DRV8243-Q1: DRV8243 can't restart after Vvmuv is removed

And it can work after power supply again.

Hale,

Hale Tan said:

And it can work after power supply again

What do you mean by this statement?  It seems to contradict what you said before that device did not work when VM went back to working level.  

Please explain more so we can better help.

Regards,

Ryan

“device did not work when VM went back to working level” means that device did not work when the VM from 4V to normal voltage.

"it can work after power supply again" means that it can work when the VM power off and power on again.

Hi Hale,

Thank you for your question.

When VM goes down under 4V and go under VM_POR, DRV will go to reset state. Even if VM comes back, CLR_FLT is required to wake up. I guess this info helps. 

regards

Shinya Morita

Hi Shinya,

Thanks for your reply. Got it.

"They found that the VMUV is 0b, not 1b. I guess the  DRV8243S Variant's reaction fixed to retry setting. Is that true?" But why did the customer see the VMUV is 0 bit. The VMUV should be 1 bit to show that the device is in under voltage and we set CLR_FLT 1 bit to make it start. Is that right?

Thanks Shinya,

If the VM voltage is between  3.6V~4V, the VMUV should be 1 bit. Is that right?

Hi Shinya,

The customer replied that they need to refresh SPI_IN Register and set CLR_FLT 1 bit when the power supply goes up from 4V to normal voltage, then the device can work normally. Do we have similar phenomenon? 

Similarly, they found that when they tested device DRV8908 from sleep mode to operating mode, they need set operation control 1/2 register again and give nSLEEP high voltage level, then it can work normally. If not set operation control 1/2 register, the device has no output. Do you have any suggestion?

Hi Hale,

Thank you for your feedback.

If customer is using SPI_IN function, these register settings also will be reset. Since customer mentioned they need to set CLR_FLT 1, POR could happen and SPI_IN is also reset. I think this could make sense.

Customer need to re-program all register settings after VM get bellow 3.6V.

For DRV8908-Q1 question. Please generate new post since this is different device. If VM goes to POR level, customer need to program registers again.

If you have further questions, let's move to new post.

regards

Shinya Morita

Hi Shinya,

I think we might be confused. The customer need to refresh SPI_IN Register and set CLR_FLT 1 bit when the power supply goes up from 4V to normal voltage, then the device can work normally. And if they only set CLR_FLT 1 bit when the power supply goes up from 4V to normal voltage, then the device cannot work normally. The question is why we need to refresh SPI_IN Register. As the datasheet said, we only need to set CLR_FLT 1 bit. What's the reason?

As you said 'SPI_IN is unique register bit. In order to change from default value, first customer need to change "SPI_IN_LOCK" as unlock (10b)', the customer changed "SPI_IN_LOCK" as unlock when they tested. And do they need to lock the register after they finishing configuration?