DRV11873: Start up current limit

na na78

Guru 16770 points

Part Number: DRV11873

Now we are testing a motor operation with DRV11873EVM.

However, we are facing problem the motor fails to start to spin sometimes.

The jumper setting is default except for J2/FS is uninstalled. And 12VDC power supply is connected.

Motor terminals are connected to COM, MOTA, MOTB and MOTC on the EVM respectively.

We obtained following waveform at motor start up. This capture indicates a waveform that motor can start to spin.

A phase current flows up to over 3A at motor start up but DRV11873 had been operational.

Is this current flow acceptable?

Do you think the cause of motor failing to spin is that the motor start up current could not meet DRV11873's spec?

BestRegards

over 6 years ago

0 Seil Oh over 6 years ago

TI__Intellectual 1555 points

Hey,

Motor current should not be factored into spin up failures.

Peak current of this device 2A hence I would recommend you to configure CS pin to bring supply current less than 2A.

If you still see the spin up failures. can you try with different FS setting? It will chage PWM frequency.

Thanks,

Seil

0 na na78 over 6 years ago in reply to Seil Oh

Guru 16770 points

Hi Seil

Thank you for your reply.

I changed Rcs but spin up failure is still happened.

I checked following application report.
www.tij.co.jp/.../slva778.pdf

I think our situation would be relative to it.

I have question about workaround procedure 2.2.

>> Target Motor Speed is Fixed Inside the False Detection Range of 101.6 Hz ±30%

It is not clear for me how to take this workaround. What is FGS intput?

BestRegards

0 Seil Oh over 6 years ago in reply to na na78

TI__Intellectual 1555 points

Nana,

Let us try this on the bench and get back to you.

Thanks,

Seil

0 na na78 over 6 years ago in reply to Seil Oh

Guru 16770 points

Hi Seil

Thank you for your cooperation.
I found another problem when I adjusted PWM duty.

Even if motor starts to spin without problem, when FG frequency reached 1KHz motor repeats start and spin.
Have you ever seen these case?

BestRegards

0 Seil Oh over 6 years ago in reply to na na78

TI__Intellectual 1555 points

Nana,

Yes it is an errata item.
www.ti.com/.../slva778.pdf

Thanks,
Sei

0 na na78 over 6 years ago in reply to Seil Oh

Guru 16770 points

Hi Seil

Thank you for your reply.

I understood that 1KHz would be met to errata item.
However, start up failure is still occurs .

And I could not understand what FGS is described as one of workaround.
The following is my first question.

>I have question about workaround procedure 2.2.
>It is not clear for me how to take this workaround. What is FGS intput?

Could you answer it?

BestRegards

0 na na78 over 6 years ago in reply to na na78

Guru 16770 points

Hi

I close this thread because I opened others with different tile.

Thank you for your support.

BestRegards

Motor drivers

Motor drivers forum

DRV11873: Start up current limit