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general description the max16805/max16806 led drivers eliminate the need for microcontrollers or switch-mode converters. an eeprom-programmable led current-sense reference sim - plifies production by using one sense resistor to set the led current for all led bins. a dual-mode dim pin and an on- board 200hz ramp generator allow for pwm dimming with an analog or pwm control signal. the analog control signal at dimming input dim allows for the "theater dimming" effect to be implemented. fast turn-on/-off times ensure a wide-range pwm operation, while waveshaping circuitry minimizes emi. eeprom-programmable led current foldback makes it possible to operate at a high input voltage, while saving the cost and space associated with having a large heatsink. the max16806 works with an external thermal sensor to main - tain maximum led junction temperature by folding back the led current. the thermal foldback temperature knee and slope are eeprom programmable. the max16806 sw pin supplies necessary wetting current to a momentary switch. applications emergency vehicle warning lights navigation and marine indicators features eeprom or i 2 c dynamically programmable: ? led current foldback for high input voltage ? led current reference ? led current thermal foldback (max16806) on-board 200hz ramp generator eliminates the need for c pwm signal flexible analog or pwm control for pwm or theater dimming wetting current and debounce for momentary switch (max16806) 5.5v to 40v input with up to 39v output capability 35ma to 350ma adjustable led current waveshaping minimizes emi during dimming output short-circuit and overtemperature protection -40c to +125c operating temperature range pin configurations appear at end of data sheet. 19-0625; rev 2; 9/14 + denotes a lead(pb)-free/rohs-compliant package. * ep = exposed pad. part temp range pin- package max16805 atp+ -40c to +125c 20 tqfn-ep* max16806 atp+ -40c to +125c 20 tqfn-ep* max16805 in out v5 leds i led r sense 0.1f +5.5v to +40v +5v reg cs+ 0.1f cs- dim gnd en v5 analog control pwm dimming scl sda serial clock serial data i led max16806 max6613 ? in out v5 leds r sense 0.1f +5.5v to +40v pwm control dimming +5v reg cs+ 0.1f cs- dim pwm dimming gnd en tfp/scl tfn/sda v cc v5 gnd out sw ? max6613 thermal sensor is optional. max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback typical operating circuits ordering information evaluation kit available downloaded from: http:///
in to gnd .............................................................. -0.3v to +45v dim, out, en to gnd ............................... -0.3v to (v in + 0.3v) in slew rate (20v < v in < 45v) ................................. 250mv/s sda, scl (max16805), tfn/sda, tfp/scl (max16806) to gnd ............................ -0.3v to +6v cfd, cs+, v5 to gnd ............................................ -0.3v to +6v dgnd and cs- to gnd ....................................... -0.3v to +0.3v out short circuited to gnd duration (v in < +16v) .......... hour maximum current into any pin (except in and out) ...... 20ma continuous power dissipation (t a = +70c) 20-pin thin qfn (derate 34.5mw/c above +70c) ......................... 2758.6mw operating temperature range ......................... -40c to +125c junction temperature ...................................................... +150c storage temperature range ............................ -65c to +150c lead temperature (soldering, 10s) ................................. +300c (v in = v en = 12v, c v5 = 0.1f, i v5 = 0, cs- = gnd, r sense = 0.56, v dim = 4v, dgnd = gnd, tfp/scl = 5v, tfn/sda = 0v, sw = cfd = open, t a = t j = -40c to +125c, unless otherwise noted. typical values are at t a = +25c.) (note 1) parameter symbol conditions min typ max units supply voltage range v in (note 2) 5.5 40 v ground current i g i load = 350ma 2.5 4.5 ma shutdown supply current i shdn v en 0.3v 12 40 a guaranteed output current i out r sense = 0.55? 