1 features serial input bus 2mhz operating frequency tangential drive algorithm 80ma drive circuits 0.5 accuracy (typ.) power-on-reset protection features output short circuit overtemperature package options single air-core gauge driver cs4172 description block diagram 16 lead pdip sin - sin + gnd v bb gnd nc so si v cc cos + cos - cs sclk oe 1 gnd st sin - sin + gnd v bb gnd gnd so si v cc cos + cos - cs sclk oe 1 gnd st 16 lead so wide internally fused leads december, 2001 - rev. 3 cs4172 on semiconductor 2000 south county trail, east greenwich, ri 02818 tel: (401)885?600 fax: (401)885?786 n. american technical support: 800-282-9855 web site: www.cherry?emi.com archive device not recommended for new design the cs4172 is a monolithic bicmos integrated circuit used to translate a digital 10-bit word from a micropro- cessor/microcontroller to complemen- tary dc outputs. the dc outputs drive an air-core meter commonly used in vehicle instrument panels. the 10 bits of data are used to linearly con- trol the quadrature coils of the meter directly with a 0.35 resolution and 1.0 accuracy over the full 360 range of the gauge. the interface from the microcontroller is by a serial periph- eral interface (spi) compatible serial connection using up to a 2mhz shift clock rate. the digital code, which is directly pro- portional to the desired gauge pointer deflection, is shifted into a dac and multiplexer. these two blocks provide a tangential conversion function to change the digital data into the appro- priate dc coil voltage for the angle demanded. the tangential algorithm creates approximately 40% more torque in the meter movement than does a sin-cos algorithm at 45? 135? 225? and 315 angles. this increased torque reduces the error due to pointer droop at these critical angles. each output buffer is capable of sup- plying up to 80ma per coil and are controlled by a common enable pin. when oe is low the output buffers are turned off but the logic portion of the chip remains powered and continues to operate normally. the serial gauge driver is self-protect- ed against output short circuit condi- tions. the output drivers are disabled anytime the on-chip protection circuit- ry detects a short circuit condition. the outputs remain off until a falling edge is presented on cs. if the short circuit is still present the output drivers auto- matically disable themselves again. a thermal protection circuit limits the junction temperature to approximately 160? for conditions of high supply voltage and high ambient temperature. the status pin (st) reflects the state of the outputs and is low whenever the outputs are disabled. output amplifiers gnd sclk si cos cos + sin sin + v bb v cc por serial to parallel shift register por oc 7 bit dac so d0 ?d6 v top v var mux oe cs v bat fault latch logic st rs s d7 ?d9
2 absolute maximum ratings cs4172 electrical characteristics: ? 40? t a 105?; 7.5v v bb 14v; 4.5v v cc 5.5v; unless otherwise specified. parameter test conditions min typ max unit supply voltage v bb ............................................................................................................................... ................................... ? 1.0v to 15.0v v cc ............................................................................................................................... ..................................... ? 1.0v to 6.0v digital inputs ................................................................................................................. ........................................... ? 1.0v to 6.0v ground potential difference (|agnd-dgnd|)...................................................................................... ............................. 0.5v steady state output current .................................................................................................... ....................................... 100ma forced injection current (inputs and supply)................................................................................... ............................. 10ma operating junction temperature (t j ) .............................................................................................................................. ... 150? storage temperature range ..................................................................................................... ........................... ? 65? to 150? lead temperature soldering wave solder (through hole styles only) .................................................................................... 10 se c. max, 260? peak reflow (smd styles only) ..................................................................................... 60 sec. max above 183?, 230? peak esd susceptibility (human body model).......................................................................................... ................................... 2kv supply voltages and currents v bb quiescent current output disabled (oe = 0v) 1 5 ma [r cos , r sin = r l(min) ] @ 45 175 ma (code = x?80) v bb = 14v v cc quiescent current oe = high, v bb = 0v sclk = 2.0mhz 1 ma digital inputs and outputs output high voltage so, i oh = 0.8ma v cc ? 0.8 v output low voltage so, i ol =0.8ma 0.4 v st, i ol = 2.5ma 0.8 v output high current st, v cc = 5.0v 25 a input high voltage cs, sclk, si, oe 0.7 v cc v input low voltage cs, sclk, si, oe 0.3 v cc v input high current cs, sclk, si, oe; v in = 0.7 v cc 1 a input low current cs, sclk, si, oe; v in = 0.3 v cc 1 a analog outputs output function accuracy ? 1.2 +1.2 deg output shutdown current, v bb = 14.0v 70 250 ma source output shutdown current, v bb = 14.0v 70 250 ma sink output shutdown current, v bb = 7.5v 43 250 ma source output shutdown current, v bb = 7.5v 43 250 ma sink coil drive output voltage 0.748 v bb v minimum load resistance t a = 105? 229 ? t a = 25? 171 ? t a = ? 40? 150 ?
