SNVA966 July 2020 – MONTH LP8864-Q1 , LP8864S-Q1 , LP8866-Q1 , LP8866S-Q1
During power line FET pre-charge state, each active LED output pins outputs a typical 6-mA current for 300-µs period. The LED output pin is recognized as short to GND if its voltage is lower than VHEADROOM in this time period. LED short to GND fault will be reported.
During boost soft start and normal boost operation, if LED output is lower than VSHORTGND for 20 ms, device turns off the corresponding LED output channel and output a typical 6-mA current for 300-µs period again. After this operation, if output voltage is still lower than VHEADROOM, LED short to GND fault will be reported.
If LED short to GND is reported, boost, LED outputs and power-line FET is turned off, the device will enter STANDBY mode. LED_STATUS bit is set and an interrupt generated similarly as in open LED case. LED short to GND fault reason can be read from bits LED_GND and LEDx_FAULT (x = 1...4 (LP8864-Q1 & LP8864S-Q1)/ 6 (LP8866-Q1 & LP8866S-Q1)), indicating the faulty LED) in LED_FAULT_STATUS register. These bits maintain their value until device powers are down while the LED_STATUS bit is cleared by the interrupt clearing procedure.