Tool/software:
Hello everyone, I'm using the TPS2492PW hot swap controller in a DC Link circuit. The Rsense resistor has a value of 2.5 mΩ, a power rating of 3 W, and a temperature coefficient of 75 ppm/°C. According to the datasheet, the device should trigger an overcurrent shutdown at around 20 A, but in practice, I’m seeing shutdowns occur prematurely at approximately 16 A. Moreover, the shutdown is not immediate—it happens after several minutes of operation.
The voltage across the sense resistor at the time of shutdown is around 40 mV, which is below the expected threshold for overcurrent protection. The circuit parameters are as follows:
- Supply voltage (max): 30 V
- Load current (max): 20 A
- Ambient temperature (max): 55 °C
- MOSFET used: FDB86135
In SPICE simulations, the circuit behaves as expected, with no early shutdowns.
I’m trying to determine the root cause of this behavior. The datasheet doesn’t mention any built-in thermal protection in the TPS2492PW, but could thermal effects—such as resistor drift or MOSFET heating—be contributing to the issue? Has anyone encountered similar behavior or have suggestions for further diagnostics?
Below is a snippet of schematic for reference and some photos:
Voltage across shunt, shows that controller turns off fet after cca. 2 min
Voltage drop on shunt.
Any insights or recommendations would be greatly appreciated. Thanks in advance!