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w wm8215 60msps 10-bit 3-channel ccd digitiser wolfson microelectronics plc to receive regular email updates, sign up at http://www.wolfsonmicro.com/ enews production data, september 2012, rev 4.3 copyright ? 2012 wolfson microelectronics plc. description the wm8215 is a 10-bit analogue front end/digitiser ic which processes and digitises the analogue output signals from ccd sensors or contact image sensors (cis) at pixel sample rates of up to 60msps. the device includes thr ee analogue signal processing channels each of which contai ns reset level clamping, correlated double sampling and programmable gain and offset adjust functions. the output from each of these channels is time multiplexed into a single high-speed 10-bit analogue to digital converter. the digital output data is available in 10-bit wide parallel format. an internal 4-bit dac is suppli ed for internal reference level generation. this may be used to reference cis signals, in non-cds mode or to clamp ccd signals during reset level clamping. an external reference level may also be supplied. adc references are generated internally, ensuring optimum performance from the device. using an analogue supply voltage of 3.3v and a digital interface supply of 3.3v, the wm8215 typically only consumes 400mw. features ? 10-bit adc ? 60msps conversion rate ? low power ? 400mw typical ? 3.3v single supply operation ? 3 channel operation ? correlated double sampling ? programmable gain (9-bit resolution) ? programmable offset adjust (8-bit resolution) ? flexible clamp timing ? programmable clamp voltage ? internally generated voltage references ? 32-lead qfn package ? serial control interface applications ? digital copiers ? usb2.0 compatible scanners ? multi-function peripherals ? high-speed ccd/cis sensor interface block diagram
wm8215 production data w pd, rev 4.3, september 2012 2 table of contents descript ion ....................................................................................................... 1 ? featur es ............................................................................................................ 1 ? applications ..................................................................................................... 1 ? block diag ram ................................................................................................ 1 ? table of co ntents ......................................................................................... 2 ? pin config uration .......................................................................................... 3 ? ordering info rmation .................................................................................. 3 ? pin descri ption ................................................................................................ 4 ? absolute maximu m ratings ........................................................................ 5 ? recommended operatin g condit ions ..................................................... 5 ? thermal perfo rmance ................................................................................. 5 ? electrical charact eristics ..................................................................... 6 ? input video sampling .............................................................................................. 8 ? serial interface ..................................................................................................... 10 ? internal power on reset ci rcuit .......................................................... 11 ? device des cription ...................................................................................... 13 ? introduction ........................................................................................................... 13 ? input sampling ........................................................................................................ 13 ? reset level clamping (rlc) ................................................................................ 14 ? cds/non-cds processing..................................................................................... 16 ? offset adjust and programmable gain ........................................................ 16 ? adc input black level adjust ........................................................................... 17 ? overall signal flow summary ......................................................................... 18 ? calculating the output co de for a given input ...................................... 19 ? references .............................................................................................................. 20 ? power management .............................................................................................. 20 ? line-by-line operation ......................................................................................... 20 ? control interface ................................................................................................ 20 ? normal operat ing modes ................................................................................... 22 ? device conf iguration ................................................................................. 23 ? register map ............................................................................................................ 23 ? register map d escription .................................................................................. 24 ? applications in formation ........................................................................ 28 ? recommended external components ........................................................... 