Hi there,
I'm working on a current sensing application using the INA302A1 for electronic fusing in a robot power supply. Basically I'd like to set current threshold limits for a "slow blow" and "fast blow" fuse using the ALERT2 and ALERT1 outputs respectively. Both pins are tied together in a wired OR configuration with a shared pull-up resistor for an active low FLT signal which is then fed into control logic for a power MOSFET.
I tested the INA302 chip using the EVM and it seemed like it should work great for this application. After assembling my own prototype board, however, I'm running into some issues. I seem to have burnt up a few INA302 chips and I'm not sure why. My common mode voltage is 24V and my shunt resistor is 10mOhm. As I adjust the current through the shunt resistor with a variable load I eventually end up with a short between 24V and GND. This is with currents <1A, so I don't think that I'm exceeding the maximum differential input voltage. I've checked the rest of my board and it's definitely related to the INA302. I've read the datasheet carefully and I followed the suggested board layout closely so I'm confused as to why I keep blowing up chips. About the only change that I made was connecting the two ALERT signals together in a wired OR configuration, but since they are open-collector outputs I didn't think that would cause a problem. My analog design skills are a bit rusty, so I would appreciate any insight you all might have.
Here's a portion of the schematic:
Thanks,
Domenic Rodriguez