350 ma output current accuracy 35ma < i out < 350ma, r sense tolerance not included 3.0 % dropout voltage (note 3) v do i out = 350ma, 12v < v in < 40v 0.4 1.2 v i out = 350ma, 6.5v < v in < 12v 0.5 1.5 output current slew rate (external pwm signal at dim) current rising, dim rising to 4v 17 ma/s current falling, dim falling to 0.6v 17 short-circuit current v out = 0v 600 ma enable input en input current i en 100 na en input-voltage high v ih 2.8 v en input-voltage low v il 0.6 v enable turn-on time t on en rising edge to 90% of out 225 s 5v regulator output voltage regulation (max16806) v5 6.5v < v in < 40v 0 < i v5 < 0.5ma, sw = gnd 4.9 5.1 5.3 v 0 < i v5 < 2ma, sw = open 4.9 5.1 5.3 output voltage regulation (max16805) v5 0 < i v5 < 2ma, 6.5v < v in < 40v 4.9 5.1 5.3 v current senseregulated r sense voltage v rsns v sense = [v cs+ - v cs- ], binning adjustment register at factory default (0x0f) 192 198 204 mv input current (cs+) v cs+ = 210mv 12 a max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 2 absolute maximum ratings stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. electrical characteristics downloaded from: http:///
(v in = v en = 12v, c v5 = 0.1f, i v5 = 0, cs- = gnd, r sense = 0.56, v dim = 4v, dgnd = gnd, tfp/scl = 5v, tfn/sda = 0v, sw = cfd = open, t a = t j = -40c to +125c, unless otherwise noted. typical values are at t a = +25c.) (note 1) parameter symbol conditions min typ max units input current (cs-) v cs+ = 210mv -75 a minimum regulated v sense programming range v sense(min) 99.4 103 106.6 mv maximum regulated v sense programming range v sense(max) 192 198 204 regulated v sense default voltage v sense(def) binning adjustment register at factory default (0x0f) 198 mv external pwm dimming input dim input current 0.5 a turn-on time t on after dim rising to 4v (note 4) 28 52 s turn-off time t off after dim falling to 0.6v (note 4) 19 38 s thermal foldback (max16806 with max6613) maximum thermal foldback knee point programming range tf knee(max) 326 335 354 mv minimum thermal foldback knee point programming range tf knee(min) 1143 1174 1213 minimum thermal foldback temperature programming range tf (min) +60 c maximum thermal foldback temperature programming range tf (max) +135 thermal foldback default threshold temperature v th thermal foldback knee point register at factory default (0x00) +60 c thermal foldback default threshold voltage tf vth 1.174 v minimum thermal foldback slope tf sl(min) 3.88 4 4.12 v/v maximum thermal foldback slope tf sl(max) 15.52 16 16.48 v/v thermal foldback default slope thermal foldback slope gain register at factory default (0x03) 4 v/v tfp/scl (scl for max16805) voltage compliance range v tfp i 2 c interface active -0.3 v5 v remote thermal sensor active +0.3 v5 tfn/sda (sda for max16805) voltage compliance range v tfn -0.3 v5 v minimum thermal foldback clamp current reduction range tf c(min) +25 c t a +125 c 40 % max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 3 electrical characteristics (continued) downloaded from: http:///
(v in = v en = 12v, c v5 = 0.1f, i v5 = 0, cs- = gnd, r sense = 0.56, v dim = 4v, dgnd = gnd, tfp/scl = 5v, tfn/sda = 0v, sw = cfd = open, t a = t j = -40c to +125c, unless otherwise noted. typical values are at t a = +25c.) (note 1) parameter symbol conditions min typ max units maximum thermal foldback clamp current reduction range tf c(max) +25c t a +125c 100 % default thermal foldback clamp current reduction range tf def thermal foldback clamp register at factory default (0x07), +25c t a +125c 40 % thermal protection thermal shutdown temperature t j(shdn) +155 c thermal shutdown hysteresis +23 c led current foldbackminimum input led current foldback range v cfd(min) 11.4 v maximum input led current foldback range v cfd(max) 16.4 v led current foldback default level v cfd led current foldback threshold register at factory default (0x00) 16.4 v led current foldback voltage step size v in > 11v, cfd register bit 3 = 0 0.71 v/step v in > 11v, cfd register bit 3 = 1 0.355 internal ramp generator internal ramp frequency f ramp 176 200 224 hz external sync frequency range f dim 80 2000 hz external sync voltage low 0.4 v external sync voltage high 2.8 v output current duty cycle i dc v dim = 0v 0 % v dim > (v ramp + 0.4v) (max16806), v dim > +3.3v (max16805) 100 minimum ramp peak programming range v ramp(min) 1.49 1.55 1.60 v maximum ramp peak programming range v ramp(max) 2.77 2.88 3.00 v ramp peak default voltage ramp peak register at factory default (0x07) 2.88 v ramp offset voltage 210 mv momentary switch interface (sw) (max16806) sw pullup current i sw v sw = 0v 1 3 ma sw input-voltage high v ih i sw = 100a 4 v sw input-voltage low v il 0.4 v minimum pulse width 120 ms minimum debounce time 40 ms max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 4 electrical characteristics (continued) downloaded from: http:///