28 ? recommended external co mponent values .............................................. 28 ? package dime nsions .................................................................................... 29 ? important no tice ......................................................................................... 30 ? address: .................................................................................................................... 3 0 ? revision hi story ........................................................................................... 31 ? wm8215 production data w pd, rev 4.3, september 2012 3 pin configuration ordering information device temperature range package moisture sensitivity level peak soldering temperature wm8215csefl 0 to 70 o c 32-lead qfn (5x5x0.9mm) (pb-free) msl1 260 ? c wm8215csefl/r 0 to 70 o c 32-lead qfn (5x5x0.9mm) (pb-free, tape and reel) msl1 260 ? c note: reel quantity = 3,500 wm8215 production data w pd, rev 4.3, september 2012 4 pin description pin name type description 1 rsmp digital input reset sample pulse (when cds=1) or clamp control 2 mclk digital input master (adc) clock. this clock determines the adc conversion rate. 3 dgnd supply digital ground. 4 sen digital input enables the serial interface when high. 5 dvdd2 supply digital supply, all digital i/o pins. 6 sdi digital input serial data input. 7 sck digital input serial clock. 8 nc no connect no internal connection. 9 nc no connect no internal connection. digital output data bus. adc output data ( d9:d0) is available in 10-bit parallel format. 10 op[0] digital output d0 (lsb) 11 op[1] digital output d1 12 op[2] digital output d2 13 op[3] digital output d3 14 op[4] digital output d4 15 op[5] digital output d5 16 op[6] digital output d6 17 op[7] digital output d7 18 op[8] digital output d8 19 op[9]/sdo digital output d9 (msb) alternatively, pin op[9]/sdo may be us ed to output register read-back data when oeb=0, opd(register bit)=0 and sen has been pulsed high. see serial interface description in device descripti on section for further details. 20 avdd supply analogue supply. this must be operated at the same potential as dvdd1. 21 agnd1 supply analogue ground. 22 vrb analogue output lower reference voltage. this pin must be connected to agnd via a decoupling capacitor. 23 vrt analogue output upper reference voltage. this pin must be connected to agnd via a decoupling capacitor. 24 vrx analogue output input return bias voltage. this pin must be connected to agnd via a decoupling capacitor. 25 vrlc/vbias analogue i/o selectable analogue output voltage for rl c or single-ended bias reference. this pin would typically be connect ed to agnd via a decoupling capacitor. vrlc can be externally dr iven if programmed hi-z. 26 binp analogue input blue channel input video. 27 ginp analogue input green channel input video. 28 rinp analogue input red channel input video. 29 agnd2 supply analogue ground. 30 dvdd1 supply digital supply for logic and clock generator . this must be operated at the same potential as avdd. 31 oeb digital input output hi-z control. all digital output s set to high-impedance state when input pin oeb=1 or register bit opd=1. 32 vsmp digital input video sample pulse. wm8215 production data w pd, rev 4.3, september 2012 5 absolute maximum ratings absolute maximum ratings are stress ratings only. permanent damage to the device may be caused by continuously operating at or beyond these limits. device functional operating limits and guaranteed performance specificati ons are given under electrical characteristics at the te st conditions specified. esd sensitive device. this device is manufactured on a cmos process. it is therefore generically susceptible to damage from excessive static voltages. proper esd precautions must be taken during handling and storage of this device. wolfson tests its package types according to ipc/jedec j-std- 020b for moisture sensitivity to determine acceptable storage conditions prior to surface mount assembly. these levels are: msl1 = unlimited floor life at <30 ? c / 85% relative humidity. not normally stored in moisture barrier bag. msl2 = out of bag storage for 1 year at <30 ? c / 60% relative humidity. supplied in moisture barrier bag. msl3 = out of bag storage for 168 hours at <30 ? c / 60% relative humidity. supplied in moisture barrier bag. the moisture sensitivity level for each package type is specif ied in ordering information. condition min max analogue supply voltage: avdd gnd - 0.3v gnd + 4.2v digital supply voltages: dvdd1 ? 2 gnd - 0.3v gnd + 4.2v digital ground: dgnd gnd - 0.3v gnd + 0.3v analogue grounds: agnd1 ? 2 gnd - 0.3v gnd + 0.3v digital inputs, digital outputs and digital i/o pins gnd - 0.3v dvdd2 + 0.3v analogue inputs (rinp, ginp, binp) gnd - 0.3v avdd + 0.3v other pins gnd - 0.3v avdd + 0.3v operating temperature range: t a 0 ? c +70 ? c storage temperature after soldering -65 ? c +150 ? c notes: 1. gnd denotes the voltage of any ground pin. 2. agnd1, agnd2 and dgnd pins are intended to be operat ed at the same potential. differential voltages between these pins will degrade performance. recommended operating conditions condition symbol min typ max units operating temperature range t a 0 70 ? c analogue supply voltage avdd 2.97 3.3 3.63 v digital core supply voltage dvdd1 2.97 3.3 3.63 v digital i/o supply voltage dvdd2 2.97 3.3 3.63 v notes: 1. dvdd2 should be operated at the same potential as dvdd1 0.3v. thermal performance parameter symbol test conditions min typ max unit performance thermal resistance ? junction to case r jc t ambient = 25c 10.27 c/w thermal resistance ? junction to ambient r ja 29.45 c/w notes: 