features v cc control output gnd gnd gnd gnd duty cycle during short circuit overtemp shutdown short circuit detect open circuit detect i source v cc(sense) drive & bias + + - - fault fault detection open circuit short circuit over temperature v cc sense: output turns on with loss of v cc low standby current package options cs1108 single lamp driver ic cs1108 description this asic provides up to 350ma of drive current for powering bulbs. the typical application for this part is for use in airbag systems using a type 194 bulb. on chip diagnostics provide open circuit and short cir- cuit detection in the output on mode. in addition, the output driver will turn on (sink current) when v cc is low. is an active-low output which reports in the output-on mode. internal pull- up circuitry is provided to ensure the output pin turns on when the control pin is floating. fault block diagram absolute maximum ratings storage temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65 ? c to 150 ? c v cc , , control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5v to 6v esd capability (human body model). . . . . . . . . . . . . . . . . . . . . . . . . . . 2kv peak transient voltage (output off mode, output pin only) (26v load dump @ 14v v bat ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40v lead temperature soldering reflow (smd styles only) . . . . 60 sec. max above 183c, 230c peak fault output 1 v cc gnd gnd control gnd gnd fault 8 lead so (internally fused leads) 1 rev. 6/23/99 cherry semiconductor corporation 2000 south county trail, east greenwich, ri 02818 tel: (401)885-3600 fax: (401)885-5786 email: info@cherry-semi.com web site: www.cherry-semi.com a company ?
electrical characteristics: 4.75v v cc 5.25v, -40c t a 85c; -40 t j 150c cs1108 2 package pin description package pin # pin symbol function parameter test conditions min typ max unit 8 lead so narrow 1 output open collector output. 2v cc 5v regulated supply input. 3 open collector diagnostic output low during open load, short circuit and overtemperature conditions. 4 control ttl compatible input. 5, 6, 7, 8 ground signal ground. fault supply requirements v cc quiescent current output on 3 6 ma v cc quiescent current output off 100 250 a output leakage current v bat =14v 16 100 a saturation voltage i output = 350ma 1.1 1.5 v i output = 180ma 0.9 1.3 v v output (self-bias) v cc < 4.5v, i output < 200ma 3.5 v current sense short circuit current 350 500 650 ma open circuit current output in the on state 20 40 60 ma control - input input voltage logic = high 2.0 v logic = low 0.8 v input current logic = v cc 20 40 a logic = 0v -50 -20 a fault output - (open collector) output low voltage i fault = 250a (sink) 0.24 0.40 v overtemperature shutdown t j output disable threshold (guaranteed by design) 150 180 ? c t j hysteresis (guaranteed by design) 5 ? c note: a fault signal will be shown (at the fault pin) during inrush as the short circuit threshold is exceeded.
cs1108 3 v bat v cc output gnd v cc control gnd cs1108 gnd gnd fault microprocessor 20k 10nf applications diagram circuit description the cs1108 lamp driver ic provides up to 350ma of drive current in a low-side configuration. the output driver pin is controlled through the ttl compatible control input pin. a high condition on the control pin turns the output pin on. the pin reports short circuit, open circuit, and overtemperature conditions on the ic. if a fault is present, the open collector output pin will be low. typical numbers for faults are: exceeding 500ma of drive current will report a short circuit. less than 40ma (typical) will report an open circuit. a temperature fault will be reported when the die temperature exceeds 180c (typical). faults are only reported when the control pin is high, due to the low quiescent current when the control pin is low and the output device is turned off. the cs1108 is designed to provide overcurrent protection by duty cycle control. when the lamp current exceeds the internally programmed current limit threshold (typically 500ma), the output enters duty cycle mode to reduce power dissipation of the ic to a safe level. typical lamps have a low resistance when off and the cur- rent will exceed the current limit threshold during the ini- tial inrush period. during this inrush time, the ic will be operating in the duty cycle mode. due to characteristics of lamps in this mode, they may appear dimly lit. this condi- tion will persist for a brief time until the lamp resistance has increased enough to reduce it?s current below the threshold. once this occurs the lamp will appear at full brightness. during the inrush period the fault pin will be forced low indicating that duty cycle mode is in operation. thermal protection has been designed into this ic. should duty cycle mode operate for an extended amount of time and the power limitations of the ic are exceeded the ic die temperature will rise. once the die temperature reaches the thermal temperature limit, the internal circuitry will shut- off the output and the lamp will turn off. once the die tem- perature lowers below the thermal threshold then the out- put will be allowed to turn back on. fault fault
thermal data 8 lead so narrow (internally fused leads) r jc typ 25 ? c/w r ja typ 110 ? c/w 4 1.27 (.050) bsc 0.51 (.020) 0.33 (.013) 6.20 (.244) 5.80 (.228) 4.00 (.157) 3.80 (.150) 1.57 (.062) 1.37 (.054) d 0.25 (0.10) 0.10 (.004) 1.75 (.069) max 1.27 (.050) 0.40 (.016) ref: jedec ms-012 0.25 (.010) 0.19 (.008) 8 lead so narrow; 150 mil wide rev. 6/23/99 ? 1999 cherry semiconductor corporation package specification package dimensions in mm (inches) d lead count metric english max min max min 8 lead so narrow 5.00 4.80 .197 .189 package thermal data cs1108 ordering information part number description cs1108edf8 8 lead so narrow (internally fused leads) CS1108EDFR8 8 lead so narrow (internally fused leads) (tape & reel) cherry semiconductor corporation reserves the right to make changes to the specifications without notice. please contact cherry semiconductor corporation for the latest available information.
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