DRV8701: Find a strange pulse pulse in SO pin in the DRV8701 EVM board

Eggsy Pang

Part Number: DRV8701

Hi team,

I test the SO waveform in the DRV8701 EVM board. There is a strange pulse pulse. But it work normally.

DO you know why?

Thanks!

0 Rick Duncan over 5 years ago

Hi Eggsy,

What load is connected across OUT1 and OUT2?

Does the load have a capacitor connected across OUT1 and OUT2?

Can you also provide the voltages on the SP, OUT1, and OUT2 pins on Channel 1?

This will help us determine the cause.

0 Eggsy Pang over 5 years ago in reply to Rick Duncan

Hi Rick,

There is not capacitor connected across OUT1 and OUT2. They connect BDC motor.

The voltages on the SP, OUT1, and OUT2 pins on Channel 1 in below pic.

0 Eggsy Pang over 5 years ago in reply to Rick Duncan

Hi Rick,

Any feedbacka and suggestions?

Thanks!

0 Rick Duncan over 5 years ago in reply to Eggsy Pang

Hi Eggsy,

Sorry for the delay.

Please see the image below. The SO pulse is consistent with the increase on SP.

The increase on SP appears to be ~40mV which translates to an increase of ~800mV on SO.

A capacitor on the SO output will slow the increase and lengthen the width.

Does the customer have a current probe to confirm the increase on SP is correct?

If this increase is correct, what is causing the increase?

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