1. figures given are for package mounted on 4-layer fr4 according to jesd51-5 and jesd51-7. wm8215 production data w pd, rev 4.3, september 2012 6 electrical characteristics test conditions avdd = dvdd1 = dvdd2 = 3.3v, agnd = dgnd = 0v, t a = 25 ? c, mclk = 60mhz unless otherwise stated. parameter symbol test conditions min typ max unit overall system specification (including 10-bit adc, pga, offset and cds functions) conversion rate 60 msps full-scale input voltage range (see note 1) lowrefs=0, max gain lowrefs=0, min gain 0.25 3.03 vp-p vp-p lowrefs=1, max gain lowrefs=1, min gain 0.15 1.82 vp-p vp-p input signal limits (see note 2) v in agnd-0.3 avdd+0.3 v input capacitance 10 pf input switching impedance 45 ? full-scale transition error gain = 0db; pga[8:0] = 14(hex) 20 mv zero-scale transition error gain = 0db; pga[8:0] = 14(hex) 20 mv differential non-linearity dnl 0.75 lsb integral non-linearity inl 2 lsb channel to channel gain matching 1% % output noise min gain max gain 0.2 2.15 lsb rms lsb rms references upper reference voltage vrt lowrefs=0 lowrefs=1 1.95 2.05 1.85 2.25 v v lower reference voltage vrb lowrefs=0 lowrefs=1 0.95 1.05 1.25 1.25 v v input return bias voltage vrx 1.25 v diff. reference voltage (vrt-vrb) v rtb lowrefs=0 lowrefs=1 0.95 0.57 1.0 0.6 1.10 0.68 v v output resistance vrt, vrb, vrx 1 ?? vrlc/reset-level clamp (rlc) rlc switching impedance 45 ?? vrlc short-circuit current 2 ma vrlc output resistance 3 ? vrlc hi-z leakage current vrlc = 0 to avdd 1 ? a rlcdac resolution 4 bits rlcdac step size, rlcdacrng = 0 v rlcstep 0.173 v/step rlcdac step size, rlcdacrng = 1 v rlcstep lowrefs = 0 0.11 v/step lowrefs = 1 0.10 rlcdac output voltage at code 0(hex), rlcdacrng = 0 v rlcbot 0.4 v rlcdac output voltage at code 0(hex), rlcdacrng = 1 v rlcbot lowrefs = 0 0.4 v lowrefs = 1 rlcdac output voltage at code f(hex) rlcdacrng, = 0 v rlctop 3.0 v rlcdac output voltage at code f(hex), rlcdacrng = 1 v rlctop lowrefs = 0 2.05 1.85 v lowrefs = 1 rlcdac dnl -0.5 +0.5 lsb rlcdac inl +/-0.5 lsb notes: 1. full-scale input voltage denotes the peak input signal amplitude that can be gained to match the adc full-scale input range. wm8215 production data w pd, rev 4.3, september 2012 7 2. input signal limits are the limits within which the fu ll-scale input voltage signal must lie. test conditions avdd = dvdd1 = dvdd2 = 3.3v, agnd = dgnd = 0v, t a = 25 ? c, mclk = 60mhz unless otherwise stated. parameter symbol test conditions min typ max unit offset dac, monotonicity guaranteed resolution 8 bits differential non-linearity dnl 0.15 lsb integral non-linearity inl 0.4 lsb step size 2.00 mv/step output voltage code 00(hex) code ff(hex) -255 +255 mv mv programmable gain amplifier resolution 9 bits gain ] : [ pga * . . 0 8 511 34 7 66 0 ? v/v max gain, each channel g max 8 v/v min gain, each channel g min 0.66 v/v gain error, each channel 3 % analogue to digital converter resolution 10 bits speed 60 msps full-scale input range (2*(vrt-vrb)) lowrefs=0 1.9 2 2.2 v lowrefs=1 1.2 v digital specifications digital inputs high level input voltage v ih 0.7 ? dvdd2 v low level input voltage v il 0.2 ? dvdd2 v high level input current i ih 1 ? a low level input current i il 1 ? a input capacitance c i 5 pf digital outputs high level output voltage v oh i oh = 1ma dvdd2 - 0.5 v low level output voltage v ol i ol = 1ma 0.5 v high impedance output current i oz 1 ? a digital io pins applied high level input voltage v ih 0.7 ? dvdd2 v applied low level input voltage v il 0.2 ? dvdd2 v high level output voltage v oh i oh = 1ma dvdd2 - 0.5 v low level output voltage v ol i ol = 1ma 0.5 v low level input current i il 1 ? a high level input current i ih 1 ? a input capacitance c i 5 pf high impedance output current i oz 1 ? a supply currents ? total supply current ? active 116 ma ? analogue supply current ? active (three channel mode) 105 ma digital supply current ? active (three channel mode) 11 ma supply current ? full power down mode 20 ? a wm8215 production data w pd, rev 4.3, september 2012 8 input video sampling figure 1 three-channel cds input video timing (cds=1) figure 2 two-channel cds operation (cds=1) wm8215 production data w pd, rev 4.3, september 2012 9 figure 3 one-channel cds operation (cds=1) notes: 1. the relationship between input video signal and sample points is controlled by vsmp and rsmp. 2. when vsmp is high the input video signal is connected to the video sampling capacitors. 3. when rsmp is high the input video signal is connected to the reset sampling capacitors. 4. rsmp must not go high before the first falling edge of mclk after vsmp goes low. 5. it is required that the falling edge of vsm p should occur before the rising edge of mclk. 6. in 1-channel cds mode it is not possible to have an equally spaced video and reset sample points with a 45mhz mclk. 7. non-cds operation is also possible; rsmp is not required in this mode but can be used to control input clamping. timing constraints between vsmp and mclk remain unchanged for non-cds operation. test conditions avdd = dvdd1 = dvdd2 = 3.3v, agnd = dgnd = 0v, t a = 25 ? c, mclk = 60mhz for 3 and 2-channel mode and 45mhz for 1-channel mode unless otherwise stated. parameter symbol test conditions min typ max units mclk period ? 2/3 channel mode 1 channel mode t per 16.6 22.2 ns mclk high period ? 2/3 channel mode 1 channel mode t mclkh 6.7 8.3 11.1 ns mclk low period ? 