(v in = v en = 12v, c v5 = 0.1f, i v5 = 0, cs- = gnd, r sense = 0.56, v dim = 4v, dgnd = gnd, tfp/scl = 5v, tfn/sda = 0v, sw = cfd = open, t a = t j = -40c to +125c, unless otherwise noted. typical values are at t a = +25c.) (note 1) note 1: all devices 100% production tested at t j = +25c. limits over the operating temperature range are guaranteed by design. note 2: resistors were added from out to cs+ to aid with the power dissipation during testing. note 3: dropout is measured as follows: connect a resistor from out to cs+. connect r sense = 0.56 from cs+ to cs-. set v in = v out +3v (record v out as v out1 ). reduce v in until v out = 0.97 x v out1 (record as v in2 and v out2 ). v do = v in2 - v out2 . note 4: t on time includes the delay and the rise time needed for i out to reach 90% of its final value. t off time is the time needed for i out to drop below 10%. see the typical operating characteristics . t on and t off are tested with 13 from out to cs+. note 5: tpf/scl (scl for max16805) and tpn/sda (sda for the max16805) are i 2 c interface compatible only when the max16805/max16806 are the only parts on the bus for production programming. note 6: c b is the total bus capacitance. parameter symbol conditions min typ max units eepromv in voltage for eeprom programming 20 22 24 v eeprom data-retention time 10 years i 2 c digital inputs (tfp/scl, tfn/sda) (note 5) logic input-voltage high v ih 2.8 v logic input-voltage low v il 0.8 v input capacitance 5 pf sda output voltage low v ol i sink = 3ma 0.4 v i 2 c interface timing (figure 1) serial clock frequency f scl 400 khz bus free time between stop and start condition t buf 1.3 s start condition hold time t hd:sta 0.6 s clock low period t low 1.3 s clock high period t high 0.6 s repeat start condition setup time t su:sta 0.6 s data hold time t hd:dat a master device must provide a hold time of at least 300ns for the sda signal (referred to v il of the scl signal) in order to bridge the undeined region of scls falling edge 0 0.9 s data setup time t su:dat 100 ns receive scl/sda rise time t r 300 ns receive scl/sda fall time t f 250 ns stop condition setup time t su:sto 0.6 s pulse width of spike suppressed t sp 50 ns transmit sda fall time i sink 6ma, c b 400pf (note 6) 250 ns max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 5 electrical characteristics (continued) downloaded from: http:///
(v in = 12v, v en = v in , c v5 = 0.1f, i v5 = 0, cs- = gnd, r sense = 0.56, connect out to cs+, v dim = 4v, sw = v fd = open, v tfp/sc = 5v, v tfn/sd = gnd, dgnd = gnd. t a = +25c, unless otherwise noted.) (v cs+ - v cs- ) vs. output current max16805 toc02 output current (ma) (v cs+ - v cs- ) (v) 320 290 230 260 80 110 140 170 200 50 0.196 0.197 0.198 0.199 0.200 0.201 0.202 0.203 0.204 0.2050.195 20 350 v in = 12v output current vs. input voltage max16805 toc03 input voltage (v) output current (ma) 14 12 2 4 6 8 10 50 100 150 200 250 300 350 400 0 0 16 i out = 350ma i out = 100ma dropout voltage vs. temperature max16805 toc04 temperature (c) dropout voltage (v) 110 95 65 80 -10 5 20 35 50 -25 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0 -40 125 v in = 12v i load = 350ma +5v regulator output vs. temperature max16805 toc05 temperature (c) +5v regulator output (v) 110 95 80 65 50 35 20 5 -10 -25 5.05 5.10 5.15 5.205.00 -40 125 no load i load = 1ma i load = 2ma +5v regulator output vs. input voltage max16805 toc06 input voltage (v) +5v regulator output (v) 35 30 25 20 15 10 5.05 5.10 5.15 5.205.00 5 40 i load = 1ma no load i load = 2ma shutdown current vs. temperature max16805 toc07 temperature (c) shutdown current (a) 110 95 80 65 50 35 20 5 -10 -25 5 10 20 15 25 30 35 0 -40 125 v in = 40v v in = 20v v in = 12v v in = 6.5v output current vs. temperature max16805 toc01 temperature (c) output current (ma) 110 95 65 80 -10 5 20 35 50 -25 50 100 150 200 250 300 350 400 450 0 -40 125 i load = 350ma i load = 35ma i load = 200ma i load = 100ma (v cs+ - v cs- ) vs. i v5 max16805 toc08 i v5 (ma) (v cs+ - v cs- ) (v) 7 6 5 4 3 2 1 0.1985 0.1990 0.1995 0.2000 0.2005 0.20100.1980 0 8 v in = 12 200hz dimmed operation max16805 toc09 20s/div v dim 2v/div i load 200ma/div 0v 0a i load = 350ma v in = 12v dim pulsed at 200hz (1% duty cycle) max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback maxim integrated 6 www.maximintegrated.com typical operating characteristics downloaded from: http:///
