resistor 0.004 0.003 0.002 0.001 0 ?0.001 ?0.002 ?0.003 ?0.004 ?0.005 0.005 0.020 0.293 0.585 0.878 1.170 1.463 1.755 2.048 2.341 2.633 2.926 3.218 3.511 3.803 4.096 integral nonlinearity (%fsr) 07269-033 4ma to 20ma internal r set resistor 0ma to 20ma internal r set resistor 0ma to 24ma internal r set resistor v in (v) figure 24. integral nonlinearity error vs. v in , internal r set resistor 0.010 0.008 0.006 0.004 0.002 0 ?0.002 ?0.004 ?0.006 ?0.008 ?0.010 24v 48v 55v supply voltage (avdd) integral nonlinearity (%fsr) 07269-034 4ma to 20ma external r set linearity 0ma to 20ma external r set linearity 0ma to 24ma external r set linearity figure 25. integral nonlinearity current mode, external r set sense resistor 0.010 0.008 0.006 0.004 0.002 0 ?0.002 ?0.004 ?0.006 ?0.008 ?0.010 24v 48v 55v supply voltage (avdd) integral nonlinearity (%fsr) 07269-035 4ma to 20ma internal r set linearity 0ma to 20ma internal r set linearity 0ma to 24ma internal r set linearity figure 26. integral nonlinearity current mode, internal r set sense resistor 0.04 0.03 0.02 0.01 0 ?0.01 ?0.02 ?0.03 ?0.04 ?0.05 0.05 0.020 0.293 0.585 0.878 1.170 1.463 1.755 2.048 2.341 2.633 2.926 3.218 3.511 3.803 4.096 total unadjusted error (%fsr) 07269-036 4ma to 20ma external r set tue 0ma to 20ma external r set tue 0ma to 24ma external r set tue v in (v) figure 27. total unadjusted error vs. v in , external r set resistor 0.04 0.03 0.02 0.01 0 ?0.01 ?0.02 ?0.03 ?0.04 ?0.05 0.05 0.020 0.293 0.585 0.878 1.170 1.463 1.755 2.048 2.341 2.633 2.926 3.218 3.511 3.803 4.096 total unadjusted error (%fsr) 07269-037 v in (v) 4ma to 20ma internal r set tue 0ma to 20ma internal r set tue 0ma to 24ma internal r set tue figure 28. total unadjusted error vs. v in , internal r set resistor
ad5751 rev. a | page 16 of 32 0.020 0.015 0.010 0.005 0 ?0.005 ?0.010 ?0.015 ?0.020 24v 48v 55v supply voltage (avdd) total unadjusted error (%fsr) 07269-038 4ma to 20ma external r set positive tue 0ma to 20ma external r set positive tue 0ma to 24ma external r set positive tue 4ma to 20ma external r set negative tue 0ma to 20ma external r set negative tue 0ma to 24ma external r set negative tue figure 29. total unadjusted error current mode, external r set sense resistor 0.010 0.005 0 ?0.005 ?0.010 ?0.015 ?0.020 ?0.025 24v 48v 55v supply voltage (avdd) total unadjusted error (%fsr) 07269-039 4ma to 20ma internal r set negative tue 0ma to 20ma internal r set negative tue 0ma to 24ma internal r set negative tue 4ma to 20ma internal r set positive tue 0ma to 20ma internal r set positive tue 0ma to 24ma internal r set positive tue figure 30. total unadjusted error current mode, internal r set sense resistor 0.003 0.004 0.005 0.002 0.001 0 ?0.001 ?0.002 ?0.003 ?0.004 ?0.005 ?40 25 105 temperature (c) integral nonlinearity (%fsr) 07269-040 4ma to 20ma internal r set linearity 0ma to 20ma internal r set linearity 0ma to 24ma internal r set linearity figure 31. integral nonlinearity error vs. temperature, internal r set sense resistor 0.003 0.004 0.005 0.002 0.001 0 ?0.001 ?0.002 ?0.003 ?0.004 ?0.005 ?40 25 105 temperature (c) integral nonlinearity (%fsr) 07269-041 4ma to 20ma external r set linearity 0ma to 20ma external r set linearity 0ma to 24ma external r set linearity figure 32. integral nonlinearity error vs. temperature, external r set sense resistor 0.06 0.08 0.10 0.04 0.02 0 ?0.02 ?0.04 ?0.06 ?0.08 ?0.10 ?40 25 105 temperature (c) positive/negative tue (%fsr) 07269-042 4ma to 20ma internal r set positive tue 0ma to 20ma internal r set positive tue 0ma to 24ma internal r set positive tue 4ma to 20ma internal r set negative tue 0ma to 20ma internal r set negative tue 0ma to 24ma internal r set negative tue figure 33. total unadjusted error vs. temperature, internal r set sense resistor 0.06 0.08 0.10 0.04 0.02 0 ?0.02 ?0.04 ?0.06 ?0.08 ?0.10 ?40 25 105 temperature (c) positive/negative tue (%fsr) 07269-043 4ma to 20ma external r set positive tue 0ma to 20ma external r set positive tue 0ma to 24ma external r set positive tue 4ma to 20ma external r set negative tue 0ma to 20ma external r set negative tue 0ma to 24ma external r set negative tue figure 34. total unadjusted erro r vs. temperature, external r set sense resistor