2/3 channel mode 1 channel mode t mclkl 6.7 8.3 11.1 ns rsmp pulse high time t rsd 5 ns vsmp pulse high time t vsd 5 ns rsmp falling to vsmp rising time t rsfvsr 0 ns mclk rising to vsmp rising time t mrvsr 3 ns mclk falling to vsmp falling time t mfvsf 0 ns mclk falling to vsmp falling time in 1 channel mode t mfvsf 7 ns vsmp falling to mclk rising time t vsfmr 0 ns 1 st mclk falling edge after vsmp falling to rsmp rising time t mf1rs 1 ns 3-channel mode pixel period t pr3 50 ns 2-channel mode pixel period t pr2 33.3 ns wm8215 production data w pd, rev 4.3, september 2012 10 parameter symbol test conditions min typ max units 1-channel mode pixel period t pr1 22.2 ns output propagation delay t pd 5 10 ns output latency. from 1 st rising edge of mclk after vsmp falling to data output lat 7 mclk periods notes: 1. parameters are measured at 50% of the rising/falling edge. 2. in 1-channel mode, if t mfvsf is less than 9.5ns, the output amplitude of the wm8215 will decrease. serial interface figure 4 serial interface timing test conditions avdd = dvdd1 = dvdd2 = 3.3v, agnd = dgnd = 0v, t a = 25 ? c, mclk = 45mhz unless otherwise stated. parameter symbol test conditions min typ max units sck period t sper 83.3 ns sck high t sckh 37.5 ns sck low t sckl 37.5 ns sdi set-up time t ssu 6 ns sdi hold time t sh 6 ns sck rising to sen rising t scrser 37.5 ns sck falling to sen falling t scfsef 12 ns sen to sck set-up time t sec 12 ns sen pulse width t sew 60 ns sen low to sdo = register data t serd 30 ns sck low to sdo = register data t scrd 30 ns sck low to sdo = adc data t scrdz 30 ns note: 1. parameters are measured at 50% of the rising/falling edge wm8215 production data w pd, rev 4.3, september 2012 11 internal power on reset circuit figure 5 internal power on reset circuit schematic the wm8215 includes an internal power-on-reset circ uit, as shown in figure 5, which is used to reset the digital logic into a default state after power up. the por circuit is powered from avdd and monitors dvdd1. it asserts porb low if avdd or dvdd1 is below a minimum threshold. the power supplies can be brought up in any order but is important that either avdd is brought up and is stable before dvdd comes up or vice ve rsa as shown in figure 6 and figure 7. figure 6 typical power up sequence where avdd is powered before dvdd1 figure 6 shows a typical power-up sequence w here avdd comes up first. when avdd goes above the minimum threshold, vpora, there is enough volt age for the circuit to guarantee porb is asserted low and the chip is held in reset. in this condition, all writes to the control interface are ignored. now avdd is at full supply level. next dvdd1 ri ses to vpord_on and porb is released high and all registers are in their default state and writes to the control interface may take place. on power down, where avdd falls first, porb is asserted low whenever avdd drops below the minimum threshold vpora_off. wm8215 production data w pd, rev 4.3, september 2012 12 figure 7 typical power up sequence where dvdd1 is powered before avdd figure 7 shows a typical power-up sequence where dv dd1 comes up first. first it is assumed that dvdd1 is already up to specified operating volt age. when avdd goes above t he minimum threshold, vpora, there is enough voltage for the circuit to guar antee porb is asserted low and the chip is held in reset. in this condition, all writes to the control interface are ignored. when avdd rises to vpora_on, porb is released high and all registers are in their default state and writes to the control interface may take place. on power down, where dvdd1 falls first, porb is asserted low whenever dvdd1 drops below the minimum threshold vpord_off. symbol typ unit v pora 0.6 v v pora_on 1.2 v v pora_off 0.6 v v pord_on 0.7 v v pord_off 0.6 v table 1 typical por operation (typical values, not tested) note: it is recommended that every time power is cycl ed to the wm8215 a software reset is written to the software register to ensure that the contents of the control registers are at their default values before carrying out any other register writes. wm8215 production data w pd, rev 4.3, september 2012 13 device description introduction a block diagram of the device showing the si gnal path is presented on the front page of this datasheet. the wm8215 samples up to three inputs (rinp, ginp and binp) simultaneously. the device then processes the sampled video signal with respect to the video reset level or an internally/externally generated reference level using betw een one and three processing channels. each processing channel consists of an input sa mpling block with optional reset level clamping (rlc) and correlated double sampling (cds), an 8-bit programmable offset dac and a 9-bit programmable gain amplifier (pga). the processing channel outputs are switched alternat ely by a 3:1 multiplexer to the adc input. the adc then converts each result ing analogue signal to a 10-bit digita l word. the digital output from the adc is presented in parallel on the 10-bit wide output bus, op[9:0]. the ten output pins can be set to a high impedance state using either the oeb control pin or the opd register bit. on-chip control registers determi ne the configuration of the devic e, including the offsets and gains applied to each channel. these registers are programmable via a serial interface. input sampling the wm8215 can sample and process up to three inputs through one to three processing channels as follows: colour pixel-by-pixel: the three inputs (rinp, ginp and binp) are simultaneously sampled for each pixel and a separate channel processes each i nput. the signals are then multiplexed into the adc, which converts all three inputs within the pixel period. two channel pixel-by-pixel: two input channels (rinp and ginp) are simultaneously sampled for each pixel and a separate channel processes each i nput. the signals are then multiplexed into the adc, which converts both inputs within the pi xel period. the unused