TDA4VM: Power OK (POK) Test for Diagnostic implementation

Hi,

From the Manual RA829_TDA4VM_Safety_Manual_F5_draft_Auto:
For 6.3.405 Software Test of POK Monitor; We want to simulate undervoltage  and overvoltage conditions by adjusting monitoring thresholds. Our aim is to verify POK functionality.

I would like to test POK functionality to satisfy safety mechanism above. However, how to implement this feature is not clear to me. I followed POK programming model and implemented test for diagnostics like following:

1.all POKs  disabled by clearing POK_*_EN bits

2. set CTRLMMR_*_X_CTRL is set for POK_TRIM(0..127) and OVER_VOLT_DET values. X is OV or UV here.

3. set only desired POK bit + set POK_EN_SEL bit

Here I can verify Diagnostic functionality only for Overvoltage detection like as described below.

When I set POK_TRIM value to 127, and I read back POK_*_OV  status register as "Voltage good" (1).

When I set POK_TRIM value to 0,    and I read back POK_*_OV  status register as "Voltage above threshold" (0).

However, for UV Test for Diagnostic, POK_*_UV is always 0 after I tried POK_TRIM with values 0 to 127.

So I can simulate POK overvoltage error detection, but i cannot simulate undervoltage error detection. Because whatever value i give (0 or 127), UV error is always detected.

Any idea for this helps me very much.