ad5751 rev. a | page 17 of 32 40 45 50 35 30 25 20 15 10 5 0 ?40 25 105 temperature (c) zero-scale error (a) 07269-044 4ma to 20ma external r set 0ma to 20ma external r set 0ma to 24ma external r set figure 35. zero-scale error vs. temperature, external r set sense resistor 40 35 30 25 20 15 10 5 0 ?40 25 105 temperature (c) zero-scale error (a) 07269-045 4ma to 20ma internal r set 0ma to 20ma internal r set 0ma to 24ma internal r set figure 36. zero-scale error vs. temperature, internal r set sense resistor 3 2 1 0 ?1 ?2 ?3 ?40 25 105 temperature (c) offset error (a) 07269-046 4ma to 20ma internal r set 0ma to 20ma internal r set 0ma to 24ma internal r set figure 37. offset error vs. temperature, internal r set sense resistor 3 4 2 1 0 ?1 ?2 ?3 ?40 25 105 temperature (c) offset error (a) 07269-047 4ma to 20ma external r set 0ma to 20ma external r set 0ma to 24ma external r set figure 38. offset error vs. temperature, external r set sense resistor 0.03 0.04 0.05 0.02 0.01 0 ?0.01 ?0.02 ?0.03 ?0.04 ?0.05 ?40 25 105 temperature (c) full-scale error (%fsr) 07269-048 4ma to 20ma external r set 0ma to 20ma external r set 0ma to 24ma external r set figure 39. full-scale error vs. temperature, external r set sense resistor 0.06 0.08 0.10 0.04 0.02 0 ?0.02 ?0.04 ?0.06 ?0.08 ?0.10 ?40 25 105 temperature (c) full-scale error (%fsr) 07269-049 4ma to 20ma internal r set 0ma to 20ma internal r set 0ma to 24ma internal r set figure 40. full-scale error vs. temperature, internal r set sense resistor
ad5751 rev. a | page 18 of 32 0.06 0.08 0.10 0.04 0.02 0 ?0.02 ?0.04 ?0.06 ?0.08 ?0.10 ?40 25 105 temperature (c) gain error (%fsr) 07269-050 4ma to 20ma external r set 0ma to 20ma external r set 0ma to 24ma external r set figure 41. gain error vs. temperature, external r set sense resistor 0.06 0.08 0.10 0.04 0.02 0 ?0.02 ?0.04 ?0.06 ?0.08 ?0.10 ?40 25 105 temperature (c) gain error (%fsr) 07269-051 4ma to 20ma internal r set 0ma to 20ma internal r set 0ma to 24ma internal r set figure 42. gain error vs. temperature, internal r set sense resistor 2.00 2.05 2.10 1.95 1.90 1.85 1.80 1.75 1.70 1.65 ?40 25 105 temperature (c) compliance (v) 07269-052 av dd compliance voltage figure 43. output comp liance vs. temperature tested when i out = 10.8 ma, 0 ma to 24 ma range selected 12 10 8 6 4 2 0 ?2 0.000010 ?0.000010 ?0.000008 ?0.000006 ?0.000004 ?0.000002 0 0.000002 0.000004 0.000006 0.000008 10 v dd i out ?10 ?8 ?6 ?4 ?2 0 2 4 6 8 v dd (v) i out (a) time (ms) 07269-053 figure 44. output current vs. time on v dd power-up 0 ?18 ?16 ?14 ?12 ?10 ?8 ?6 ?4 ?2 8 ?2?101234567 time (s) 07269-054 i out ( a) figure 45. output current vs. time on output enable, 0 ma to 20 ma range 0.025 0.020 0.015 0.010 0.005 0 68 615448 41 3428 21 14 81 ?12 ?6 current (a) time (s) 07269-055 figure 46. 4 ma to 20 ma output current step
ad5751 rev. a | page 19 of 32 3000 2500 2000 1500 1000 500 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 di cc (a) logic level (v) dv cc = 5v dv cc = 3v 07269-056 figure 47. di cc vs. logic input voltage 4.10 4.05 4.00 3.95 3.90 3.85 3.80 3.75 24 48 55 av dd (v) ai dd (ma) 07269-057 figure 48. ai dd vs. av dd , v out = 0 v 4.10 4.05 4.00 3.95 3.90 3.85 3.80 3.75 24 48 55 07269-058 ai dd (ma) av dd (v) figure 49. ai dd vs. av dd , i out = 0 ma
ad5751 rev. a | page 20 of 32 terminology tot a l un a dju s te d e r ror ( t u e ) tue is a measure of the output error taking all the various errors into account: inl error, offset error, gain error, and output drift over supplies, temperature, and time. tue is expressed as a percentage of full-scale range (% fsr). relative accuracy or integral nonlinearity (inl) inl is a measure of the maximum deviation, in % fsr, from a straight line passing through the endpoints of the output driver transfer function. a typical inl vs. input voltage plot is shown in figure 5 . full-scale error full-scale error is the deviation of the actual full-scale analog output from the ideal full-scale output. full-scale error is expressed as a percentage of full-scale range (% fsr). full-scale tc full-scale tc is a measure of the change in the full-scale error with a change in temperature. it is expressed in ppm fsr/c. gain error gain error is a measure of the span error of the output. it is the deviation in slope of the output transfer characteristic from the ideal expressed in % fsr. a plot of gain error vs. temperature is shown in figure 10 . gain error tc gain error tc is a measure of the change in gain error with changes in temperature. gain error tc is expressed in ppm fsr/c. zero-scale error zero-scale error is the deviation of the actual zero-scale analog output from the ideal zero-scale output. zero-scale error is expressed in millivolts (mv). zero-scale tc zero-scale tc is a measure of the change in zero-scale error with a change in temperature. zero-scale error tc is expressed in ppm fsr/c. offset error offset error is a measurement of the difference between the actual vout and the ideal vout expressed in millivolts (mv) in the linear region of the transfer function. it can be negative or positive. output voltage