(v in = 12v, v en = v in , c v5 = 0.1f, i v5 = 0, cs- = gnd, r sense = 0.56, connect out to cs+, v dim = 4v, sw = v fd = open, v tfp/sc = 5v, v tfn/sd = gnd, dgnd = gnd. t a = +25c, unless otherwise noted.) led current rise time (expanded) max16805 toc11 20s/div v dim 2v/div i led 200ma/div 0v 0a dim pulsed at 200hz output current duty cycle vs. analog dim voltage max16805 toc12 v dim (v) output current duty cycle (%) 3 2 1 20 40 60 80 100 120 0 0 4 v in = 12v ramp register = 0x07cfd = gnd tfp = 5v tfn = gnd output current duty cycle vs. input voltage max16805 toc13 input voltage (v) output current duty cycle (%) 18 16 14 12 10 8 6 4 2 20 40 60 80 100 120 0 0 20 bit3 = 1 bit3 = 0 led current threshold register = (0x07) output clamp vs. thermal foldback slope max16805 toc15 v tfn (v) output clamp (%) 1.4 1.2 0.8 1.0 0.4 0.6 0.2 5 10 15 20 25 30 35 40 45 0 0 1.6 thermal slope = 4v/v thermal slope = 4v/v thermal slope = 8v/v thermal slope = 12v/v thermal foldbackclamp level = 40% thermal knee = +60c output current duty cycle vs. input voltage max16805 toc14 input voltage (v) output current duty cycle (%) 25 20 15 10 5 20 40 60 80 100 120 0 0 30 bit3 = 1 bit3 = 0 led current threshold register = (0x00) output response to sw input max16805 toc16 40ms/div v sw 5v/div v sense 200mv/div debounce time debounce time led current fall time (expanded) max16805 toc10 20s/div v dim 2v/div i led 200ma/div 0v 0a dim pulsed at 200hz max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback maxim integrated 7 www.maximintegrated.com typical operating characteristics (continued) downloaded from: http:///
pin name function max16805 max16806 1, 20 1, 20 out current regulated output. connect pins 1 and 20. 2, 3 2, 3 in input supply. bypass in with a 0.1f (min) capacitor to gnd. connect pins 2 and 3. 4 4 cfd led current foldback dimming enable input. leave cfd unconnected to enable the current foldback dimming function. drive cfd low to disable the led current foldback dimming function. 5 5 dgnd digital ground. connect to gnd. 6 scl i 2 c serial clock input 7 sda i 2 c serial-data input/output 8, 10, 16 8, 10,16 gnd ground 9, 11, 18 9, 18 n.c. no connection. leave unconnected (internal connection). 12, 15 12, 15 v5 5v regulated output. connect a 0.1f capacitor from v5 to gnd. connect pin 12 to 15. 13 13 cs+ positive input of the internal differential ampliier. connect the current-sense resistor between cs+ and cs- to program the output current level. 14 14 cs- negative input of the internal differential ampliier. connect the current-sense resistor between cs- and cs+ to program the output current level. 17 17 dim dimming input. see the dimming input (dim) section. 19 19 en enable input. drive en high to enable the output and the 5v regulator. 11 sw momentary switch interface. see the momentary switch interface (sw) section. 6 tfp/scl thermal foldback positive input/i 2 c serial clock input. see the thermal sensor inputs/i 2 c interface (tfp/scl and tfn/sda) section. 7 tfn/sda thermal foldback negative input/i 2 c serial-data input/output. see the thermal sensor inputs/i 2 c interface (tfp/scl and tfn/sda) section. ep ep ep exposed pad. connect to the ground plane for improved power dissipation. do not use as a ground connection for the part. max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 8 pin description downloaded from: http:///
max16805max16806 en dim in cfd sw (n.c.) v5 v5 regulator 1.25v in v5 differential sense amplifier thermal shutdown eeprom and serial interface reference generator tfp/scl (scl) tfn/sda (sda) current foldback por thermal foldback* trimmed bandgap *not part of the max16805( ) max16805 200hz ramp generator 210mv eeprom mux and logic gnd i_ reg in out cs+cs- trimmed bandgap pulse detector max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 9 functional diagram downloaded from: http:///
