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TLV70433DBVEVM-712: Output Voltage incorrect when input have a huge ripple

Part Number: TLV70433DBVEVM-712
Other Parts Discussed in Thread: TLV704, BQ24610, TPS709

Hi everyone,

I'm using TLV70433 and it's all good and stable.

Here is my working circuit.

The problem is when CE1 disconnected, and Vin have a huge ripple (the photo below).

Even the lowest voltage is still over 15V.

But I got less than 1V on Vout of TLV70433.

Is there any frequency or amplitude of input ripple that make TLV70433 fail?


  • Hello,

    The Vin waveform you have shouldn't be an issue that would cause TLV704 to fail. Section says that the only issues with having no input capacitance arise when there are large load transients, so if you are not testing with load transient then there should be no issue. 

    In your scope shot there is 2 channels that look like the same voltage. Are they both on Vin? Can you provide another scope shot showing both Vin and Vout?

    Also for this test, is there any load?

    Best regards,


  • Hi,

    Thanks for the reply.

    Here is my simplified test circuit (I take off the CE1, with CE1 this circuit works fine)

    When the charge circuit cut-off, the Vin is steady 19V and Vout 3.3V is steady. (Vout loading is about 23mA)

    But when I let the BQ24610 charge the battery, the Vin have a huge ripple and I got only 1V on Vout. (Guess ripple is from BQ24610)

    Here is my Vin and Vout scope pic.

    Green one is Vin, Red one is Vout.

    Thanks a lot

  • Hello,

    It is hard to say why this is happening because I'm not familiar with the BQ24610. It seems that the TLV704 is stable even though the input is oscillating. Is there a chance that the BQ24610 is somehow affecting the ground and shifting it? 

    Are you wanting to exclude CE1 to reduce board space and cost? 



  • Hi,

    Thanks for the reply.

    The ground of BQ24610 is directly connect to ground of this board, so I don't think BQ24610 can shift the ground.

    There is a manufacture problem that might let CE1 disconnected sometimes and it might pass the PCB test course CE1 might connect sometimes.

    Of course we deal with the manufacture problem.

    But we still wonder why this signal cannot make TLV70433 work properly, since everything seems ok on datasheet.

    Anyway, thanks for the help and have a good one.

  • Hi Nick,

         In the line transient chart from datasheet, the response time is pretty slow. And almost 25ms from transient to steady-state.

    Since the input ripple voltage amplitude and frequency is pretty high. Could you help to check if the loop gain and bandwidth of TLV70433 can stable the output voltage.

    Vin(max) : 21.2V

    Vin(min) : 16.8V

    Ripple Frequency : 570kHz



  • Hi, 

    TLV704 is known to be susceptible to EMI and input noise that could affect the voltage on the internal node. Do you think you could try TPS709 to see if it will help with this problem? 

    Jason Song

  • Hi,

    Thanks for the reply, but I don't have the TPS709 in hands.

    So you mean these signal is not workable for TLV70433?

    I just want the answer of this and why since there isn't a graphic explain the frequency response of this IC.


  • To use TLV704, you will need to reduce the noise on the input line as we know this device is susceptible to input noise that could change the internal reference and result in a shifted output.