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[FAQ] LP8860-Q1: Combined Output Operation and Diagnostics

Part Number: LP8860-Q1

Hello,

Background:

LP8860-Q1 is operated with all outputs (OUT1 - OUT4) shorted together to maximize LED current up to 600 mA. 8 LEDs are operated in series with Vf between 2.75V and 3.5V for each LED.

Questions:

1) What are the EEPROM parameters for this configuration ? LED_STRING_CONF[2:0] -> 110 or 101 ?

2) Will fault detection of Shorts & Open still work ? Is there additional configuration necessary ?

3)The boost adaptation and protection is explained in Figure 29 of datahsheet. With all outputs on same voltage level, will comparator levels work properly ?

4) Is it possible to detect the short / Open of a single LED ?

Best Regards

Martin

  • Answers:

    1.
    It can work, but we need to setup the EERPOM of below register to 101.
    2.
    The comparator level will work properly.
    3.
    See 1)
    4.
    Yes, if there is only single LED string.
    But if there is multiple string tied together as one string, the LED open can’t be detected.