detailed description the max16805/max16806 are constant-current regula - tors that provide up to 350ma of current to one or more strings of high-brightness leds, and have a wide 5.5v to 40v operating input voltage range. the devices feature the i 2 c interface that allows communication with the inter - nal dynamic registers and eeprom. dynamic registers control the max16805/max16806 functions and can be updated in real time through the i 2 c interface. see table 2 for register addresses. turning off the input voltage clears the dynamic register contents. to save settings, store them into the eeprom. the max16805/max16806 load the stored settings into the dynamic registers at power-up. in addition, during normal operation a write command to the eeprom content transfer register loads the stored settings into the dynamic register. information stored can be transferred into dynamic registers after issuing a write command to the eeprom content transfer register. the max16805/max16806s 5v regulator (v5) provides up to 2ma of current to external circuitry. however, the max16806s 5v regulator can deliver 2ma of output cur - rent only when the momentary switch is not used. when the momentary switch is active, the max16806 achieves up to 0.5ma of current. in addition, the max16805/ max16806 feature thermal and output shortcircuit protec - tion. the wide operating voltage range helps protect the device against large transients up to 45v such as those found in load dump situations. the max16805/max16806 use a feedback loop to con - trol the output current. the differential voltage across the sense resistor is compared to a fixed reference voltage and the error is amplified to serve as the drive to the internal pass device, see the functional diagram . the max16805/max16806 offer a programmable led cur - rent reference using the binning adjustment register. these devices are current controllers internally optimized for driving the impedance range expected from 1 to 10 (or more) high-brightness leds. dimming input (dim) the max16805/max16806s dimming input operates with either an analog or pwm control signal. if the pulse detector detects three edges of a pwm signal with a frequency range between 80hz to 2khz, the max16805/ max16806 synchronize to external pwm input signal and pulse-width-modulate the led current. if an analog con - trol signal is applied to dim, the max16805/max16806 compare the dc input to an internally generated 200hz ramp to pulse-width-modulate the led current. the maxi - mum peak value of the 200hz ramp can be programmed using the ramp peak register. this allows the led cur - rent to be adjusted through the i 2 c interface from 50% (typ) to 100% in real time when v dim is 1.54v. the output current duty cycle is adjustable from 0% to 100% (0.21v < v dim < 3.1v). use the following formula to calculate the output current duty cycle: duty cycle = (v dim - 0.21v) / v ramp figure 1. i 2 c serial interface timing diagram sda scl t hd:sta t low t high t r t f t hd:dat t su:dat repeated start t su:sta t hd:sta t su:sto t sp stop start p t buf max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 10 downloaded from: http:///
the dimming feature can be used for led brightness adjustment (see the typical operating circuits ) and the - ater dimming. if the external pwm signal is used, theater dimming can be achieved by varying the pwm duty cycle. figure 2 shows a simple circuit that implements theater dimming with a dc input signal. thermal sensor inputs/i 2 c interface (tfp/scl and tfn/sda) the max16806 features dual-function inputs, tfp/scl and tfn/sda. in programming mode, tfp/scl and tfn/ sda serve as the i 2 c serial communication interface. tfp/scl and tfn/sda also serve as inputs for analog signals generated by an external temperature sensor such as the max6613. when the thermal sensor is not used, connect tfp/scl and tfn/sda through 50k resistors to v5 and gnd, respectively. the max16805 does not offer dual-function inputs. scl and sda are used only to communicate with the max16805 through the i 2 c interface. momentary switch interface (sw) the max16806 offers a momentary switch (sw) that overrides the analog dimming signal by latching the out - put current to 100% duty cycle. the max16806 does not override external pwm signal at dim or dimming caused by thermal or led current foldback. to latch