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.
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.
I think R205 should be 10k for 5V output. Should be a typo?
For SCP recovery, I think the oscilloscope scale should be longer (~40ms/div). This can bee seen in the datasheet plots.
I have the same problem, the IC freeze to 2,5 V and no way to exit of this situation.
Using the same value of the EVB the load regulation is very bad, and with input voltage over 16V the chip freeze to 2,5V.
The output current is 30mA at 5V.
Using feedback value of 120K and 10K without forward capacitor the IC work well, if the input voltage rise-up slowly (2s), but with a direct power-on of 24V freeze again.
In this situation I attached a 300mA load, and the regulation work, but is inacceptable the freezing situation to 2,5V.
I do have exactly the same problem with the MP9486A. I believe during startup it enters SCP mode and does not recover. Is there a solution to this problem?
To all people that might have some instability problems with this chip, I have built a project using this MP9486 chip and applied some modifications. it works stable and flawlessly. Just follow my design and PCB and embed this board on your mainboard PCB
Hello Hesam, nice project and video . However I don’t like the R2 in your circuit. It seems more of a workaround . I selected the MP9486 for a new design, but sadly, after reading all these problems I tend to find an alternative. Your demonstration would have been reassuring, if it wasn’t for that R2.
Maybe you can provide some more details on this situation and the behaviour of the MP9486 WITHOUT the R2? Thanks.
