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UCC2897A: How to detect a fault

Tobias Ubostad
Prodigy 30 points
Part Number: UCC2897A


Tool/software:

Hello,

We are trying to determine how to best detect if UCC2897A is in a ''fault-mode'', i.e. either triggered by LINEOV, LINEUV, CS or any of other events that can trigger a fault on the IC. 

The aim of fault detection is to use the signal to disable a LDO that is supplied from the VDD/PVDD. 

Thus, we are wondering if the SS-pin can be used to determine if there is a fault? If so, at which voltage should be program the LDO disable? 

How far does the SS-pin voltage have to fall until UCC2897A stops switching? In the datasheet it is mentioned that the shutdown voltage of SS is 0.5V (typ.), and that its functional range is between 2.5V and 5V (and I assumed that the AUX- and OUT-pins are switching in this range). Thus, I would assume that below 2.5V would be a good point to disable the LDO. For instance at 2V. Is my understanding correct? 

Best regards,

Tobias

  • +1
    TI__Guru 74115 points

    Hi,

    SS reaches >= 2.5V switching starts, SS reaches <2.5V switching stops. LINE UV and OV will affect SS and cause it discharge, CS has to reach > 0.75V with in 50ns from 0 to 0.75V to cause SS discharge.