If the high-side switch shuts down unexpectedly, all DC/DC converters that supply LED drivers, MCU, FPD-link and others also shut down. This can trigger VDD undervoltage protection in LED driver IC LP8866(S)-Q1 as DC/DC supplying VDD shuts down even though the LED driver supports low voltage condition. If the VDD falls below VDDUVLO falling level during device operation, IC stops switching and LED outputs are turned off, and the device enters STANDBY mode. The VDDUVLO_STATUS fault bit is set in the SUPPLY_FAULT_STATUS register, and the INT pin is triggered. The LP8866S-Q1 restarts automatically to ACTIVE mode when VDD rises above VDDUVLO rising threshold.

In Figure 2-1 and Figure 2-2, LED drivers shut down because of a VDD UVLO fault. This resets the IC causing a POR (Power on Reset). Therefore, if the system is not stable under cranking condition which leads to the VDD drop, the LED driver does not light up as the expected scenario. If the system is not written, run the I2C command again. This risk can also make software design more complicated.