settling time output voltage settling time is the amount of time it takes for the output to settle to a specified level for a half-scale input change. slew rate the slew rate of a device is a limitation in the rate of change of the output voltage. the output slewing speed is usually limited by the slew rate of the amplifier used at its output. slew rate is measured from 10% to 90% of the output signal and is expressed in v/s. current loop voltage compliance current loop voltage compliance is the maximum voltage at the iout pin for which the output current is equal to the programmed value. power-on glitch energy power-on glitch energy is the impulse injected into the analog output when the ad5751 is powered on. it is specified as the area of the glitch in nv-sec. power supply rejection ratio (psrr) psrr indicates how the output is affected by changes in the power supply voltage.
ad5751 rev. a | page 21 of 32 theory of operation the ad5751 is a single-channel, low cost, precision, voltage/ current output driver with hardware or software programmable output ranges. the software ranges are configured via an spi-/ microwire-compatible serial interface. the hardware ranges are programmed using the range pins (r0 to r3). the analog input to the ad5751 is provided from a low voltage, single-supply dac (0 v to 4.096 v), which is internally conditioned to provide the desired output current/voltage range. the output current range is programmable across three ranges: 0 ma to 20 ma, 0 ma to 24 ma, or 4 ma to 20 ma. the voltage output is provided from a separate pin that can be configured to provide 0 v to 5 v, 0 v to 10 v, and 0 v to 40 v output ranges. an overrange of 20% is available on the 5 v and 10 v output voltage ranges, and of 10% on the 0 v to 40 v range. the vout and iout pins can be connected together. an overrange of 2% is available on the 0 ma to 20 ma, 0 ma to 24 ma, and 4 ma to 20 ma current ranges. the current and voltage outputs are available on separate pins. only one output can be enabled at one time. the output range is selected by programming the r3 to r0 bits in the control register (see table 7 and table 8 ). figure 50 and figure 51 show a typical configuration of ad5751 in software mode and in hardware mode, respectively, in an output module system. the hw select pin chooses whether the part is configured in software or hardware mode. the analog input to the ad5751 is provided from a low voltage, single-supply dac such as the ad506x or ad566x, which can provide an output range of 0 v to 4.096 v. the supply and reference for the dac, as well as the reference for the ad5751, can be supplied from a reference such as the adr392 . the ad5751 can operate with a single supply up to 55 v. software mode in current mode, software-selectable output ranges include 0 ma to 20 ma, 0 ma to 24 ma, or 4 ma to 20 ma. in voltage mode, software-selectable output ranges include 0 v to 5 v, 0 v to 10 v, 0 v to 40 v. 07269-006 vsense+ vin sclk vdd refin sdi/din sdo sync1 sync sdo sdin sclk ad506x ad566x mcu vout 0v to 5v, 0v to 10v, 0v to 40v iout 0ma to 20ma, 0ma to 24ma, 4ma to 20ma vout range scale iout range scale vout short fault iout open fault overtemp fault status register serial interface vref hw select fault adp1720 adr392 a vdd a gnd avdd gnd ad5751 figure 50. typical system configuration in software mode (pull-up resistors not shown for open-drain outputs)
ad5751 rev. a | page 22 of 32 07269-007 vsense+ r3 r2 r1 output range select pins vin sclk vdd refin sdi/din sdo sync1 ad506x ad566x mcu vout 0v to 5v, 0v to 10v, 0v to 40v iout 0ma to 20ma, 0ma to 24ma, 4ma to 20ma vout range scale iout range scale vref r0 temp vfault ifault adp1720 adr392 ad5751 a vdd a gnd outen hw select dvcc avdd gnd figure 51. typical system configuration in hardware mode using internal dac reference (pull-up resistors not shown for open-dra in outputs) table 6. suggested parts for use with the ad5751 dac reference power resolution/accuracy description ad5660 internal adp1720 1 16-bit/12-bit mid end system, single channel, internal reference ad5664r internal n/a 16-bit/12-bit mid end system, quad channel, internal reference ad5668 internal n/a 16-bit/12-bit mid end system, octal channel, internal reference ad5060 adr434 adp1720 16-bit/16-bit high end system, single channel, external reference ad5064 / ad5066 adr434 n/a 16-bit/16-bit high end system, qu ad channel, external reference ad5662 adr392 2 adr392 2 16-bit/12-bit mid end system, single channel, external reference ad5664 adr392 2 n/a 16-bit/12-bit mid end system, quad channel, external reference 1 adp1720 input range up to 28 v. 2 adr392 input range up to 15 v.
