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Original question:

TPS61378-Q1: place of manufacture

TPS53319: OVP behavior

Denny Huang
Expert 7170 points
Part Number: TPS53319

Dear team

The customer would like to  confirm the OVP function.

On Forced CCM mode, what is the action of the internal switching MOSFET when VFB>0.6*120%?

(1) The high side MOSFET is turned off, and the low side MOSFET is fully turned on?

(2) The high side MOSFET is turned off, and the low side MOSFET is turned on for the minimum duty cycle?

(3) Both high side MOSFET and low side MOSFET are turned off? The above troubles you to take the time to reply, thank you

Could you help to recommend.

Many thanks

Denny

  • 0
    TI__Genius 11315 points

    Hey Denny,

    Please inform the customer to reference Section 8.3.8 and 8.3.9 of the TPS53319 datasheet. The actions of the MOSFETs are described based on whether the ROVP pin is enabled or not.

    Thanks,
    Caleb 

  • 0 in reply to Caleb Perez
    TI__Expert 7170 points

    Hi Caleb

    The figure below is TPS53319EVM user guide(SLVU72) OVP test waveform.
    1. The B-C interval is OVP operation, such as the internal low side MOSFET turn-on, why does the output voltage not drop significantly?
    2. Can you provide the LL voltage and current test waveforms during OVP?

    Many thanks

    Denny

  • 0 in reply to Denny Huang
    TI__Genius 16495 points

    the converter is configured for auto skip and there is no load/very light load prior to the fb pin fault (no LL switching). 

    The low side fet is connected to the output through an inductor. 

    The current through an inductor can not instantaneously change, the current must ramp. 

     The low side fet has a sinking current limit.   Once the low side current limit is reached, the low side fet will turn off.

    The output voltage discharges in ~40us.    If the output was loaded the output will discharge more quickly.

    Since there is no load, inductor is in series with ls fet and the low side fet has a current limit the output capacitor will take time discharge. 

    Adding load, using lower inductor value and output capacitance will allow a faster discharge