CS1108 CS1108 Single Lamp Driver IC Features 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 circuit detection in the output on mode. In addition, the output driver will turn on (sink current) when VCC is low. Fault is an active-low output which reports in the output-on mode. Internal pullup circuitry is provided to ensure the output pin turns on when the Control pin is floating. ■ Fault Detection Open Circuit Short Circuit Over Temperature ■ VCC Sense: Output Turns On with Loss of VCC ■ Low Standby Current Absolute Maximum Ratings Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65ûC to 150ûC VCC, Fault , Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to 6V ESD Capability (Human Body Model). . . . . . . . . . . . . . . . . . . . . . . . . . . 2kV Peak Transient Voltage (output off mode, output pin only) (26V load Dump @ 14V VBAT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40V Lead Temperature Soldering Reflow (SMD styles only) . . . . 60 sec. max above 183¡C, 230¡C peak Block Diagram VCC ISOURCE VCC(SENSE) Output Drive & Bias Package Options Control Overtemp Shutdown 8 Lead SO (internally fused leads) Duty cycle during short circuit Output VCC + - Fault + Gnd Gnd Gnd Gnd Gnd 1 Gnd Fault Control short circuit detect Gnd open circuit detect Gnd Cherry Semiconductor Corporation 2000 South County Trail, East Greenwich, RI 02818 Tel: (401)885-3600 Fax: (401)885-5786 Email: [email protected] Web Site: www.cherry-semi.com Rev. 12/28/98 1 A ¨ Company CS1108 Electrical Characteristics: 4.75V ² VCC ² 5.25V, -40¡C ² TA ² 85¡C; -40¡ ² TJ ² 150¡C PARAMETER TYP MAX UNIT Output ON Output OFF 3 100 6 250 mA µA Saturation Voltage VBAT =14V I OUTPUT = 350mA I OUTPUT = 180mA 16 1.1 0.9 100 1.5 1.3 µA V V VOUTPUT (self-bias) VCC < 4.5V, I OUTPUT < 200mA 3.5 V 650 60 mA mA 0.8 40 V V µA µA 0.40 V ■ Supply Requirements VCC Quiescent Current VCC Quiescent Current ■ Output Leakage Current ■ Current Sense Short Circuit Current Open Circuit Current ■ Control - Input Input Voltage Input Current TEST CONDITIONS MIN 350 20 Output in the ON state Logic = High Logic = Low Logic = VCC Logic = 0V 500 40 2.0 20 -20 -50 ■ Fault Output - (Open Collector) Output Low Voltage I FAULT = 250µA (sink) ■ Overtemperature Shutdown TJ Output Disable Threshold TJ Hysteresis 0.24 (guaranteed by design) (guaranteed by design) 150 5 180 ûC ûC Note: A fault signal will be shown (at the fault pin) during inrush as the short circuit threshold is exceeded. Package Pin Description PACKAGE PIN # PIN SYMBOL FUNCTION 8 Lead SO Narrow 1 Output 2 VCC 3 Fault Open collector output. 5V regulated supply input. 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. 2 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 Fault pin reports short circuit, open circuit, and overtemperature conditions on the IC. If a fault is present, the open collector output Fault 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 current will exceed the current limit threshold during the initial 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 condition 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 shutoff the output and the lamp will turn off. Once the die temperature lowers below the thermal threshold then the output will be allowed to turn back on. Applications Diagram Output CS1108 10nF VCC Gnd Fault Gnd Control Gnd 20k VBAT Gnd VCC microprocessor 3 CS1108 Circuit Description CS1108 Package Specification PACKAGE DIMENSIONS IN mm (INCHES) PACKAGE THERMAL DATA D Lead Count 8 Lead SO Narrow Metric Max Min 5.00 4.80 Thermal Data English Max Min .197 .189 RQJC RQJA typ typ 8 Lead SO Narrow (internally fused leads) 25 110 ûC/W ûC/W 8 Lead SO Narrow; 150 mil wide 4.00 (.157) 3.80 (.150) 6.20 (.244) 5.80 (.228) 0.51 (.020) 0.33 (.013) 1.27 (.050) BSC 1.75 (.069) MAX 1.57 (.062) 1.37 (.054) 1.27 (.050) 0.40 (.016) 0.25 (.010) 0.19 (.008) D 0.25 (0.10) 0.10 (.004) REF: JEDEC MS-012 Ordering Information Part Number CS1108EDF8 CS1108EDFR8 Rev. 12/28/98 Description 8 Lead SO Narrow (internally fused leads) 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. 4 © 1999 Cherry Semiconductor Corporation