DRV8308: Restarting from a momentary power failure

tatsuro tokugawa

Part Number: DRV8308

Hi team,

When a "1 second" momentary power failure occurs during motor rotation, then just after that(1sec later) I try to set the registers again via SPI to restart the motor.
However, register setting is not possible. (The registers remain its initial value)

I think "5 second" momentary power failure is okay for the register setting via SPI.
(The values set in the registers are reflected)

Could you tell me what is the possible cause?

Best Regards,
Tatsuro

over 2 years ago

0 Aaron Barrera over 2 years ago

TI__Mastermind 26046 points

Hi Tatsuro,

Can you check contents of this post?

https://e2e.ti.com/support/motor-drivers-group/motor-drivers/f/motor-drivers-forum/941559/drv8308-drv8308

Monitoring VREG could be helpful since it powers the SPI block.

Thanks,
Aaron

0 tatsuro tokugawa over 2 years ago in reply to Aaron Barrera

Prodigy 100 points

Hi Aaron-san,

Thank you for your reply.

> Can you check contents of this post?
> e2e.ti.com/.../drv8308-drv8308

The setting of the registers before the momentary power stop is as follows.
ENPOL(0x00[11])=0
VREG_EN(0x0A[10])=0

The reason why I can not set the registers I assume is as follows.
1. The momentary power stop occurs.
2. VM voltage drops and logic is reseted as shown in "data sheet 7.3.3".
3. Power is turned on again, but this device is in the "stop-and-power-down sequence" shown in data "sheet 8.3.1" because the motor is coasting and spinning.
4. If I try to set the registers via SPI, this device will not accept the register setting because it is in a stop-and-power-down sequence.

Is my understanding correct?

Best Regards,
Tatsuro

+1 Aaron Barrera over 2 years ago in reply to tatsuro tokugawa

TI__Mastermind 26046 points

Hi Tatsuro-san,

This looks correct. The stop-and-power down sequence of 1s may not allow SPI writes/reads until it is complete.

Thanks,
Aaron

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DRV8308: Restarting from a momentary power failure