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UCC5880-Q1: fault related behavior check

Chuqiang Wen
Expert 4830 points
Part Number: UCC5880-Q1

Tool/software:

Hi Expert, 

My customer is evaluating UCC5880-Q1. Some questions need your support. 

1. Regarding to the nFLT1 and nFLT2 behavior, Table 7-3 in datasheet shows the fault condition and corresponding recovery operation. But I still not clear for the nFLT1 behavior if the fault is removed. After the fault(like VCC2 UVLO fault) is removed, does the nFLT behavior will be latched until fault bit is cleared? Or the nFLT will be recovered to high level once the fault is removed? 

2. For the VCC2 OVLO fault, customer feedbacked that they cannot get the same phenomenon mentioned in datasheet. You can find their test description as below. May you kindly check the reason? 

Set CFG2[OVLO2_TH]=00b, ACT1[OVLO2_ACT]=11b, -> modified the R73 resistor to 81K(18.9V on VCC2) -> read FAULT2[OVLO2_FAULT]=0b and OUTL not be pulled low. 

They also tried to increase the VCC2 voltage to 22V, but the behavior still not as expected. They can get VCC2 OV fault in fault register several times with tried many times. 

Register value: 

 

UCC5880 device marking: 

Thanks!

Ethan Wen

  • 0
    TI__Expert 3665 points

    Hi Ethan,

    1. The fault will be latched until the CLR_FAULT command is sent.

    2. Can you please provide more details on what is happening. It looks like the UVLO2 is set to 18V, but the OVLO2 is not reporting. However in the end, you said "They can get vVCC2 OV Fault". Was that a typo? It looks like the fault isn't reporting. What is the R73 resistor. Can you share the schematic?

    Regards,

    Akshat

  • 0 in reply to Akshat Murali
    Prodigy 10 points

    Hi Akshat

    Please refer to the following schematic, I test this issue by using TI UCC5880Q1 EVM.

    When supply VCC2=18.9V, Set CFG2[OVLO2_TH]=00b, ACT1[OVLO2_ACT]=11b, no faults were reported.

    Even supply VCC2=22V, no faults found.

  • 0 in reply to li xuyang
    TI__Expert 3665 points

    Hi Ethan,

    Okay I understand better now. Thank you. So the configuration you have done is correct. If the VCC2 voltage is >18V, the device should report a fault and pull the output low. 

    Are you configuring the OVLO2 thresholds on both the high side and low side GUI windows? Are you probing at TP15 - TP17? It looks like you are performing the test on the low side driver. Can you confirm if the GUI is using the low side driver and not the high side driver. 

    If this doesn't work, can you apply the 22V directly to the VCC2 TP15 and check?

    Regards,

    Akshat