CS1108

CS1108 CHERRY | Alldatasheet

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Technical content

Features

ISOURCEVCC(SENSE) Drive & Bias Fault n Fault Detection Open Circuit Short Circuit Over Temperature n V CC Sense: Output T urns On with Loss of VCC n 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 Peak Transient Voltage (output off mode, output pin only) (26V load Dump @ 14V V Lead Temperature Soldering Fault Output 1 VCC Gnd GndControl Gnd GndFault

8 Lead SO

(internally fused leads) 1Rev. 12/28/98 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 ² VCC ² 5.25V, -40¡C ² TA ² 85¡C; -40¡ ² TJ ² 150¡C CS1108 Package Pin Description PACKAGE PIN # PIN SYMBOL FUNCTION PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

8 Lead SO Narrow

1 Output Open collector output. 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 n Supply Requirements VCC Quiescent Current Output ON 3 6 mA VCC Quiescent Current Output OFF 100 250 µA n Output Leakage Current V BAT =14V 16 100 µA Saturation Voltage I OUTPUT = 350mA 1.1 1.5 V I OUTPUT = 180mA 0.9 1.3 V VOUTPUT (self-bias) V CC < 4.5V, I OUTPUT < 200mA 3.5 V n Current Sense Short Circuit Current 350 500 650 mA Open Circuit Current Output in the ON state 20 40 60 mA n Control - Input Input Voltage Logic = High 2.0 V Logic = Low 0.8 V Input Current Logic = V CC 20 40 µA Logic = 0V -50 -20 µA n Fault Output - (Open Collector) Output Low Voltage I FAULT = 250µA (sink) 0.24 0.40 V n Overtemperature Shutdown TJ Output Disable Threshold (guaranteed by design) 150 180 ûC TJ Hysteresis (guaranteed by design) 5 ûC Note: A fault signal will be shown (at the fault pin) during inrush as the short circuit threshold is exceeded.

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 180¡C (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 itÕs 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) RQJC typ 25 ûC/W RQJA typ 110 ûC/W 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. 12/28/98 © 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

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.