blue channel is powered down when this mode is selected. monochrome: a single chosen input (rinp, ginp, or binp) is sampled, processed by the corresponding channel, and converted by the adc. the choice of input and channel can be changed via the control interface, e.g. on a line-by-li ne basis if required. the unused channels are powered down when this mode is selected. wm8215 production data w pd, rev 4.3, september 2012 14 reset level clamping (rlc) to ensure that the signal applied to the wm8215 lies within the supply voltage range (0v to avdd) the output signal from a ccd is usually leve l shifted by coupling through a capacitor, c in. the rlc circuit clamps the wm8215 side of this capacitor to a suitable voltage through a cmos switch during the ccd reset period (pixel clamping) or during the bl ack pixels (line clamping). in order for clamping to produce correct results the input voltage dur ing the clamping must be a constant value. the wm8215 allows the user to control the rlc switch in a variety of ways as illustrated in figure 8 this figure shows a single channel, however all 3 channels are identical, each with its own clamp switch controlled by the common clmp signal. the method of control chosen depends upon the charac teristics of the input video. the rlcen register bit must be set to 1 to enable clamping, otherwise the rlc switch cannot be closed (by default rlcen=1). note that unused inputs should be left floating, or grounded through a decoupling capacitor, if reset level clamping is used. figure 8 rlc clamp control options when an input waveform has a stable reference le vel on every pixel it may be desirable to clamp every pixel during this period. setting clampc trl=0 means that the rlc switch is closed whenever the rsmp input pin is high, as shown in figure 9. mclk vsmp rsmp rlc switch control "clmp" (rlcen=1,clmpctrl=0) rlc switch closed when rsmp=1 video sample taken on fallling edge of vsmp reset/reference sample taken on fallling edge of rsmp input video signal reference ("black") level video level figure 9 reset level clamp operation (clampctrl =0), cds operation shown, non-cds also possible wm8215 production data w pd, rev 4.3, september 2012 15 in situations where the input video signal does not have a stable reference level it may be necessary to clamp only during those pixels which have a known state (e.g. the dummy, or ?black? pixels at the start or end of a line on most image sensors). this is known as line-clamping and relies on the input capacitor to hold the dc level between clamp inte rvals. in non-cds mode (cds=0) this can be done directly by controlling the rsmp input pin to go high during the black pixels only. alternatively it is possible to use rsmp to ident ify the black pixels and enable the clamp at the same time as the input is being sampled (i.e. when vsm p is high and rsmp is hi gh). this mode is enabled by setting clampctrl=1 and the operation is shown in figure 10. mclk vsmp rsmp rlc switch control, "clmp" (rlcen=1,clmpctrl=1) rlc switch closed when rsmp=1 && vsmp=1 (during "black" pixels) video and reference sample taken on fallling e dge of vsmp input video signal unstable reference level dummy or "black" pixel video level figure 10 reset level clamp operation (clampctrl=1), non-cds mode only rlcen clampctrl outcome use 0 x rlc is not enabled. rlc switch is always open. when input is dc coupled and within supply rails. 1 0 rlc switch is controlled directly from rsmp input pin: rsmp=0: switch is open rmsp=1: switch is closed when user explicitly provides a reset sample signal and the input video waveform has a suitable reset level. 1 1 vsmp applied as normal, rsmp is used to indicate the location of black pixels rlc switch is controlled by logical combination of rsmp and vsmp: rsmp && vsmp = 0: switch is open rsmp && vsmp = 1: switch is closed when clamping during the video period of black pixels or there is no stable per-pixel reference level. this method of operation is generally only sensible in non-cds mode. table 2 reset level clamp control summary wm8215 production data w pd, rev 4.3, september 2012 16 cds/non-cds processing for ccd type input signals, containi ng a fixed reference/reset level, the signal may be processed using correlated double sampling (cds), which will remove pixel-by-pixel common mode noise. with cds processing the input waveform is sampled at two different points in time for each pixel, once during the reference/reset level and once during the vi deo level. to sample using cds, register bit cds must be set to 1 (default). this causes the signal reference to come from the video reference level as shown in figure 11. the video sample is always taken on the falli ng edge of the input vsmp signal (vs). in cds-mode the reset level is sampled on the falling edge of the rsmp input signal (rs). for input signals that do not contain a referenc e/reset level (e.g. cis sensor signals), non-cds processing is used (cds=0). in this case, the video level is processed with respect to the voltage on pin vrlc/vbias. the vrlc/vbias voltage is samp led at the same time as vsmp samples the video level in this mode. figure 11 cds/non-cds input configuration offset adjust and programmable gain the output from the cds block is a differential si gnal, which is added to the output of an 8-bit offset dac to compensate for offsets and then amplified by a 9-bit pga. the gain and offset for each channel are independently programmable by writing to control bits dac[7:0] and pga[8:0]. the gain characteristic of the wm8215 pga is s hown in figure 12. figure 13 shows the maximum device input voltage that can be gained up to matc h the adc full-scale input range (default=2v). wm8215 production data w pd, rev 4.3, september 2012 17 0 1 2 3 4 5 6 7 8 0 128 256 384 512 gain code (pga[8:0]) pga gain (v/v) 0 0.5 1 1.5 2 2.5 3 3.5 0 128 256 384 512 gain code (pga[8:0]) input voltage range (v) max i/p v oltage lowrefs=0 max i/p v oltage lowrefs=1 figure 12 pga gain characteristic figure 13 peak input voltage to match adc full-scale range adc input black level adjust the output from the pga can be offset to match t he full-scale range of the differential adc (2*[vrt- vrb]). for negative-going input video signals, a black level (z ero differential) output from the pga should be offset to the top of the adc range by setting regist er bits pgafs[1:0]=10. this will give an output code of 3ff (hex) from the wm8215 for zero input. if code zero is required for zero differential input then the invop bit should be set. for positive going input signals the black level shoul d be offset to the bottom of the adc range by setting pgafs[1:0]=11. this will give an output code of 000 (hex) from the wm8215 for zero input. figure 14 adc input black level adjust settings wm8215 production data w pd, rev 4.3, september 2012 18 overall signal flow summary figure 15 represents the processing of the video signal through the wm8215. v reset v vrlc v 3 cds = 1 cds = 0 cdacpd=1 255mv*(dac[7:0]-127.5)/127.5 analog - x + + see parametrics for dac voltages. op[9:0] d 1 digital adc block pga block offset dac block input sampling block d 2 cds, cdacpd,cdac[3:0], dac[7:0], pga[8:0], pgafs[1:0] and invop are set by programming internal control registers. cds=1 for cds, 0 for non-cds v in is rinp, ginp or binp v reset is v in sampled during reset clamp v rlc is voltage applied to vrlc/vbias pin v in x (1023/v fs ) +0 if pgafs[1:0]=11 +1023 if pgafs[1:0]=10 pga gain a= 0.66+pga[8:0]x7.34/511 output invert block d2 = d1 if invop = 0 d2 = 1023-d1 if invop = 1 offset dac rlc dac + v 2 v 1 cdacpd=0 figure 15 overall signal flow the input sampling block produces an effective input voltage v 1 . for cds, this is the difference between the input video level v in and the input reset level v reset . for non-cds this is the difference between the input video level v in and the voltage on the vrlc/vbias pin, v vrlc , optionally set via the rlc dac. the offset dac block then adds the amount of fine offset adjustment required to move the black level of the input signal towards 0v, producing v 2 . the pga block then amplifies the white level of the input signal to maximise the adc range, outputting voltage v 3 . the adc block then converts the analogue signal, v 3 , to a 10-bit unsigned digital output, d 1 . the digital output is then inverted, if required, through the output invert block to produce d 2. wm8215 production data w pd, rev 4.3, september 2012 19 calculating the output code for a given input the following equations describe the processi ng of the video and reset level signals through the wm8215. input sampling block: input sampling and referencing if cds = 1, (i.e. cds operation) the previously sampled reset level, v reset , is subtracted from the input video, v in (= rinp, ginp or binp). v 1 = v in - v reset eqn. 1 if cds = 0, (non-cds operation) the simultaneously sampled voltage on pin vrlc is subtracted instead. v 1 = v in - v vrlc eqn. 2 if vrlcdacpd = 1, v vrlc is an externally applied voltage on pin vrlc/vbias. if vrlcdacpd = 0, v vrlc is the output from the internal rlc dac. v vrlc = (v rlcstep ? rlc dac[3:0]) + v rlcbot eqn. 3 v rlcstep is the step size of the rlc dac and v rlcbot is the minimum output of the rlc dac. offset dac block: off set (black-level) adjust the resultant signal v 1 is added to the offset dac output. v 2 = v 1 + {255mv ? (dac[7:0]-127.5) } / 127.5 eqn. 4 pga node: gain adjust the signal is then multiplied by the pga gain. v 3 = v 2 ? (0.66 + pga[8:0]x7.34/511) eqn. 5 adc block: analogue-digital conversion the analogue signal is then convert ed to a 10-bit unsigned number, with input range configured by pgafs[1:0]. d 1 [9:0] = int{ ( v 3 /v fs ) ? 1023} pgafs[1:0] = 11 eqn. 7 d 1 [9:0] = int{ ( v 3 /v fs ) ? 1023} + 1023 pgafs[1:0] = 10 eqn. 8 where the adc full-scale range, v fs = 2v when lowrefs=0 and v fs = 1.2v when lowrefs=1. output invert block: polarity adjust the polarity of the digital output may be inverted by control bit invop. d 2 [9:0] = d 1 [9:0] (invop = 0) eqn. 9 d 2 [9:0] = 1023 ? d 1 [9:0] (invop = 1) eqn. 10 wm8215 production data w pd, rev 4.3, september 2012 20 references the adc reference voltages are derived from an internal bandgap reference, and buffered to pins vrt and vrb where they must be decoupled to ground. pin vrx is driven by a similar buffer, and also requires decoupling. the output buffer from the rlcdac also requires decoupling at pin vrlc/vbias. the adc references can be switched from the def ault values (vrt=2.05v, vrb=1.05v, adc input range=2v) to give a smaller adc reference r ange (vrt=1.85v, vrb=1.25v, adc input range=1.2v) under control of the lowrefs register bit. setti ng lowrefs=1 allows smaller input signals to be accommodated. note: when lowrefs = 1 the output of the rlcdac will sca le if rlcdacrng = 1. the max output from rlcdac will change from 2.05 to 1.85v and the step size will proportionally reduce. power management power management for the device is performed via the c ontrol interface. by default the device is fully enabled. the en bit allows the device to be fully powered down when set low. individual blocks can be powered down using the bits in setup register 5. when in one or two channel mode the unused input channels are automatically dis abled to reduce power consumption. line-by-line operation certain linear sensors give colour output