I am using the LM7372 to drive a piezoceramic stack. The stack is in parallel with an inductor so there is no way the stack can build up charge. However, we are seeing a significant number of failures of this chip. I suspect it is a latch up effect but I am no familiar with diagnosing this failure. The LM7372 is not powered most of the time. It is switch off form the 15 volt batter by an FET. Also, most of the time the battery is disconnected from the circuitry. I did a simple ohm meter investigation of two failed chips and one new one. Here at the resistance value with respect to V- pin 4.
Pin# Name Failure 1 Failure 2 New Chip
1 Out A 2.24K 132 ohms 20Meg
2 -INA 4.7meg 1.1K 47meg
3 +INA 520 ohms 4.8meg 17meg
5 +INB 2.7K 4.8meg 19meg
6 -INB 570 ohms 4.8meg 46meg
7 Out B 82 ohms 150 ohms 17Meg
8 V+ 467ohms 111 ohms 34 meg
I suspect the failure could be latch up but not sure. Please help. I would really like to talk to someone on the phone or in Windows Teams. It would make the transfer of information much Quicker.
Thanks Don Kyle
972-418-3057