the output current into a 100% duty cycle, press sw once. to restore the initial duty cycle determined by the dc level at dim, press sw again. the max16806 provides a minimum of 1ma of wetting current to the momentary switch. overtemperature protection the max16805/max16806 enter a thermal shutdown in the event of overheating. this typically occurs in over - load or output short-circuit conditions. when the junction temperature exceeds t j = +155c (typ), the internal thermal protection circuitry turns off the pass device. the max16805/max16806 recover from thermal shutdown once the junction temperature drops by +23c (typ). this feature allows self-protection by thermally cycling in the event of a short-circuit or overload condition. digital interface the max16805/max16806 feature an i 2 c, 2-wire serial interface consisting of a bidirectional serial data line (sda) and a serial clock line (scl). sda and scl facili - tate bidirectional communication between the max16805/ max16806 and the master device at rates up to 400khz. the master (typically a microcontroller) initiates data transfer on the bus and generates scl. start and stop conditions both scl and sda remain high when the interface is not busy. a master controller signals the beginning of a trans - mission with a start condition by transitioning sda from high to low while scl is high. the master controller issues a stop condition by transitioning the sda from low to high while scl is high, when it finishes communicating with the slave. the bus is then free for another transmis - sion (figure 3). figure 2. theater dimming lightfigure 3. i 2 c communication start and stop conditions max16805max16806 in out v5 leds r sense v in theaterdimming signal +5v reg cs+ 0.1f cs- dim gnd en start condition s p sda scl stop condition max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 11 downloaded from: http:///
bit transfer one data bit is transferred during each clock pulse. the data on the sda line must remain stable while scl is high (figure 4). acknowledge the acknowledge bit is a clocked 9th bit that the recipient uses to handshake receipt each byte of data (figure 5). therefore, each byte effectively transferred requires 9 bits. the master controller generates the 9th clock pulse, and the recipient pulls down sda during the acknowledge clock pulse, so the sda line remains stable low during the high period of the clock pulse. slave address the max16805/max16806 have a 7-bit-long slave address (figure 6, table 1). the 8th bit following the 7- bit slave address is the r/ w bit. set the r/ w bit low for a write command and high for a read command. table 1. slave address figure 4. bit transfer figure 5. acknowledge figure 6. slave address write address (hex) read address (hex) 0xee 0xef data stable, data valid sda scl change of data allowed sda start scl 1 2 8 9 not acknowledge acknowledge sda start msb scl 1 2 3 4 5 6 7 8 a7 a6 a5 a4 a3 a2 a1 rw ack 9 max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 12 downloaded from: http:///
message format write to the max16805/max16806 by transmitting the devices slave address with r/ w , 8th bit set to zero fol - lowed by at least 1 byte of information (figure 7). the first byte of information is the command byte. the bytes received after the command byte are the data bytes. the first data byte goes into the internal register as selected by the command byte (figure 8). if there is more than one data byte, the max16805/max16806 auto-increment to the next register address locations to write the subse - quent data bytes. the max16805/max16806 auto-incre - ment up to the register address 0x05, eeprom content transfer register. a read operation is performed as follows: after the start condition (s), a 7-bit slave id is sent followed by an 8th bit (r/ w ) set to zero. a register address is then sent to specify the address location from which the read has to take place. to complete a read operation, the master needs to generate a repeat - ed start (sr) followed by the 7-bit slave id but with the 8th bit (r/ w ) set to 1 this time indicating a read operation. on the other hand, a read operation can be performed by sending in the 7-bit slave id followed by an 8th bit (r/ w ) set to 1 if the current address loca - tion happens to be the address