ad5751 rev. a | page 23 of 32 currrent output architecture the voltage input from the analog input vin core (0 v to 4.096 v) is either converted to a current (see figure 52 ), which is then mirrored to the supply rail so that the application simply sees a current source output with respect to an internal reference voltage, or it is buffered and scaled to output a software-selectable unipolar voltage range (see figure 53 ). the reference is used to provide internal offsets for range and gain scaling. the selecta- ble output range is programmable through the digital interface (software mode) or via the range pins (r0 to r3) (hardware mode). 07269-008 a v dd vin vref a1 a2 r1 r3 r2 t1 t2 range decode from interface vout range scaling iout figure 52. current output configuration 0 7269-009 vin (0v to 4.096v) vref vout short fault vout vsense+ gnd range decode from interface vout range scaling figure 53. voltage output driving inductive loads when driving inductive or poorly defined loads, connect a 0.01 f capacitor between iout and gnd. this ensures stability with loads beyond 50 mh. there is no maximum capacitance limit. the capacitive component of the load may cause slower settling. voltage output amplifier the voltage output amplifier is capable of driving a load of 1 k (for 0 v to 5 v and 0 v to 10 v ranges) and a load of 5 k (for 0 v to 40 v range) and capacitive loads up to 2 f (with an external compensation capacitor on the comp1 and comp2 pins). the source and sink capabilities of the output amplifier can be seen in figure 15 . the slew rate is 2 v/s. internal to the device, there is a 2.5 m resistor connected between vout and vsense+. if a fault condition occurs, these resistors act to protect the ad5751 by ensuring that the amplifier loop is closed so that the part does not enter into an open-loop condition. the current and voltage are output on separate pins and cannot be output simultaneously. this allows the user to tie both the current and voltage output pins together and configure the end system as a single-channel output. driving large capacitive loads the voltage output amplifier is capable of driving capacitive loads of up to 1 f with the addition of a nonpolarized compensation capacitor between the comp1 and comp2 pins. without the compensation capacitor, up to 20 nf capacitive loads can be driven. care should be taken to choose an appropriate value for the c comp capacitor. this capacitor, while allowing the ad5751 to drive higher capacitive loads and reduce overshoot, increases the settling time of the part and therefore affects the bandwidth of the system. considered values of this capacitor should be in the range of 0 nf to 4 nf depending on the trade-off required between settling time, overshoot, and bandwidth. power-on state of the ad5751 on power-up, the ad5751 senses whether hardware or software mode is loaded and sets the power-up conditions accordingly. in software spi mode, the power-up state of the output is dependent on the state of the clear pin. if the clear pin is pulled high, the part powers up, driving an active 0 v on the output. if the clear pin is pulled low, the part powers up with the voltage output channel in tristate mode. in both cases, the current output channel powers up in the tristate condition (0 ma). this allows the voltage and current outputs to be connected together if desired. to put the part into normal operation, the user must set the outen bit in the control register to enable the output and, in the same write, set the output range configuration using the r3 to r0 range bits. if the clear pin is still high (active) during this write, the part automatically clears to its normal clear state as defined by the programmed range and by the clrsel pin or the clrsel bit (see the asynchronous clear (clear) section for more details). the clear pin must be taken low to operate the part in normal mode. the clear pin is typically driven directly from a microcontroller. in cases where the power supply for the ad5751 supply is independent of the microcontroller power supply, the user can connect a weak pull-up resistor to dvcc or a pull-down resistor to ground to ensure that the correct power-up condition is achieved independent of the microcontroller. a 10 k pull-up/ pull-down resistor on the clear pin should be sufficient for most applications. if hardware mode is selected, the part powers up to the conditions defined by the r3 to r0 range bits and the status of the outen or clear pin. it is recommended to keep the output disabled when powering up the part in hardware mode.
