Buck regulator cutting off during short-circuit

[ARQuattr]

I have a buck regulator designed around the NCV8852 controller IC (https://www.onsemi.com/pub/Collateral/NCV8852-D.PDF), as shown in this schematic: **broken link removed**

The circuit works fine for moderate current levels and shuts down during short-circuit conditions as it is designed to, but the intended load is a very low resistance device (~1 Ohm). What I want to achieve is current limiting but not have the output shut off, i.e. I would like it to continuously deliver the limited current through a direct short at the output.

What's happening is that at some point after the current reaches the limit the device shuts down temporarily. The output voltage is not regulated since the feedback is set at a fixed value such to keep the output on, so the output voltage floats to about the input voltage. Therefore this shutdown shouldn't be caused by the undervoltage short-circuit protection.

I believe it's shutting down because of the 150% overcurrent protection threshold (Vocp). What I've found is that if I increase the gate resistor (R12) to around 10k, this stops happening, however then I get a lot of switching loss and the FET overheats.

I was thinking that I might control this by adding C2 (currently not populated) and changing R13, and/or working with R14 and C3. Honestly I just guessed at appropriate values for those and am not too familiar with how to design the compensator network.

Any suggestions on how to achieve sustained full output current during short-circuits would be much appreciated.

Thanks,
Angelo

 

[FvM]

Some points in the datasheet are suggesting, that the device ist not suited for the intended usage, e.g.:

When the output voltage falls below the short circuit trip voltage the part enters short circuit latch off.

 

[ARQuattr]

Some points in the datasheet are suggesting, that the device ist not suited for the intended usage, e.g.:

Thank you for your reply.

I agree, but I haven't been able to find something more suitable in this range of device. In particular it should be simple (low cost), and it needs to use a high side sense resistor. Any suggestions?