location from which data needs to be read. table 2. registers address figure 8. command and a single data byte received figure 7. command byte received register name register address no. of bits/ register binning adjustment 0x00 4 ramp peak 0x01 3 led current foldback threshold (led_cft) 0x02 4 thermal foldback knee point 0x03 4 thermal foldback slope gain 0x04 2 thermal foldback clamp level 0x05 3 eeprom content transfer 0x06 eeprom program enable 0x08 password register 0xff acknowledge from max16805/max16806 acknowledge from max16805/max16806 acknowledge from max16805/max16806 rw command byte 1 byte data byte slave address a a 0 s a p acknowledge from max16805/max16806 acknowledge from max16805/max16806 0 s a a p rw slave address command byte max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 13 downloaded from: http:///
binning adjustment register (0x00) the binning adjustment register is a 4-bit register that sets the differential regulation voltage reference between cs+ and cs-. only the first 4 bits of the data byte update the binning adjustment register. the remaining 4 bits are ignored. see table 3. the factorydefault register value is 198mv. ramp peak register (0x01), max16806 the ramp peak register is a 3-bit register that sets the maximum peak value of an internally 200hz generated ramp. the ramp signal can be programmed for a peak value of 1.55v to 2.88v. only the first 3 bits of the data byte update the ramp peak register. the remaining 5 bits are ignored (see table 4). the factory-default register value is 2.88v. led current foldback threshold (led_cft) register (0x02) led_cft is a 4-bit register that sets the threshold for the onset of the led current foldback operation. only the first 3 bits of the data byte program the led_cft register. bit 3, not shown in table 5, sets the led current foldback range. the max16805/max16806 start dimming the led current when the input voltage exceeds the led current foldback threshold. for bit 3 = 0, the dimming range is 1.2 times the programmed ramp peak voltage. for bit 3 = 1, the dimming range is 2.4 times the programmed ramp peak. to disable the led current foldback feature of the max16805/max16806 connect cft to gnd. the factory-default register value is 16v. table 3. binning adjustment table 4. ramp peak value table 5. led current foldback threshold regulation voltage (mv) bit 3 bit 2 bit 1 bit 0 hex 103.0 0 0 0 0 (0x00) 109.0 0 0 0 1 (0x01) 115.4 0 0 1 0 (0x02) 121.8 0 0 1 1 (0x03) 128.2 0 1 0 0 (0x04) 134.6 0 1 0 1 (0x05) 141.0 0 1 1 0 (0x06) 147.4 0 1 1 1 (0x07) 153.7 1 0 0 0 (0x08) 160.1 1 0 0 1 (0x09) 166.5 1 0 1 0 (0x0a) 173.0 1 0 1 1 (0x0b) 179.3 1 1 0 0 (0x0c) 185.7 1 1 0 1 (0x0d) 192.1 1 1 1 0 (0x0e) 198.0 1 1 1 1 (0x0f) ramp end point (v) bit 2 bit 1 bit 0 hex 1.55 0 0 0 (0x00) 1.74 0 0 1 (0x01) 1.93 0 1 0 (0x02) 2.12 0 1 1 (0x03) 2.32 1 0 0 (0x04) 2.51 1 0 1 (0x05) 2.70 1 1 0 (0x06) 2.88 1 1 1 (0x07) current foldback threshold (v) bit 2 bit 1 bit 0 hex 16.4 0 0 0 (0x00) 15.7 0 0 1 (0x01) 15.0 0 1 0 (0x02) 14.3 0 1 1 (0x03) 13.5 1 0 0 (0x04) 12.8 1 0 1 (0x05) 12.1 1 1 0 (0x06) 11.4 1 1 1 (0x07) max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 14 downloaded from: http:///
thermal foldback knee point (tfk) register (0x03), max16806 the tfk register is a 4-bit register that sets the thermal knee. only the first 4 bits of the data byte program the tfk register. the remaining 4 bits are ignored (see table 6). the max16806 initiates dimming once the differential volt - age between tfp/scl and tfn/sda drops below the pro - grammed thermal foldback knee. the factory-default reg - ister value is 1.174v, which corresponds to the max6613 thermal sensor output to +60c. thermal foldback slope gain register (0x04), max16806 thermal foldback slope gain register is a 2-bit register that sets the gain after the thermal foldback knee. only the first 2 bits of the data byte program the thermal foldback slope gain register. the remaining 6 bits are ignored (see table 7). the factory-default register value is 4v/v. table 6. thermal foldback knee table 7. thermal foldback slope gain thermal foldback knee point (c) (max6613) thermal foldback knee point (mv) bit 3 bit 2 bit 1 bit 0 hex 60 1174 0 0 0 0 (0x00) 65 1118 0 0 0 1 (0x01) 70 1062 0 0 1 0 (0x02) 75 1006 0 0 1 1 (0x03) 80 950 0 1 0 0 (0x04) 85 894 0 1 0 1 (0x05) 90 838 0 1 1 0 (0x06) 96 782 0 1 1 1 (0x07) 101 726 1 0 0 0 (0x08) 106 670 1 0 0 1 (0x09) 111 615 1 0 1 0 (0x0a) 116 559 1 0 1 1 (0x0b) 121 503 1 1 0 0 (0x0c) 126 447 1 1 0 1 (0x0d) 131 391 1 1 1 0 (0x0e) 136 335 1 1 1 1 (0x0f) thermal foldback slope gain (v/v) bit 1 bit 0 hex 16 0 0 (0x00) 12 0 1 (0x01) 8 1 0 (0x02) 4 1 1 (0x03) max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 15 downloaded from: http:///