ad5751 rev. a | page 24 of 32 default registers at power-on the ad5751 power-on-reset circuit ensures that all registers are loaded with zero code. in software spi mode, the part powers up with all outputs disabled (outen bit = 0). the user must set the outen bit in the control register to enable the output and, in the same write, set the output range configuration using the r3 to r0 bits. if hardware mode is selected, the part powers up to the conditions defined by the r3 to r0 bits and the status of the outen pin. it is recommended to keep the output disabled when powering up the part in hardware mode. reset function in software mode, the part can be reset using the reset pin (active low) or the reset bit (reset = 1). a reset disables both the current and voltage outputs to their power-on condition. the user must write to the outen bit to enable the output and, in the same write, set the output range configuration. the reset pin is a level sensitive input; the part stays in reset mode as long as the reset pin is low. the reset bit clears to 0 following a reset command to the control register. in hardware mode, there is no reset. if using the part in hardware mode, the reset pin should be tied high. outen in software mode, the output can be enabled or disabled using the outen bit in the control register. when the output is disabled, both the current and voltage channels go into tristate. the user must set the outen bit to enable the output and simultaneously set the output range configuration. in hardware mode, the output can be enabled or disabled using the outen pin. when the output is disabled, both the current and voltage channels go into tristate. the user must write to the outen pin to enable the output. it is recommended that the output be disabled when changing the ranges. software control software control is enabled by connecting the hw select pin to ground. in software mode, the ad5751 is controlled over a versatile 3-wire serial interface that operates at clock rates up to 50 mhz. it is compatible with spi, qspi?, microwire, and dsp standards. input shift register the input shift register is 16 bits wide. data is loaded into the device msb first as a 16-bit word under the control of a serial clock input, sclk. data is clocked in on the falling edge of sclk. the input shift register consists of 16 control bits, as shown in table 7 . the timing diagram for this write operation is shown in figure 2 . the first three bits of the input shift register are used to set the hardware address of the ad5751 device on the printed circuit board (pcb). up to eight devices can be addressed per board. bit d11, bit d1, and bit d0 must always be set to 0 during any write sequence. table 7. input shift register contents for a write operationcontrol register msb lsb d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 a2 a1 a0 r/ w 0 r3 r2 r1 r0 clrsel outen clear rset reset 0 0 table 8. input shift register descriptions for control register bit description a2, a1, a0 used in association with the ad2, ad1, and ad0 external pins to determine which part is being addressed by the system controller. a2 a1 a0 function 0 0 0 addresses part with pin ad2 = 0, pin ad1 = 0, pin ad0 = 0. 0 0 1 addresses part with pin ad2 = 0, pin ad1 = 0, pin ad0 = 1. 0 1 0 addresses part with pin ad2 = 0, pin ad1 = 1, pin ad0 = 0. 0 1 1 addresses part with pin ad2 = 0, pin ad1 = 1, pin ad0 = 1. 1 0 0 addresses part with pin ad2 = 1, pin ad1 = 0, pin ad0 = 0. 1 0 1 addresses part with pin ad2 = 1, pin ad1 = 0, pin ad0 = 1. 1 1 0 addresses part with pin ad2 = 1, pin ad1 = 1, pin ad0 = 0. 1 1 1 addresses part with pin ad2 = 1, pin ad1 = 1, pin ad0 = 1. r/ w indicates a read from or a write to the addressed register.
ad5751 rev. a | page 25 of 32 bit description r3, r2, r1, r0 selects the output configuration in conjunction with rset. rset r3 r2 r1 r0 output configuration 0 0 0 0 0 4 ma to 20 ma (external 15 k current sense resistor). 0 0 0 0 1 0 ma to 20 ma (external 15 k current sense resistor). 0 0 0 1 0 0 ma to 24 ma (external 15 k current sense resistor). 0 0 0 1 1 unused command. do not program. 0 0 1 0 0 unused command. do not program. 0 0 1 0 1 0 v to 5 v. 0 0 1 1 0 0 v to 10 v. 0 0 1 1 1 unused command. do not program. 0 1 0 0 0 unused command. do not program. 0 1 0 0 1 0 v to 6.0 v (20% overrange). 0 1 0 1 0 0 v to 12.0 v (20% overrange). 0 1 0 1 1 unused command. do not program. 0 1 1 0 0 unused command. do not program. 0 1 1 0 1 unused command. do not program. 0 1 1 1 0 0 v to 40 v. 0 1 1 1 1 0 v to 44 v. 1 0 0 0 0 4 ma to 20 ma (internal current sense resistor). 1 0 0 0 1 0 ma to 20 ma (internal current sense resistor). 1 0 0 1 0 0 ma to 24 ma (internal current sense resistor). 1 0 0 1 1 unused command. do not program. 1 0 1 0 0 unused command. do not program. 1 0 1 0 1 0 v to 5 v. 1 0 1 1 0 0 v to 10 v. 1 0 1 1 1 unused command. do not program. 1 1 0 0 0 unused command. do not program. 1 1 0 0 1 0 v to 6.0 v (20% overrange). 1 1 0 1 0 0 v to 12.0 v (20% overrange). 1 1 0 1 1 unused command. do not program. 1 1 1 0 0 unused command. do not program. 1 1 1 0 1 3.92 ma to 20.4 ma (internal current sense resistor). 1 1 1 1 0 0 ma to 20.4 ma (internal current sense resistor). 1 1 1 1 1 0 ma to 24.5 ma (internal current sense resistor). clrsel sets clear mode to zero scale or midscale. see the asynchronous clear (clear) section. clrsel function 0 clear to 0 v. 1 clear to midscale in unipolar mode; clear to zero scale in bipolar mode. outen output enable bit. this bit must be set to 1 to enable the outputs. clear software clear bit; active high. rset select internal/external current sense resistor. rset function 1 select internal current sense resistor; used with r3 to r0 bits to select range. 0 select external current sense resistor; used with r3 to r0 bits to select range. reset resets the part to its power-on state.
