MPM3515GQV is burning

[vsousa]

I’m facing a problem related to the MPM3515GQV voltage regulator. It is regulated at 5V.
When I supply the circuit with 20V or more, it burns out, short-circuiting. The load current is in the range of 600mA.
My PCB is a 4-layers with good heat-sink. What could I do to improve my circuit?

[Isabella.FAE]

Hi vsousa,

Thank you for posting to the MPS Forums! Is this issue only happening when the input voltage is greater than 20V? If that is the case, I would recommend increasing the resistor value on the EN/SYNC pin. The EN/SYNC pin requires a pull-up resistor that limits the current to that pin below 100uA. For an input of 20V, you would need a pull-up resistor greater than 135k. There is more information about this on page 13 of the datasheet.

Best,
Isabella

[vsousa]

Hi Isabella.
Thanks for answering me.
Very nice. I’ll do some tests.
Considering a wide input range, from 10V to 30V, I’ll use a 235k resistor to pull up the EN/Sync pin, following your tip. I think this is enough to turn on the device in 10V (14 uA), where EN/SYNC input current - IEN - would be 10 uA (max), from datasheet pg 4.
About a larger capacitance in the power supply, would that help?
Thank you.

[vsousa]

Unfortunately, increasing the resistance to 240k did not work and the MPM3515 keeps burning, however, I’ll use a 240k resistor as you suggested me.
I must add that the device works, but on some plug insertions it burns out.
So, I put a larger capacitance in the VIN (100 uF) and a 33V TVS to avoid unknown overvoltages.
The yellow trace is the VIN;
Cyan trace is the EN/SYNC;
Violet trace is the 5V output in a 1,3A load;
Green trace is the FB voltage.
Till now, the circuit is working. I’ll do more tests.

Thanks.

[Isabella.FAE]

Thank you for the update. Is the MPM3515 still only burning with supply voltages above 20V?

[vsousa]

Now it has stopped burning even with 32V in the input.

The circuit is like this:

The major contribution is the 100uF input capacitor. Without it, the device burns. And your suggestion about the 240k resistor.

I’ll do this to more circuits for testing and inform you.
Thank you.

[vsousa]

Hi Isabella.
I’ve made lots of tests and the MPM3515 stopped burning.
The major contributions are the 100uF input capacitor and your suggestion about the 240k resistor on the EN pin.
I clamped the input with a 30V Zener and the output with a 6V Zener.
Till now, this is my solution.

Thanks for your help.

[Isabella.FAE]

Thanks for the update, I’m glad that the burning has stopped. If you come across any other problems with the MPM3515, please reference this post and create a new one.