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TPS26630-33EVM: TPS2663: Operation at voltage interruption

Part Number: TPS26630-33EVM

Hi TI Team.

Let me ask this question as a continuation of the above thread.
TPS2663: Operation at voltage interruption - Power management forum - Power management - TI E2E support forums

I purchased EVB and did an evaluation on the above.
The waveforms when a 10ms momentary power loss is performed are shown below.

Our product is connected to the Vout side of the EVB. The capacitive load is 7072uF.
The EVB is also modified as follows.
C4(Cdvdt)=2.2uF
C3(Cout)=NC
D4=NC
R2:=1MΩ, R3=51kΩ, R5=34kΩ (UVLO=15.3V, OVP=38.3V)
R12=NC, R13=NC, PGTH pin connected to GND


Question 1: 
I am assuming that the value of UVLO_ton(dly) will be as follows, is this correct?
UVLO_ton(dly)=742+49.5×2200(Cdvdt[nF])=109,642us(110ms)

Question 2: 
In the actual waveform, it took 416ms for the voltage to return.
Do you have any idea about this?

  • The system configuration of the product was changed and the Voltage Interrupption was measured when the capacitive load was Cout=1462uF.



    As with Cout=7072uF, the voltage rises when Vout drops to about 10V.
    I also changed the time width of the voltage interruption, but the fact that the voltage rises when Vout drops to about 10V did not change.
    What determines this "10V" value?

  • Hi Shotaro,

    I will get back by tomorrow EOD on this.

    Regards

    Kunal Goel

  • Hi Shotaro,

    Question 1: 
    I am assuming that the value of UVLO_ton(dly) will be as follows, is this correct?
    UVLO_ton(dly)=742+49.5×2200(Cdvdt[nF])=109,642us(110ms)

    Rakesh-> Your UVLO_ton(dly) calculation is correct.

    Question 2: 
    In the actual waveform, it took 416ms for the voltage to return.
    Do you have any idea about this?

    Rakesh-> The device is restarting in dvdt mode as you connected PGTH pin to GND.

    Please populate back R12 and R13 and test again.

     

    Regards,

    Rakesh

  • Hi Rakesh,
    Thanks for the reply.

    Question 2:
    I share the waveforms when R12 and R13 are populated.
    The constants except R12 and R13 are the same as #1.
    Also, PF of 3ch is a signal to confirm internal shutdown (Power Fall).
    R12:499kΩ
    R13:56kΩ

    ・Waveform 1(Cout:1462uF)



    ・Waveform 2(Cout:7072uF)



    Regards.

  • Hi Shotaro,

    These results looks fine.

    Do you have any other questions ?

    Best Regards,

    Rakesh

  • Hi Rakesh.

    Thanks for the confirmation.
    I understand that it works correctly when set to "fast slew rate".

    When set to "dvdt mode" (PGTH pin=GND), the voltage does not seem to return until Vout drops to 10V. Is this behavior in accordance with the IC specifications?
    I thought that the voltage would be restored after a delay of 110ms (UVLO_ton(dly)).

    In that case, is "10V" a value determined by the external components?

    Best Regards.

  • Hi Shotaro,

    To pass power fail situations, we need to set fast slew rate mode by PGTH pin = HIGH else output capacitance will discharge and fails the test.

    Best Regards,

    Rakesh