ZHCU741 July 2020
This reference design is a self-contained LED headlight driver. Three power inputs, Lowbeam, Turn Indicator and Daytime Running Light/Position Marker Light are reverse battery protected. A fourth reverse battery protected signal input, Highbeam, determines whether to shunt or open via a MOSFET the Highbeam portion of the Highbeam/Lowbeam LED string. Daytime Running Light/Position Market light, as setup for testing, is always powered. Daytime Running Light/Position Marker Light function is determined by the other two power inputs Lowbeam and Turn Indicator. The test board is one of many possible configurations. A table shows light function based on inputs as configured for functional testing:
INPUT | INPUT | INPUT | OUTPUT | OUTPUT | OUTPUT | OUTPUT |
---|---|---|---|---|---|---|
Lowbeam | Highbeam | Turn Indicator | Lowbeam | Highbeam | Turn Indicator | DRL/POS |
0 | 0 | 0 | off | off | off | high |
0 | 0 | 1.5 Hz | off | off | 1.5 Hz | 1.5 Hz |
0 | 1 | 0 | off | off | off | high |
0 | 1 | 1.5 Hz | off | off | 1.5 Hz | 1.5 Hz |
1 | 0 | 0 | on | off | off | high |
1 | 0 | 1.5 Hz | on | on | 1.5 Haz | 1.5 Hz |
1 | 1 | 0 | on | off | off | high |
1 | 1 | 1.5 Hz | on | off | 1.5 Hz | 1.5 Hz |