3 package pin description package pin# pin symbol function parameter test conditions min typ max unit electrical characteristics: ? 40? t a 105?; 7.5v v bb 14v; 4.5v v cc 5.5v; unless otherwise specified. cs4172 shift clock frequency 2.0 mhz sclk high time 175 ns sclk low time 175 ns so rise time 0.75v to v cc ? 1.2v; c l = 90pf 150 ns so fall time 0.75v to v cc ? 1.2v; c l = 90pf 150 ns so delay time c l = 90pf 150 ns si setup time 75 ns si hold time 75 ns cs setup time 0 ns cs hold time 75 ns 16 lead so wide 16 lead pdip 1 1 sin ? negative output for sine coil. 2 2 sin + positive output for sine coil. 34v bb analog supply. nominally 13.5v. 4,5,12,13 3,13,14 gnd ground. 6 6 si serial data input. data present at the rising edge of the clock signal is shifted into the internal shift register. 77v cc 5v logic supply. the internal registers and latches are reset by a por generated by the rising edge of the voltage on this pin. 8 8 oe controls the state of the output buffers. a logic low on this pin turns them off. 9 9 sclk serial clock for shifting in/out of data. rising edge shifts data on si into the shift register and the falling edge changes the data on so. 10 10 cs when high allows data at si to be shifted into part with the rising edges of sclk. the falling edge transfers the shift register contents into the dac and multiplexer to update the output buffers. the falling edge also re-enables the output drivers if they have been disabled by a fault. 11 11 st status reflects the state of the outputs and is low any- time the outputs are disabled, either by oe or the internal protection circuitry. requires external pull-up resistor. 14 5 so serial data output. existing 10-bit data is shifted out when new data is shifted in. allows cascading of multiple devices on common serial port. 15 15 cos ? negative output for cosine coil. 16 16 cos + positive output for cosine coil. 12 nc no connection.
4 applications information cs4172 the sacd is for interfacing between a microcontroller or microprocessor and air-core meter movements commonly used in automotive vehicles for speedometers and tachometers. these movements are built using 2 coils placed at a 90 orientation to each other. a magnetized disc floats in the middle of the coils and responds to the magnetic field generated by each coil. the disc has a shaft attached to it that protrudes out of the assembly. a point- er indicator is attached to this shaft and in conjunction with a separate printed scale displays the vehicle? speed or the engine? speed. the disc (and pointer) respond to the vector sum of the voltages applied to the coils. ideally, this relationship fol- lows a equation. since this is a transcendental and non-linear function, devices of this type use an approxi- mation for this relationship. the sacd uses a tangential algorithm as shown in figure 1. only 1 output varies in any 45 degree range. figure 1. major gauge outputs. quadrant i = tan ? 1 for = 0.176 to 44.824? v sin = tan ? 0.748 v bb v cos = 0.748 v bb for = 45.176 to 89.824? v sin = 0.748 v bb v cos = tan(90 ) 0.748 v bb quadrant ii = 180 ?tan ? 1 for = 90.176 to 134.824? v sin = 0.748 v bb v cos = ? tan( ?90? 0.748 v bb for = 135.176 to 179.824? v sin = tan(180 ) 0.748 v bb v cos = ? 0.748 v bb quadrant iii = 180 + tan ? 1 for = 180.176 to 224.824? v sin = ? tan( ?180? 0.748 v bb v cos = ? 0.748 v bb for = 225.176 ?269.824? v sin = ? 0.748 v bb v cos = ? tan(270 ) 0.748 v bb quadrant iv = 360 ?tan ? 1 for = 270.176 to 314.824? v sin = ? 0.748 v bb v cos = tan( ?270? 0.748 v bb for = 315.176 ?359.824? v sin = ? tan(360 ) 0.748 v bb v cos = 0.748 v bb graph 1. major gauge response. ii v cos+ 360/0 i 270 v sin 90 v sin+ iii iv 180 v cos ? 0.748v bb 0.748v bb 0.748v bb 0.748v bb ] v sin+ ?v sin ? v cos+ ?v cos ? [ ] v sin+ ?v sin ? v cos+ ?v cos ? [ ] v sin+ ?v sin ? v cos+ ?v cos ? [ ] v sin+ ?v sin ? v cos+ ?v cos ? [ 0 45 90 135 180 225 270 315 360 max (128) min (0) max (128) min (0) max (128) min (0) max (128) min (0) sin + output sin output cos + output cos output degrees of rotation mux bits (d9 ?d7) 000 001 010 011 100 101 110 111 000 sine cosine theory of operation
