MP6540A: Over-Current Protection (OCP)

Motor Drivers/Sensors
1

Hello,
we are using MP6540A to drive a 24V/30W BLDC. When testing OCP by connecting a wire between output SA and SB, the Low Side Mosfet of output SA got permanent shorted (destroyed).
As by chip design, the driver should be fully protected against short circuits in all directions.

Any ideas what went wrong?
Do we need a special control-sequence when a short-circuit occours to avoid damaging of the driver-chip?

Best regards

Frank

2

HI @frank.mammen,

Thanks for reaching out on the technical forum. Sorry to hear the part was damaged when you shorted two of the outputs together. You should not need to follow a special control sequence when a short circuit occurs.

What is your input voltage set at?

3

Hi Stephen,
Thanks for your answer. It looks like that the Mosfet got a thermal damage because our controller did not shut down the drive.
Input voltage is set to 24V (regulated).

But we are got into another problem. When we shut down the supply voltage by a mechanical switch (vibrating contacts) it happens from time to time the MP6540 won’t restart. We must switch of the 24V-Supply voltage for a certain time to get the chip operating again.

4

Hi Frank,

thanks for following up. Interesting the part won’t come back up. In order to help debugging can you share your layout and schematic as well as the expected input, output, and load requirements?

5

Hi Stephen,

Part of Schematic:

Power section of the BLDC-Drive
Power section of the BLDC-Drive695×477 70.9 KB

Caused by this error message:
"An error occurred: Sorry, new users can only put one embedded media item in a post.
I can only publish the schematic.

If you need more information, let me know.

Best regards

Frank