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TLV760: Output Capacitor

T Kishi
Genius 4425 points
Part Number: TLV760

Hi

My customer has question.

I understand that there is no upper limit on the output CAP of TLV 760.
Customers are considering using 100 uF electrolytic capacitors.
■100uF@EKY350EC3151MHB5D
I think that there is no problem, but are there any concerns?

Regard

Tkishi

  • 0
    TI__Mastermind 23361 points
    Hi Kishi-san,

    According to the requirement of the output cap on the datasheet, 100uF electrolytic capacitor should be okay.

    Regards,
    Jason Song
  • 0 in reply to Jason Song
    Genius 4425 points
    Hi Jason

    TLV760 has no regulation of rise time (soft start function).
    Is there no problem when considering inrush current at output capacity of 100uF?

    Regard
    T Kishi
  • 0 in reply to T Kishi
    TI__Mastermind 23361 points
    Hi Kishi-san,

    If you have bigger cap, your in rush will be higher. To help with in-rush, you can will need to make your output cap smaller. This could be accomplished by simply moving some of the output capacitance to the input side of the LDO. This allows for the same system level filtering while reducing the amount of inrush current to charge the output capacitors at startup.

    In order to better understand if in-rush will be an issue for your application. I recommend you take the startup scope shot of your Vin, Vout and Iout with the caps you plan to have on the output. I will be able to support further when this information is available.

    Regards,
    Jason Song
  • 0 in reply to Jason Song
    Genius 4425 points
    Hi Jason


    Once confirmed, the above electrolytic capacitor was 150 uF. Still no problem?
    The comment you say is the same for a capacity of 150uF, is not it?
    Since the TLV 760 has no upper limit of the output capacity, we think that there is no problem with the capacitance value.

    Best Regard
    T Kishi
  • 0 in reply to T Kishi
    TI__Mastermind 23361 points

    Hi Kishi-san,

    150uF should be okay according to the datasheet. Again,  I recommend you take the startup scope shot of your Vin, Vout and Iout with the caps you plan to have on the output. 

    Regards, 
    Jason Song

  • 0 in reply to Jason Song
    Genius 4425 points

    Hi Jason

    Thank you For reply.

    I want you to see the waveform.

    TLV760.pdf

    Although it is stuck on the current limit at startup,Then it is operating normally.

    I think that I am doing the following actions.
    1.Charge to C at startup, Due to the inrush current for short protection works.
    2.Since there is no load, the output voltage rises gradually
    3.A charge to C begins again.
    4.Inrush current flows again, but since C is charged to some extent, few current flows

    Performing normal operation, but are there any problems that I can think about?
    I will be saved if you give me your comment.

    Best Regard

    T Kishi

  • 0 in reply to T Kishi
    Guru 140200 points
    Hi Kishi,

    such a high output cap is a bit unusual for a 100mA regulator, but it should work.

    Have you thought about mounting a protection diode from output to input? Can the input voltage be suddenly removed or even short circuited to ground in your application? Then you should mount this protection diode. I would take a Schottky.

    Kai
  • 0 in reply to T Kishi
    TI__Mastermind 23361 points

    Hi Kishi-san, 

    Initially the higher in-rush current is during the time when Cin is being charging, then the current gets back to normal until device has been fully turned on. Since there is a big Cout on the output, the in-rush current gets higher again to charge the output cap. This seems to be normal operation of the device when a large Cout is connected at the output. 

    Regards, 
    Jason Song