1 features buffered speed sensor output no cross-conduction in either h-bridge guaranteed monotonic on chip flyback diodes fault protection overvoltage short circuit protection load dump protection to 60v package options 8 lead pdip cs8442 stepper motor driver with buffered speed signal output 1 gnd coila+ coila sensor in v cc coilb+ coilb sensor out description block diagram absolute maximum ratings cs8442 december, 2001 - rev. 2 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 cs8442 is a stepper motor driver that implements an h- bridge design to drive two coils in an eight step sequence each revo- lution. each h-bridge is capable of delivering 85ma to the load. the sequencer function insures that the odometer is monotonic and that cross-conduction of each h bridges does not occur. before the beginning of each sequence, both bridges are turned off. this ?ead zone?minimizes the fly back energy generated in the inductive loads. in addition, on board clamp diodes across each output protect the output drive transistors from excessive fly back voltages. the cs8442 is fault protected against reverse battery, short cir- cuit, and over voltage conditions. if a fault is detected, the ic shuts down. the buffered speed signal output (sensor out) is an open collec- tor npn capable of driving a 4.7k ? load connected to a 5v sup- ply. the signal is a buffered, inverted version of the speed sen- sor input voltage (sensor in). the input voltage can be either a sine or square wave form. supply voltage (v cc ) (continuous) -40?c to +105?c ..................?.5 to 24v (100ms pulse transient) -40?c to +105?c ......................?.5 to 60v input voltage (v in ) ..............................................................?.3 to v cc +0.3v storage temperature range (t stg )......................................?5? to +150? junction temperature.............................................................?0? to +150? speed sensor output .....................................................................................7v esd (human body model) .........................................................................2kv lead temperature soldering wave solder (through hole styles only) ........10 sec. max, 260? peak coilb- sensor in sensor out coil driver b coil driver a overvoltage and short circuit protection sequencer coilb + coila- coila+ input comp.
2 cs8442 electrical characteristics: unless otherwise stated, these specifications apply for -40?c to +105?c, v cc = 6.5 to 15.5 vdc. all voltage shall be referenced to gnd unless otherwise noted. overvoltage shutdown of coils occurs when v cc > 16v. parameter test conditions min typ max unit * voltage across the coils shall be measured at the specific voltages, but shall also be within linearly interpolated limits. supply supply voltage range t a = -40? to +105? 6.5 15.5 t a = -40? to +25? 6.5 24.0 supply current v cc = 15.5 vdc 35 ma outputs not loaded overvoltage shutdown 16 23 v speed sensor input frequency range 0 400 hz switching threshold 1.6 3.0 vdc hysteresis 300 mv input bias current v in = 0.8vdc to v cc ? a input voltage range 0 8 vdc operating input voltage 10k ohm resistor in series -15 vdc to v cc output saturation voltage i cc = 1.3ma 0.4 v output leakage v cc = 5.5v 10 a input clamp current i clamp at v in = 0 vdc -0.4 -5.0 ma coil output drivers coil load +25? 198 210 222 ? coil inductance 80 mh coil resistance temperature coefficient 0.39 %/? * energized coil voltage (both polarities) a and b v cc = 6.5 vdc v cc - 1.50 vdc v cc = 10.0 vdc v cc - 1.60 vdc v cc = 15.5 vdc, t a = -20? to +105? v cc - 1.75 vdc v cc = 15.5 vdc, t a = -40? to -20? v cc - 2.00 vdc de-energized coil leakage 100 a current short circuit protection short circuit threshold 275 400 ma coil a + coil b short circuit turn off delay 5 s
3 sensor in is a pnp comparator input that accepts a sine or square wave input. signals in excess of v cc or ground will not damage the input as long as the input current is limited to 1.5ma. an active clamp at 0v prevents negative input voltages from disrupting normal operation. the input can withstand 150 vdc as long as the input current does not exceed 1.5ma. this is possible if a 100k ? resistor is placed in series with the sensor in. sensor out is an open collector npn transistor that produces a buffered and inverted version of the sensor in signal. it is capable of driving a 4.7k ? load connected to a 5v supply. the eight step sequencer moves the two h bridge output drivers through 8 sequential states (table 1, figure 1). in state 0, current flows from coila+ out through coil a and back in through coila-. the same polarity also holds for coil b. in state 1, coil a outputs turn off while coil b outputs continue con- ducting with the same polarity. in state 2, current flows from coil a- out through the coil and back in coil a+. coil b out- puts continue with their original polarity. coil a outputs maintain this polarity through states 3 and 4 during which coil b outputs are first turned off and then reversed. coil b? reversed polarity continues in stages 5 and 6. coil a? outputs are turned off in stage 5 and then turned back on (positive polarity) in stage 6. in stage 7, coil b is off and coila outputs continue with a positive polarity. table 1: transition states the polarity definition for the coil driver outputs is as follows: connect connect polarity coil + coil - positive (+) v cc gnd negative (-) gnd v cc each h-bridge output stage consists of 4 power npn transistors with fly back diodes (figure 2). each half bridge has a composite saturation voltage of 1.5v at v cc =15.5v and i out = 85ma. the output stage is designed to prevent cross conduction: i.e., at no time can q1 and q2 or q3 and q4 conduct. this dead zone time minimizes fly back energy and helps protect the output stages from damage. the cs8442 is protected from short circuit, over voltage and thermal runaway conditions. when any of these faults is detect- ed, an internal flip-flop is set and both h bridges are disabled. when the fault condition is removed, the flip-flop is reset after the first positive going edge from the speed sensor input. cs8442 package pin description application information speed sensor sequencer h bridge outputs a and b protection circuitry package pin # pin symbol function 8l pdip 1 gnd ground connection. 2 coila+ output stage, when active, supplies current to coil a. 3 coila- output stage, when active, supplies current to coil a. 4 sensor in input signal from wheel speed or engine rpm. 5 sensor out buffered and inverted output of sensor in signal. 6 coilb- output stage, when active, supplies current to coil b. 7 coilb+ output stage, when active, supplies current to coil b. 8v cc supply voltage. short circuit v cc sense resistor coil short circuit sense resistor gnd q3 q4 q1 q2 overvoltage and short circuit protection figure 2: coil driver output figure 1: state diagram for coil outputs 0 1 2 3 4 5 6 7 0 coil a coil b + + state # output state table state coil a coil b 0++ 1 off + 2-+ 3 - off 4-- 5 off - 6+- 7 + off
4 part number description cs8442xn8 8l pdip package specification application diagram package dimensions in mm (inches) ordering information package thermal data cs8442 c1 - 10 f c2 - 0.1 f c3 - 0.01 f r1 - 3.9 ? 0.5w r2 - 100k ? r3 - 15k ? d1 - 1a 600piv z1 - 50v 0.5w coil a - 210 12 ? , 80mh coil b - 210 12 ? , 80mh 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 d lead count metric english max min max min 8l pdip 10.16 9.02 .400 .355 thermal data 8l pdip r jc typ 52 ?c/w r ja typ 100 ?c/w 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) plastic dip (n); 300 mil wide coila+ coila coilb+ coilb v cc sensor out gnd sensor in cs8442 ign d1 r1 r3 z1 c1 c2 r2 c3 buffered speed signal (open collector drive)
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