MP9486AGN locks up

Hello,

I am in the final stage of replacing our current DCDC converter by MP9486AGN-Z.
we have an input range of 7-60V (nominal 24V) and an output current of max. 1A @ 5V.

I ordered some samples and assembled a test circuit on a breadboard pcb.

R204 = 24k, R205 = 1k

The converter works up to 800mA (no problem - I expect thermal issues on the breadboard pcb)

however. when I make load jumps or short circuit on the output, the DCDC converter does not recover to 5V. It “locks up” at around 2.5V and (around 100mV at the FB pin) and it does not supply much current in this state.

I was only able to resolve this issue by disconnecting and connecting the external voltage. (and also by shorting the FB pin to GND very shortly - of course resulting in an overshoot of the output voltage - I was just curious if this would resolve the issue)

I also replaced the Chip with a new one - same behaviour.

Any ideas what could cause this issue / how to resolve it? The value of C209 seems to influence the behaviour in case of load jumps. But a lock up after a short circuit is not acceptable for the application.

Thanks and BR
Oliver

Hi Oliver,
Thank you for the question.
I will get back to you shortly on this.

Regards,
Yash Shah