DRV8306: When DIR is reflected to Gate Drive signal

Takashi Onawa

Part Number: DRV8306

Hi Team,

I have two questions regarding the timing when DIR is reflected to Gate Drive signal as following.

1. When changing the direction of rotation, how long does it take from changing the DIR input to being reflected in the gate drive output?

2. Is it ok to change the DIR logic during Twake at start up timing?
According to the datasheet, we need to take care about logic change timing at Twake for IDRIVE and VDS. So I want to double check just in case if we need to take care DIR as well in the timing.

"The hardware inputs (IDRIVE and VDS) are latched during the wake-up time (tWAKE). Any further change to these pins is ignored unless a power-up cycle or an ENABLE pin transition after sleep mode occurs."

Regards,

Takashi Onawa

over 5 years ago

0 Adam Sidelsky over 5 years ago

TI__Guru 65220 points

Onawa-San,

Thanks for posting on the MD forum!

Do you intend to change direction while the motor is spinning?
Yes DIR can be changed at any time.

Regards,

-Adam

0 Takashi Onawa over 5 years ago in reply to Adam Sidelsky

TI__Genius 13200 points

Hi Adam-san,

Thanks for your prompt response on this.

For you questions, I'm just asking that to the customer so please wait their replay.

Do you mean there are any issue if they switch the motor during spinning?

Regards,

Takashi Onawa

0 Adam Sidelsky over 5 years ago in reply to Takashi Onawa

TI__Guru 65220 points

Onawa-San,

If the motor is spinning then the energy in the motor needs to be controlled carefully. The energy rotating in one direction can cause a spike in the back EMF voltage or FET bus voltage if the direction is changed suddenly while the motor is spinning.

Regards,

-Adam

0 Takashi Onawa over 5 years ago in reply to Adam Sidelsky

TI__Genius 13200 points

Hi Adam-san,

Thanks for your prompt response on this.

OK, I understood and tell them that to the customer.

Could you also follow their question below? let me know if you have any data on the time.

>how long does it take from changing the DIR input to being reflected in the gate drive output?

Regards,

Takashi Onawa

0 Takashi Onawa over 5 years ago in reply to Takashi Onawa

TI__Genius 13200 points

Hi Adam-san,

Can I have any comments on my customers question above?
If you don't have the data, please tell me that.

Regards,

Takashi Onawa

0 Adam Sidelsky over 5 years ago in reply to Takashi Onawa

TI__Guru 65220 points

Takashi,

I do not have this data unfortunately.

Regards,

-Adam

0 Takashi Onawa over 5 years ago in reply to Adam Sidelsky

TI__Genius 13200 points

Hi Adam-san,

OK, I understood that you don't have the data.
But they at least need to check if it takes longer than 1ms or not. Could you check that to the designer?

Regads,

Takashi Onawa

0 Takashi Onawa over 5 years ago in reply to Takashi Onawa

TI__Genius 13200 points

Hi Adam-san,

If we do not complete this check early, we will lose this socket.
I need to do some escalation if necessary, but before I do that, could you comment on the current status of the confirmation?

Regards,

Takashi Onawa

0 Adam Sidelsky over 5 years ago in reply to Takashi Onawa

TI__Guru 65220 points

Onawa-San,

I will respond by end of business today.

Regards,

-Adam

0 Adam Sidelsky over 5 years ago in reply to Adam Sidelsky

TI__Guru 65220 points

Onawa-San,

The DIR pin change will be reflected within the 10-20uS range. I cannot confirm the exact value but it is much less than 1mS.

Regards,

-Adam

0 Takashi Onawa over 5 years ago in reply to Adam Sidelsky

TI__Genius 13200 points

Hi Adam-san,

Thanks. I understood. It's perfect.

Regards,

Takashi Onawa

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DRV8306: When DIR is reflected to Gate Drive signal