DRV8426E: Fast decay in ripple control mode

Kuramochi Tadahiko

Part Number: DRV8426E
Other Parts Discussed in Thread: DRV8426, ,

Hi,

Could you tell me the condition that decay mode turns fast decay on ripple control mode as the following inside of red rectangle?

I would like to know in the case of DRV8426E(PH/EN control interface).

Best Regards,

Kuramochi

over 4 years ago

0 Wang5577 over 4 years ago

TI__Guru 56650 points

Kuramochi-san,

DRV8426E senses the VREF pin voltage to change the setting current. I won't think the ripple control decay mode would give the fast decay.

If we have to generate the fast decay, we may need to follow the "DRV8426E (PH/EN) Control Interface" table to get the fast decay when the host controller decides to change the VREF.

Regards,

Wang Li

0 Kuramochi Tadahiko over 4 years ago in reply to Wang5577

Guru 28715 points

Hi Wang-san,

Does it mean that the inside of the above red rectangle is not fast decay?

A waveform like this tilt is observed on the also actual system.

Best Regards,

Kuramochi

0 Wang5577 over 4 years ago in reply to Kuramochi Tadahiko

TI__Guru 56650 points

Kuramochi,

Would you share your test waveform?

Thanks,

Wang

0 Wang5577 over 4 years ago in reply to Wang5577

TI__Guru 56650 points

Kuramochi,

I just verify it on an DRV8426EEVM. When the VREF steps down, we can see the ripple control decay mode gives the fast decay.

Regards,

Wang Li

0 Kuramochi Tadahiko over 4 years ago in reply to Wang5577

Guru 28715 points

Hi Wahg-san,

Thank you for your information.

How much is the VREF step-down size to get the fast decay?

I would like to know the threshold voltage.

Best Regards,

Kuramochi

+1 Wang5577 over 4 years ago in reply to Kuramochi Tadahiko

TI__Guru 56650 points

Kuramochi,

On my test, when the VREF step down was bigger than 150mV, I saw the fast decay during the transition.

Regards,

Wang

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DRV8426E: Fast decay in ripple control mode