U479B

Features 2-kV ESD Protection Two Comparators with Common Reference Tight Threshold Tolerance Threshold Matched to PTC Characteristic of Incandescent Lamps Temperature Compensated NPN Output Interference and Damage-protection According to VDE 0839 EMI Protection Reversal Polarity Protection Load-dump Protection Automotive Lamp-outage Monitor IC U479B Description The monolithic integrated bipolar circuit, U479B, is designed as a monitor for lamp failure in automobiles. The comparator threshold is matched to the PTC characteristic of incandescent lamps. The threshold is tied to V4,6 = VS - VT where VT = 8 mV. If the voltage drop across the shunt resistor, Rsh, exceeds 8 mV, the output is turned off, otherwise, the output is turned on. Without supply voltage or open input pin 8, the output is turned off. A comparator input, which is not used, must be connected to pin 7. Figure 1. Schematic and Application Circuit VS 2 Rsh Z2 + 0.6 VS + 8 + 6 1 Lamps R1 3 & & VBatt 7 5 OUT1 4 Rsh OUT2 150 Ω Rev. 4775A–AUTO–11/03 Pin Configuration Figure 2. Pinning DIP8/SO8 1 2 3 4 8 INPUT VREF IN2 OUT1 GND VS OUT2 7 6 5 1N1 Pin Description Pin 1 2 3 4 5 6 7 8 Symbol GND VS OUT2 IN1 OUT1 IN2 VREF INPUT Function Reference point, ground Supply voltage Output 2 Input 1 Output 1 Input 2 Reference voltage Input switch 2 U479B 4775A–AUTO–11/03 U479B Absolute Maximum Ratings Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the...