ad5751 rev. a | page 26 of 32 readback operation readback mode is activated by selecting the correct device address (a2, a1, a0) and then setting the r/ w bit to 1. by default, the sdo pin is disabled. after having addressed the ad5751 for a read operation, setting r/ w to 1 enables the sdo pin and sdo data is clocked out on the 5 th rising edge of sclk. after the data has been clocked out on sdo, a rising edge on sync disables (tristate) the sdo pin again. status register data (see ) and control register data are both available during the same read cycle. table 9 the status bits comprise four read-only bits. they are used to notify the user of specific fault conditions that occur, such as an open circuit or short circuit on the output, overtemperature error, or an interface error. if any of these fault conditions occur, a hardware fault is also asserted low, which can be used as a hardware interrupt to the controller. see the detailed description of features section for a full explanation of fault conditions. hardware control hardware control is enabled by connecting the hw select pin to dvcc. in this mode, the r3, r2, r1, and r0 pins, in conjunction with the rset pin, are used to configure the output range, as per table 8 . in hardware mode, there is no status register. the fault condi- tions (open circuit, short circuit, and overtemperature) are available on pin ifault, pin vfault, and pin temp. if any one of these fault conditions is set, a low is asserted on the specific fault pin. ifault, vfault, and temp are open-drain outputs and, therefore, can be connected together to allow the user to generate one interrupt to the system controller to communicate a fault. if hardwired in this way, it is not possible to isolate which fault occurred in the system. transfer function the ad5751 consists of an internal signal conditioning block that maps the analog input voltage to a programmed output range. the available analog input range is 0 v to 4.096 v. for all ranges, both current and voltage, the ad5751 imple- ments a straight linear mapping function, where 0 v maps to the lower end of the selected range and 4.096 v maps to the upper end of the selected range. table 9. input shift register contents for a read operationstatus register msb lsb d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 a2 a1 a0 1 0 r3 r2 r1 r0 clrsel outen rset pec error over temp iout fault vout fault table 10. status bit options bit description pec error this bit is set if there is an interface error detected by crc-8 error checking. see the detailed description of features section. over temp this bit is set if the ad5751 co re temperature exceeds approximately 150c. iout fault this bit is set if there is an open circuit on the iout pin. vout fault this bit is set if there is a short circuit on the vout pin.
ad5751 rev. a | page 27 of 32 detailed description of features o utput fault alertsoftware mode i n software mode, the ad5751 is equipped with one fault pin; this is an open-drain output allowing several ad5751 devices to be connected together to one pull-up resistor for global fault detection. in software mode, the fault pin is forced active low by any one of the following fault scenarios: ? the voltage at iout attempts to rise above the compliance range due to an open-loop circuit or insufficient power supply voltage. the internal circuitry that develops the fault output avoids using a comparator with window limits because this requires an actual output error before the fault output becomes active. instead, the signal is generated when the internal amplifier in the output stage has less than approximately 1 v of remaining drive capability. thus, the fault output activates slightly before the com- pliance limit is reached. because the comparison is made within the feedback loop of the output amplifier, the output accuracy is maintained by its open-loop gain, and an output error does not occur before the fault output becomes active. ? a short is detected on the voltage output pin (vout). the short-circuit current is limited to 15 ma. ? an interface error is detected due to the packet error checking failure (pec). see the packet error checking section. ? the core temperature of the ad5751 exceeds approximately 150c. o utput fault alerthardware mode i n hardware mode, the ad5751 is equipped with three fault pins: vfault, ifault, and temp. these are open-drain outputs allowing several ad5751 devices to be connected together to one pull-up resistor for global fault detection. in hardware control mode, these fault pins are forced active by any one of the following fault scenarios: ? an open-circuit is detected. the voltage at iout attempts to rise above the compliance range, due to an open-loop circuit or insufficient power supply voltage. the internal circuitry that develops the fault output avoids using a comparator with window limits because this requires an actual output error before the fault output becomes active. instead, the signal is generated when the internal amplifier in the output stage has less than approximately 1 v of remaining drive capability. thus, the fault output activates slightly before the compliance limit is reached. because the comparison is made within the feedback loop of the output amplifier, the output accuracy is maintained by its open- loop gain, and an output error does not occur before the fault output becomes active. if this fault is detected, the ifault pin is forced low. ? a short is detected on the voltage output pin. the short- circuit current is limited to 15 ma. if this fault is detected, the vfault pin is forced low. ? the core temperature of the ad5751 exceeds approx- imately 150c. if this fault is detected, the temp pin is forced low. voltage output short-circuit protection under normal operation the voltage output sinks and sources up to 12 ma and maintains specified operation. the maximum current that the voltage output delivers is 15 ma; this is the short-circuit current. asynchronous clear (clear) clear is