on a line-by- line basis (i.e. a full line of red pixels followed by a line of green pixels followed by a line of blue pixe ls). often the sensor will have only a single output onto which these outputs are time multiplexed. the wm8215 can accommodate this type of input by se tting the linebyline register bit high. when in this mode the green and blue input pgas are disabled to save power. the analogue input signal should be connected to the rinp pin. the offset and gain values that are applied to the red input channel can be selected, by internal multiplexers, to come from the red, green or blue offset and gain registers. this allows the gain and offset values for each of the input colours to be setup individually at the start of a scan. when register bit acyc=0, the gain and offset multip lexers are controlled via the intm[1:0] register bits. when intm=00, the red offs et and gain control registers are used to control the red input channel. likewise, intm=01 selects the green o ffset and gain registers and intm=10 selects the blue offset and gain registers to control the red input channel. when register bit acyc=1, ?auto-cy cling? is enabled, and the input channel switches to the next offset and gain registers in the sequence when a pulse is app lied to the rsmp input pin. the sequence is red ? green ? blue ? red? offset and gain registers applied to the single input channel. a write to the auto-cycle reset register (address 05h) w ill reset the sequence to a known state (red registers selected). when auto-cycling is enabled, the rsmp pin alone c annot be used to control reset level clamping. reset level clamping may be enabled in this situat ion by setting the clampctrl and rlcen bits so that the logical and of rsmp and vsmp closes the clamp switch. additionally, when auto-cycling is enabled, the rsmp pin cannot be used for reset sampling (i.e. cds must be set to 0). control interface the internal control registers are programmable via the serial digital control interface. the register contents can be read back via the seri al interface on pin op[9]/sdo. it is recommended that a software reset is carried out after the power-up sequence, before writing to any other register. this ensures t hat all registers are set to their default values (as shown in table 5). wm8215 production data w pd, rev 4.3, september 2012 21 serial interface: register write figure 16 shows register writing in serial mode. three pins, sck, sdi and sen are used. a six-bit address (a5, 0, a3, a2, a1, a0) is clocked in through sdi, msb first, followed by an eight-bit data word (b7, b6, b5, b4, b3, b2, b1, b0), also msb first. se tting address bit a4 to 0 indicates that the operation is a register write. each bit is latched on the rising edge of sck. when the data has been shifted into the device, a pulse is applied to sen to transfer the data to the appropriate internal register. sck sen sdi a5 0 a3a2a1a0b7b6b5b4b3b2b1b0 address data word figure 16 serial interface register write a software reset is carried out by writing to address ?000100? with any value of data, (i.e. data word = xxxxxxxx). serial interface: register read-back figure 17 shows register read-back in serial mode. r ead-back is initiated by writing to the serial bus as described above but with address bit a4 set to 1, followed by an 8-bit dummy data word. writing address (a5, 1, a3, a2, a1, a0) will cause the contents (d7, d6, d5, d4, d3, d2, d1, d0) of corresponding register (a5, 0, a3, a2, a1, a0) to be output msb first on pin sdo (on the falling edge of sck). note that pin sdo is shared with an output pin, op[9], therefore oeb should always be held low and the opd register bit should be set low when register read-back data is expected on this pin. the next word may be read in to sdi while the previous word is still being output on sdo. figure 17 serial interface register read-back wm8215 production data w pd, rev 4.3, september 2012 22 normal operating modes table 3 below shows the normal operating modes of the device. the mclk speed can be specified along with the mclk:vsmp ratio to achieve the desired sample rate. number of channels description cds available maximum sample rate timing requirements channel mode settings 3 three channel pixel-by-pixel yes 20 msps mclk max = 60mhz minimum mclk:vsmp ratio = 3:1 mono = 0 twochan = 0 2 two channel pixel-by-pixel yes 30 msps mclk max = 60mhz minimum mclk:vsmp ratio = 2:1 mono = 0 twochan = 1 1 one channel pixel-by-pixel yes 45 msps mclk max = 45mhz minimum mclk:vsmp ratio = 1:1 mono = 1 twochan = 0 table 3 wm8215 normal operating modes note : in one channel mode the wm8215 can operate at 60mhz but dnl/inl values cannot be guaranteed. table 4 below shows the different channel mode regi ster settings required to operate the 8215 in 1, 2 and 3 channel modes. mono twochan chan[1:0] mode description 0 0 xx 3-channel (colour mode) 0 1 xx 2-channel (blue pga disabled) 1 0 00 1-channel (monochrome) mode. red channel selected, green and blue pgas disabled. 1 0 01 1-channel (monochrome) mode. green channel selected, red and blue pgas disabled. 1 0 10 1-channel (monochrome) mode. blue channel selected, red and green pgas disabled. 