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TLV733P-Q1: Transient response measures

Koji Hayashi92
Mastermind 7030 points
Part Number: TLV733P-Q1


Hi TI-team

The output voltage overshoots when the input voltage is increased or the load current is decreased.

How can I reduce the output voltage overshoot ?

Please teach me.

My customer connected the output capacitance of 1uF and 10uF as close as possible to the output terminal, but there was no effect.

Best Regards,

Koji Hayashi

  • 0
    TI__Mastermind 37175 points

    Hi Koji,

    You have two conditions: A line transient and a load transient.
    How severe is the output voltage deviation?

    These transient are a function of the feedback loop and output capacitance.
    The feedback loop is complex and can also be impacted by the load current and load capacitance.

    First, ask your customer what the voltage rating of the 10uF and 1uF capacitors are.
    If the output voltage of the LDO is 40% or more of the rating of these capacitors, then the effective capacitance is often 50% or less of the rated capacitance.
    Choosing a higher rated capacitor will increase the effective capacitance and may help with these transient conditions.

    Alternatively you can ask your customer to increase the 10uF to 22uF.

    Thanks,

    - Stephen

  • 0 in reply to Stephen Ziel
    Mastermind 7030 points

    Hi Stephen-san

    Thank you for response.

    My customer changed to a larger capacitor but was reported that overshoot would not decrease.

    Do you have a waveform that confirms that increasing the capacitance of this IC reduces the overshoot ?

     

    Best Regards,

    Koji Hayashi

  • 0 in reply to Koji Hayashi92
    TI__Mastermind 37175 points

    Hi Koji,

    Figures 13-16 in the datasheet provide examples of load transients with and without load capacitance.
    I've copied figures 13-14 below for reference.

    Can you offer some oscilloscope shots of what you are seeing, and with what capacitors?
    That will help me understand what the next steps might be.

    Thanks,

    - Stephen

  • 0 in reply to Stephen Ziel
    TI__Mastermind 37175 points

    Hi Koji,

    Since it has been a week without a reply, we assume that this issue has been resolved.  If this is not the case, please feel free to reply.

    Thanks,

    - Stephen

  • 0 in reply to Stephen Ziel
    Mastermind 7030 points

    Hi Stephen-san

    I am so sorry for not replying.

    I am confirming with the customer.

    I will reply as soon as I can confirm.

    Best Regards,

    Koji Hayashi