an active high clear that allows the voltage output to be cleared to either zero-scale code or midscale code, and is user-selectable via the clrsel pin or the clrsel bit of the input shift register, as described in table 8 . (the clear select feature is a logical or function of the clrsel pin and the clrsel bit). the current loop output clears to the bottom of its programmed range. when the clear signal is returned low, the output returns to its programmed value or to a new programmed value. a clear operation can also be performed via the clear command in the control register. table 11. clrsel options output clear value clrsel unipolar output voltage range unipolar current output range 0 0 v zero-scale; for example: 4 ma on the 4 ma to 20 ma range 0 ma on the 0 ma to 20 ma 1 midscale midscale; for example: 12 ma on the 4 ma to 20 ma range 10 ma on the 0 ma to 20 ma range external current setting resistor referring to figure 1 , r set is an internal sense resistor and is part of the voltage-to-current conversion circuitry. the nominal value of the internal current sense resistor is 15 k. to allow for overrange capability in current mode, the user can also select the internal current sense resistor to be 14.7 k, giving a nominal 2% overrange capability. this feature is available in the 0 ma to 20 ma, 0 ma to 24 ma, and 4 ma to 20 ma current ranges. the stability of the output current value over temperature is dependent on the stability of the value of r set . as a method of improving the stability of the output current over temperature, an external low drift resistor can be connected to the rext1 and rext2 pins of the ad5751, which can be used instead of the internal resistor. the external resistor is selected via the input shift register. if the external resistor option is not used, the rext1 and rext2 pins should be left floating.
ad5751 rev. a | page 28 of 32 programmable overrange modes the ad5751 contains an overrange mode for most of the available ranges. the overranges are selected by configuring the r3, r1, r1, and r0 bits (or pins) accordingly. in voltage mode, depending on selected range, the overranges are 10% or 20%, providing programmable output ranges of 0 v to 6 v, 0 v to 12 v, and 0 v to 44 v. the 0 v to 4.096 v analog input remains the same. in current mode, the overranges are typically 2%. in current mode, the overrange capability is only available on three ranges, 0 ma to 20 ma, 0 ma to 24 ma, and 4 ma to 20 ma. for these ranges, the analog input also remains the same (0 v to 4.096 v). packet error checking to verify that data has been received correctly in noisy environments, the ad5751 offers the option of error checking based on an 8-bit (crc-8) cyclic redundancy check. the device controlling the ad5751 should generate an 8-bit frame check sequence using the following polynomial: c ( x ) = x 8 + x 2 + x 1 + 1 this is added to the end of the data-word, and 24 data bits are sent to the ad5751 before taking sync high. if the ad5751 receives a 24-bit data frame, it performs the error check when sync goes high. if the check is valid, then the data is written to the selected register. if the error check fails, the fault pin goes low and bit d3 of the status register is set. after reading this register, this error flag is cleared automatically and the fault pin goes high again. sclk sdin sync update on sync high d15 (msb) d0 (lsb) 16-bit data 16-bit data transer?no error checking sclk sdin sync fault update after sync high only if error check passed fault goes low if error check fails d23 (msb) d8 (lsb) d7 d0 16-bit data 8-bit fcs 16-bit data transer with error checking 07269-010 figure 54. pec error checking timing
ad5751 rev. a | page 29 of 32 applications information transient voltage protection the ad5751 contains esd protection diodes that prevent damage from normal handling. the industrial control environment can, however, subject i/o circuits to much higher transients. to protect the ad5751 from excessively high voltage transients, external power diodes and a surge current limiting resistor may be required, as shown in figure 55 . the constraint on the resistor value is that during normal operation the output level at iout must remain within its voltage compliance limit of av dd ? 2.75 v and the two protection diodes and resistor must have appropriate power ratings. further protection can be added with transient voltage suppressors if needed. i out av dd av dd ad5751 r p r load 0 7269-011 figure 55. output transient voltage protection thermal considerations it is important to understand the effects of power dissipation on the package and how it affects junction temperature. the internal junction temperature should not exceed 125c. the ad5751 is packaged in a 32-lead, 5 mm 5 mm lfcsp pack- age. the thermal impedance, ja , is 28c/w. it is important that the devices not be operated under conditions that cause the junction temperature to exceed its limit. worst-case conditions occur when the ad5751 are operated from the maximum av dd (55 v) and driving the maximum current (24 ma) directly to ground. the quiescent current of the ad5751 should also be taken into account, nominally ~4 ma. the following calculations estimate maximum power dissipation under these worst-case conditions, and determine maximum ambient temperature based on this. these figures assume that proper layout and grounding techniques are followed to minimize power dissipation, as outlined in the layout guidelines section. table 12. thermal and supply considerations considerations 32-lead lfcsp package maximum allowed power dissipation when operating at an ambient temperature of 85c w42.1 28 85125 = ? = ? maximum allowed ambient temperature when operating from a supply of 55 v and driving 24 ma directly to ground (include 4 ma for internal ad5751 current) t jmax ? ( p d ja ) = 125 ? ((55 0.028) 28) = 81.8c maximum allowed supply voltage when operating at an ambient temperature of 85c and driving 24 ma directly to ground () v51 28028.0 85125 = ? = ?
