DRV8701: tOFF is not constant

Flemming Thomsen

Prodigy 10 points

Part Number: DRV8701

Hi, when I measure on the SO pin, I see the normal tOFF time of 25us, but sometimes it is shorter e.g. 10us.

The attached measurement shows the voltage on SO pin and the current in the coil.

What can cause tOFF to be shorter ?

Also note the spikes on the current. Is this normal?
I am using halve-bridge operation mode.

Regards Flemming

over 4 years ago

0 Pablo Armet over 4 years ago

TI__Mastermind 37683 points

Hi Flemming,

The current spikes are expected. When the output change states, there will be slight current spikes which are small enough so that it does not cause problems with the driver operation.

Can you take another waveform showing SNSOUT?

0 Flemming Thomsen over 4 years ago in reply to Pablo Armet

Prodigy 10 points

Hi Pablo

I have added SNOUT in channel 2.

0 Flemming Thomsen over 4 years ago in reply to Flemming Thomsen

Prodigy 10 points

Hi Pablo

Thank you for the explanation on the current spikes.

For the tOFF time not being constant, we found a bug in our software.

Regards Flemming

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DRV8701: tOFF is not constant