LM74910-Q1: Chip damage with reverse -12V input

Hi Charles,

How did Lenovo confirm if the chip is damaged?

Can they probe A,C,DGATE,OUT during -12V test.

Regards,

Shiven Dhir

Hi Dhir,

1. -12V input condition the LM74910 is hot;
2. recover the 12V input, the LM74910 don’t work in the normal mode;
3. -12V input, check the MOS Vgs voltage, the MOS could turn on, so it means the negative voltage on the IC pins.
4. the LM74910 picture as below:
5. 

Waveform can be seen below:

Test condition:

The board 12V input connect to the DC source GND,  and the board GND connect to the DC source +12V;

And the Oscilloscope GND connect to the DC source GND.

Charles