ad5751 rev. a | page 30 of 32 layout guidelines in any circuit where accuracy is important, careful consideration of the power supply and ground return layout helps to ensure the rated performance. the pcb on which the ad5751 is mounted should be designed so that the ad5751 lies on the analog plane. the ad5751 should have ample supply bypassing of 10 f in parallel with 0.1 f on each supply, located as close to the package as possible, ideally right up against the device. the 10 f capacitors are the tantalum bead type. the 0.1 f capaci- tor should have low effective series resistance (esr) and low effective series inductance (esi) such as the common ceramic types, which provide a low impedance path to ground at high frequencies to handle transient currents due to internal logic switching. in systems where there are many devices on one board, it is often useful to provide some heat sinking capability to allow the power to dissipate easily. ad5751 gnd plane board 07269-012 figure 56. paddle connection to board the ad5751 has an exposed paddle beneath the device. connect this paddle to the gnd of the ad5751. for optimum performance, special considerations should be used to design the motherboard and to mount the package. for enhanced thermal, electrical, and board level performance, the exposed paddle on the bottom of the package should be soldered to the corresponding thermal land paddle on the pcb (gnd). thermal vias should be designed into the pcb land paddle area to further improve heat dissipation. galvanically isolated interface in many process control applications, it is necessary to provide an isolation barrier between the controller and the unit being controlled to protect and isolate the controlling circuitry from any hazardous common-mode voltages that may occur. the i coupler? family of products from analog devices, inc., provides voltage isolation in excess of 5.0 kv. the serial loading structure of the ad5751 makes it ideal for isolated interfaces because the number of interface lines is kept to a minimum. figure 57 shows a 4-channel isolated interface to the ad5751 using an adum1400. for further information, visit http://www.analog.com/icouplers . v ia v oa to sclk v ib v ob to sdin v ic v oc to sync v id v od to clear 1 additional pins omitted for clarity. encode decode encode decode encode decode encode decode 07269-013 adum1400 1 serial clock out serial data out sync out control out controller figure 57. isolated interface microprocessor interfacing microprocessor interfacing to the ad5751 is via a serial bus that uses a protocol compatible with microcontrollers and dsp proces- sors. the communication channel is a 3-wire (minimum) interface consisting of a clock signal, a data signal, and a sync signal. the ad5751 requires a 16-bit data-word with data valid on the falling edge of sclk.
ad5751 rev. a | page 31 of 32 compliant to jedec standards mo-220-vhhd-2 011708-a 0.23 0.18 outline dimensions 0.30 0.20 ref 0.80 max 0.65 typ 0.05 max 0.02 nom 12 max 1.00 0.85 0.80 seating plane coplanarity 0.08 1 32 8 9 25 24 16 17 0.50 0.40 0.30 3.50 ref 0.50 bsc pin 1 indi c ator top view 5.00 bsc sq 4.75 bsc sq 3.25 3.10 sq 2.95 pin 1 indicator 0.60 max 0.60 max 0.25 min exposed pad (bottom view) for proper connection of the exposed pad, refer to the pin configuration and function descriptions section of this data sheet. figure 58. 32-lead lead frame chip scale package [lfcsp_vq] 5 mm 5 mm body, very thin quad (cp-32-2) dimensions shown in millimeters ordering guide model 1 temperature range package description package option ad5751acpz ?40c to +105c 32-lead lfcsp_vq cp-32-2 AD5751ACPZ-REEL7 ?40c to +105c 32-lead lfcsp_vq cp-32-2 ad5751bcpz ?40c to +105c 32-lead lfcsp_vq cp-32-2 ad5751bcpz-reel7 ?40c to +105c 32-lead lfcsp_vq cp-32-2 1 z = rohs compliant part.
ad5751 rev. a | page 32 of 32 notes ?2009-2010 analog devices, inc. all rights reserved. trademarks and registered trademarks are the prop erty of their respective owners. d07269-0-5/10(a)

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