cs4172 applications information: continued 5 application diagram enable cs4172 10k sclk si cos ? cos+ sin ? sin+ so oe cs st v bb v cc microcontroller next driver 360 gauge v bat v reg cs8156 5v 12v to drive the gauge? pointer to a particular angle, the microcontroller sends a 10-bit digital word into the serial port. these 10 bits are divided as shown in figure 2. however, from a software programmers viewpoint, a 360 circle is divided into 1024 equal parts of .35 each. table 1 shows the data associated with the 45 divisions of the 360 driver. figure 2. definition of serial word. table 1. nominal output for major gauge (v bb = 14v). the 10 bits are shifted into the device? shift register msb first using an spi compatible scheme. this method is shown in figure 3. the cs must be high and remain high for sclk to be enabled. data on si is shifted in on the ris- ing edge of the synchronous clock signal. data in the shift register changes at so on the falling edge of sclk. this arrangement allows the cascading of devices. so is always enabled. data shifts through without affecting the outputs until cs is brought low. at this time the internal dac is updated and the outputs change accordingly. figure 3. serial data timing diagram. figure 4. power-up sequence. 10 bits v cc cs si oe st 10 bits outputs enabled registers set to zero registers set to zero outputs enabled so (tpd) so (rise, fall) 10% - 90% si (hold) si (setup) sclk si so cs hold cs cs setup input code ideal nominal v sin v cos (decimal) degrees degrees (v) (v) 0 0 0.176 0.032 10.476 128 45 45.176 10.476 10.412 256 90 90.176 10.476 ? 0.032 384 135 135.176 10.412 ? 10.476 512 180 180.176 ? 0.032 ? 10.476 640 225 225.176 ? 10.476 ? 10.412 768 270 270.176 ? 10.476 0.032 896 315 315.176 ? 10.476 10.412 1023 359.65 359.826 ? 0.032 10.476 major gauge (360 ) d9 d8 d7 d6 d5 d4 d3 d2 d1 d0 d9 ?d7 select which octant divides a 45 octant into 128 equal parts to achieve a .35 resolution code 0 ?127 10 msb lsb
thermal 16 lead 16 lead data pdip so wide* r jc typ 42 18 c/w r ja typ 80 75 c/w cs4172 6 part number description cs4172xn16 16 lead pdip cs4172xdwf16 16 lead so wide* cs4172xdwfr16 16 lead so wide* (tape & reel) d lead count metric english max min max min 16 lead pdip 19.69 18.67 .775 .735 16 lead so wide* 10.50 10.10 .413 .398 ordering information package specification package dimensions in mm (inches) package thermal data *internally fused leads surface mount wide body (dw); 300 mil wide on semiconductor and the on logo are trademarks of semiconductor components industries, llc (scillc). on semiconductor reserves the right to make changes without further notice to any products herein. for additional infor- mation and the latest available information, please contact your local on semiconductor representative. ?semiconductor components industries, llc, 2000 archive device not recommended for new design plastic dip (n); 300 mil wide 0.39 (.015) min. 2.54 (.100) bsc 1.77 (.070) 1.14 (.045) d some 8 and 16 lead packages may have 1/2 lead at the end of the package. all specs are the same. .203 (.008) .356 (.014) ref: jedec ms-001 3.68 (.145) 2.92 (.115) 8.26 (.325) 7.62 (.300) 7.11 (.280) 6.10 (.240) .356 (.014) .558 (.022) 1.27 (.050) bsc 7.60 (.299) 7.40 (.291) 10.65 (.419) 10.00 (.394) d 0.32 (.013) 0.23 (.009) 1.27 (.050) 0.40 (.016) ref: jedec ms-013 2.49 (.098) 2.24 (.088) 0.51 (.020) 0.33 (.013) 2.65 (.104) 2.35 (.093) 0.30 (.012) 0.10 (.004)
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