DRV3946-Q1: NAD_Error detection

Thanks Ibinu.

Ibinu,

Customer feedback that DRV3946 report NAD_ERR in Init 2. They find the PVDD is UV status when error happens. They need TI help confirm whether NAD_ERR will appear in INIT2 when PVDD is UV & VDD is 5V?

Note: They didn't receive VDD_ERR when PVDD is UV.

Hello Beida,

The device will not start the INIT2 if PVDD UV condition exists. Please see the startup sequence in datasheet.

If the PVDD UV is happening, then we would expect a VDD_ERR. This can be distinguished from NAD-ERR with the B23 in the frame.

Can you take a look at the SDO waveforms and see what exactly is coming?

Thanks,

ibinu

Hi  Ibinu,

There is a scenario: The PVDD is normal in Init 1. When detection go into init2, PVDD is UV. The device will go back into to Init1? What error will device report?

Form customer's feedback, the identify NAD_ERR by SDO communication waveform.

Ibinu,

New question: After DRV3946-Q1 goes into active state, they try to power down PVDD and reserve VDD. In this condition, they need to turn off relay. So they operate as below:

1. Customer send CMD1(CLR_FAULT=1 & CH1_CTRL=0) and read CH1_STAT is still 0x5.

2. Wait several seconds, they try again to send CMD1(CLR_FAULT=1 & CH1_CTRL=0) and read CH1_STAT is 0x0.

For two operation, PVDD is always UV. Customer wants to know whether there is internal delay after PVDD_UV so that the CH1_STAT can't change? Or whether they need to send CLR_FAULT=1, then send CH1_CTRL=0 to change CH1_STAT, not send two command together?

Hi Beida,

Is the PVDD back before doing this?

In case the PVDD is still low then the UV warnings will be shown.

Thanks,

Ibinu

Ibinu,

Customer's question is that CLR_FAULT doesn't work well after PVDD_UV. Afer several seconds, resend CLR_FAULT command, it works. But the PVDD is still UV state. Why?