1 0 11 invalid mode 1 1 xx invalid mode table 4 sampling mode summary note : unused input pins should be connected to agnd, unless reset level clamping is used. wm8215 production data w pd, rev 4.3, september 2012 23 device configuration register map the following table describes the location of each control bit used to determine the operation of the wm8215. addres s wm8215 production data w pd, rev 4.3, september 2012 24 register map description the following table describes the function of each of the control bits shown in table 5 address wm8215 production data w pd, rev 4.3, september 2012 25 address wm8215 production data w pd, rev 4.3, september 2012 26 address wm8215 production data w pd, rev 4.3, september 2012 27 address wm8215 production data w pd, rev 4.3, september 2012 28 applications information recommended external components figure 18 external components diagram recommended external component values component reference suggested value description c1 100nf de-coupling for dvdd1. c2 100nf de-coupling for dvdd2. c3 100nf de-coupling for avdd. c5 1 ? f ceramic de-coupling between vrt and vrb (non-polarised). c6 100nf de-coupling for vrb. c7 100nf de-coupling for vrx. c8 100nf de-coupling for vrt. c9 100nf de-coupling for vrlc. c10 10 ? f reservoir capacitor for dvdd1. c11 10 ? f reservoir capacitor for dvdd2. c12 10 ? f reservoir capacitor for avdd. table 7 external components descriptions wm8215 production data w pd, rev 4.3, september 2012 29 package dimensions dm101.a fl: 32 pin qfn plastic package 5 x 5 x 0.9 mm body, 0.50 mm lead pitch e2 b b 16 15 8 9 e c 0.08 c ccc a a1 c a3 seating plane 1 l index area (d/2 x e/2) top view d c aaa 2 x c aaa 2 x e 1 17 24 25 32 d2 b c bbb m a 5 4 notes: 1. dimension b applies to metallized terminal and is measured between 0.15 mm and 0.30 mm from terminal tip. 2. falls within jedec, mo-220, variation vhhd-5. 3. all dimensions are in millimetres. 4. the terminal #1 identifier and terminal numbering convention shall conform to jedec 95-1 spp-002. 5. coplanarity applies to the exposed he at sink slug as well as the terminals. 6. refer to application note wan_0118 for further information regarding pcb footprints and qfn package soldering. 7. this drawing is subject to change without notice. detail 1 a3 g t h w b exposed lead half etch tie bar dimensions (mm) symbols min nom max note a a1 a3 0.80 0.90 1.00 0.05 0.02 0 0.203 ref b d d2 e e2 e l 0.30 0.18 5.00 bsc 3.60 3.45 3.30 0.50 bsc 0.30 0.40 0.50 1 2 2 5.00 bsc 3.60 3.45 3.30 0.10 aaa bbb ccc ref: 0.15 0.10 jedec, mo-220, variation vhhd-5. tolerances of form and position 0.25 h 0.1 0.20 g t 0.103 w 0.15 detail 1 detail 2 detail 2 exposed ground paddle 6 exposed ground paddle bottom view side view 0.30 45 m m wm8215 production data w pd, rev 4.3, september 2012 30 important notice wolfson microelectronics plc (?wol fson?) products and services are sold subject to wolfson?s terms and conditions of sale, delivery and payment supplied at the time of order acknowledgement. wolfson warrants performance of its products to the specifications in effect at t he date of shipment. wolfson reserves the right to make changes to its products and s pecifications or to discontinue any produc t or service without notice. customers should therefore obtain the latest version of relevant informati on from wolfson to verify that the information is current. testing and other quality control techniques are utilised to the extent wolfson deems necessary to support its warranty. specific testing of all parameters of each device is not necessarily performed unless requi red by law or regulation. in order to minimise risks associated with customer app lications, the customer must use adequate design and operating safeguards to minimise inherent or proc edural hazards. wolfson is not liable fo r applications assistance or customer product design. the customer is solely responsible for its se lection and use of wolfson products . wolfson is not liable for such selection or use nor for use of any circuitry other than circuitry entirely embodied in a wolfson product. wolfson?s products are not intended for use in life support systems, appliances, nuclear systems or systems where malfunction can reasonably be expected to re sult in personal injury, death or severe property or environmental damage. any use of products by the customer for such purposes is at the customer?s own risk. wolfson does not grant any licence (express or implied) under any patent right, copyright, mask work right or other intellectual property right of wolfson covering or relating to any combination, machine, or pr ocess in which its products or services might be or are used. any prov ision or publication of any third party?s products or services does not constitute wolfson?s approval, licence, warranty or endorsement thereof. any third party trade marks contained in this document belong to the respective third party owner. reproduction of information from wolfson datasheets is per missible only if reproduction is without alteration and is accompanied by all associated copyright, proprietary and other not ices (including this notice) and conditions. wolfson is not liable for any unauthorised alteration of such in formation or for any reliance placed thereon. any representations made, warranties giv en, and/or liabilities accepted by any pers on which differ from those contained in this datasheet or in wolfson?s standard terms and conditions of sale, delivery and payment are made, given and/or accepted at that person?s own risk. wolfson is not liable for any such representations, warranties or liabilities or for any reliance placed thereon by any person. address: wolfson microelectronics plc westfield house 26 westfield road edinburgh eh11 2qb tel :: +44 (0)131 272 7000 fax :: +44 (0)131 272 7001 email :: sales@wolfsonmicro.com wm8215 production data w pd, rev 4.3, september 2012 31 revision history date rev originator changes 04/09/12 4.3 jmacd order codes changed from wm8215sefl and wm8215sefl/r to wm8215csefl and wm8215csefl/r to reflect change to copper wire bonding. 04/09/12 4.3 jmacd package diagram changed to dm101.a |
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