The MP3391 BOSC pin shows a normal sawtooth waveform of 6.5kHz. VCC and VDD measure 4.8 V and 9.8 V, respectively, but the FF pin stays low. The IC is configured for 8-channel operation (NUMSEL floating), with LEDs connected to only one channel. According to the datasheet, the LEDs should still light. However, the LEDs flash once and then turn off. The IC subsequently enters fault mode, and no switching signal is observed at the gate output.
Hi,
So sorry for the late response. Can you clarify whether you are using our EVB to do the test or you are testing on your own PCB? If you are testing on your PCB, can you share the schematic?
Also, what is your input voltage, what is the part number for the LED?
My initial guess is that might be a problem of the schematic. After you give me more information, I can help you debug. Thanks.
Best,
Fox