Folks,
We have designed a control board for our motor controller using LM5106 for driving the MOSFETs on the power board. We have been using this for the past couple of months. Had one issue before which was resolved using this forum.
Now we are seeing a strange thing since morning. The driver ICs are failing rather mysteriously one after the other. We have isolated the control board for our testing. For testing we are toggling the ports at 1 KHz. The failure mode is as follows
1. The low side driver is working OK. The output port is toggling at 1 KHz
2. High side output is stuck at high as measured between pins 3 and 4, between HO and HS. We are using a isolated power supply instead of a bootstrap capacitor mostly because we have weird duty cycle requirements for driving the mosfet.
Initially there was one driver which was bad and all the others were working OK. We thought maybe it was static or some other random stuff. But after that, before replacing the failed part, we powered the board again to retest and we had an additional failure and so on and on. We now have 5 failed out of 12. We do have a 22K resistor from the output to the respective ground. When I check the resistance of the output wrt to ground we do read 22K on all the output ports, This board was working fine before. Kind of crazy situation for us. Appreciate any pointers.
Thanks. -Bhaktha