TPS2490 - Undesired Responses
I'm using two TPS2490s independently to protect two separate resistive loads (175Ohms) from being operated in over voltage (30V), over current (10A) and over power (300W) states.
Both TPS2490s are wired similarly in the typical configuration without the dv/dt circuitry and drive a STF18NM80 as the external FET but both circuits are responding differently.
Hotswap (A) - With 2.4VDC applied to the enable pin, 28VDC applied to VCC, 4.7VDC seen on Vref, 3.5VDC on Prog and 32VDC being applied to gate pin of ext FET . Across the resistive load I'm reading 27VDC and across the external FET Vds I'm reading the voltage drop grow from 0.25V up to and setting around 1VDC. I would like see the full 28VDC across the load and get some insight into why Vref is over 4V. .
Hotswap (B) - With 2.4VDC applied to the enable pin, 28VDC applied to VCC, 4VDC seen on Vref and 3VDC on Prog, the PG pin remain low and 12VDC is applied to gate pin of ext FET when No load is attached. Attaching the load to the output causing the hotswap to reset and no longer drives a voltage out the FETs gate. I would like to know if there is any troubleshooting recommendation to get the Hotswaps to function properly.
I welcome any suggestion
-Chris