thermal foldback clamp level register (0x05), max16806 thermal foldback clamp level is a 3-bit register that sets the minimum percentage of the led current. only the first 3 bits of the data byte program the thermal foldback clamp level register. the remaining 5 bits are ignored. see table 8. the factory-default register value is 40%. eeprom content transfer register (0x06) the max16805/max16806 use the eeprom content transfer register to transfer data from the eeprom to the dynamic registers. a write command issued to this register transfers data from the eeprom to the dynamic registers. data bytes written to the eeprom content transfer register do not have any significance. at power- up, the eeprom content is automatically loaded into the dynamic registers. eeprom program enable register (0x08) the eeprom program enable register enables the eeprom for programming. write to the eeprom programming enable register to initiate the eeprom pro - gramming cycle. data written to the register does not have any significance, however, it must be issued following a write command [(0xff), (0xca)] to the password register. applications information programming the led current the max16805/max16806 use a sense resistor across cs+ and cs- to set the led current. the differential sense amplifier connected across r sense provides ground-loop immunity and low-frequency noise rejection. the led current is given by the equation below: i led = v sense / r sense v sense is programmable from 103mv to 198mv using i 2 c. programming eeprom set v in to 22v before initiating the eeprom program - ming. the max16805/max16806 use dynamic registers to program the eeprom. once the desired dynamic registers have been updated with a setting, write the data byte (0xca) to the password register (0xff). the data byte (0xca) enables the eeprom programming mode. any other data byte except the (0xca) disables the eeprom programming mode. to transfer data from dynamic registers to the eeprom, write to eeprom program enable register (0x08). input voltage considerations for proper operation, the minimum input voltage must always be: v in(min) > v sense + v ft(max) + v do(max) where v ft(max) is the total forward voltage of all series connected leds and v do(max) is the maximum drop output voltage. table 8. thermal foldback clamp level thermal foldback clamp level (%) bit 2 bit 1 bit 0 hex 100 0 0 0 (0x00) 91 0 0 1 (0x01) 83 0 1 0 (0x02) 74 0 1 1 (0x03) 66 1 0 0 (0x04) 57 1 0 1 (0x05) 49 1 1 0 (0x06) 40 1 1 1 (0x07) max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 16 downloaded from: http:///
package type package code outline no. land pattern no. 20 tqfn-ep t2055mn+5 21-0140 90-0011 max16805 top view thin qfn thin qfn 1920 18 17 76 8 in cfd dgnd 9 out cs-v5 n.c. v5 1 + + 2 n.c. 4 5 15 14 12 11 en out n.c.gnd sda scl in cs+ 3 13 dim 16 10 gnd gnd max16806 1920 18 17 76 8 in cfd dgnd 9 out cs-v5 sw v5 1 2 n.c. 4 5 15 14 12 11 en out n.c.gnd tfn/sda tfp/scl in cs+ 3 13 dim 16 10 gnd gnd max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback www.maximintegrated.com maxim integrated 17 pin conigurationschip information process: bicmos-dmos package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. downloaded from: http:///
revision number revision date description pages changed 2 9/14 removed automotive references from the general description, applications, and detailed description sections 1, 10 revision history maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and speciications without n otice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. max16805/max16806 eeprom-programmable, high-voltage, 350ma led drivers with led current foldback ? 2014 maxim integrated products, inc. 18 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com. downloaded from: http:///

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