U479B

Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

The monolithic integrated bipolar circuit, U479B, is designed as a monitor for lamp failure in automobiles. The comparator threshold of U479B is matched to the PTC characteristic of incandescent lamps. The threshold is tied to V_4,6 = V_S - V_T where V_T = 8 mV.

If the voltage drop across the shunt resistor, Rsh, exceeds 8 mV, the output is turned off, otherwise, the output of U479B 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.