Part Number: TPS2663
Hi,
We are using the TPS2663 as protection on a 5V power rail in a new design.
We are using the reverse protection FETs on the input to the device.
Simulation in PSpice shows good performance.
We now have boards in house and we noticed a relatively large voltage drop (0.5V) across our input FET (STN3NF06L). IN_SYS is 5V, driven from a bench PSU. nSHDN is high (3.3V). The BGATE pin is only being driven to 5.5V, which is not sufficient to fully turn on the STN3NF06L.
The TPS itself appears to be otherwise functioning correctly, and we are able to pull current from the OUT rail, but because we're dropping a lot of voltage over the input FET, the output voltage is insufficient for PGOOD to go high, and to drive the load we need to drive.
Could you please advise as to why BGATE would only drive to 5.5V. The datasheet suggests it should be driven to 10.2V above IN_SYS, but we are only seeing 5.5V at the pin.
On the same board we have the same setup for a 24V rail (though with different thresholds and ILIM values), and this also appears to only drive BGATE to 0.5V above IN_SYS (24.5V). I would expect 10.2V above IN_SYS (34.2V) from the datasheet. We are also dropping 0.5V across that FET (OUT voltage is 23.5V).
Someone else on the forum appears to have had the same issue, but it was never resolved (the designer just removed the reverse protection FETs, but this is not an option for us).
Thank you
