I am struggling with reproducing a correct layout for the MPM3630.
Output Voltage: 6 V (R3 is actually 5.62 kOhm)
The issue is, that it is working fine at first but when I try disconnecting and reconnecting the Battery voltage multiple times, then after a couple of times the circuit burns at the VIN pin.
I am relatively sure that the internal MOSFET power stage gets too hot.
There is no load connected.
I tried the same experiment with the EVM3630-QV-00A evaluation board: It works fine.
The higher input capacitance (40 µF) in my circuit does not seem to be the issue.
If I increase the input capacitance on the eval board, then it still works fine.
Therefore I am sure that I have a big mistake in my PCB layout, but could not find it up to now.
Does anyone have a hint as to what might be the error here?
The ringing on the VCC line seems to be a logical explanation.
Somehow the eval-board layout seems to supress the ringing better than my layout does.
I suppose that the big VCC and GND areas might work as an additional parasitic capacitor which suppresses ringing.
Other hints or explanations are highly appreciated.
Other than that I will limit VCC to a 3S LiPo and consider the issue as solved.
You have inrush current issue which results in transient during battery connection. Just to prove it, add 0R5 resistor in series with input, quite sure you won’t be able to burn it again.
Solutions: soft start circuit, TVS, electrolytic or polymer capacitor or even resistor if you can afford some power losses.
