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TPS62410-Q1: About Overshoot measures of TPS62410-Q1

Noritomo Harukawa
Intellectual 990 points
Part Number: TPS62410-Q1
Other Parts Discussed in Thread: TPS62410

The TPS62410-Q1 is used in the following configuration.
*The output capacitor (C5) uses "CGA6P1X7R1C226M250AC".

Overshoot was confirmed at VOUT 1 output at power on. (Overshoot of about 240mV)

This overshoot does not affect the operation.
However, it wants to eliminate the overshoot as for hope.

Q1.
It is possible to increase the output capacitor capacity as a overshoot countermeasure.
Could you tell me if there are other effective measures?

-Harukawa

  • 0
    TI__Guru*** 147240 points
    Hi Harukawa-san,

    Thank you for sharing your schematic and waveform.

    You need to adjust the values of C3 and C4 to make up for the smaller FB resistors. This app note, found on the product page, explains more: www.ti.com/.../slyt469.pdf

    As well, can you add Vin and EN to the scope? Is there any load?

    Are R1 and R2 both installed as 10k? This seems odd.
  • 0 in reply to Chris Glaser
    Intellectual 990 points

    Thank you for your reply.

    > As well, can you add Vin and EN to the scope? Is there any load?

    Concerning that, it is currently being confirmed.

    > Are R1 and R2 both installed as 10k? This seems odd.

    In the circuit, R1 and R2 use 10k.
    I think that 2.5V will be applied to MODE pin.
    I think that it also meets the high level of the MODE pin.

    Is it odd to use 10k for R1 and R2?

    -Harukawa

  • 0 in reply to Noritomo Harukawa
    TI__Guru*** 147240 points
    Normally, 2 resistors would be there so that either 1 can be installed in order to change the logic state of the MODE pin. With 2 resistors, the pin is indeed high, but current is uselessly wasted through the resistors. The same end results (a high pin) can be made by just installing R1 and leaving R2 open. This saves power and cost.
  • 0 in reply to Chris Glaser
    Intellectual 990 points
    Thank you for your reply.

    Thank you for explaining R1, R2.
    I was satisfied with your pointed out.


    > As well, can you add Vin and EN to the scope? Is there any load?

    These information will be obtain in 10/10 (JST).
    Please wait for a little while longer.

    -Harukawa
  • 0 in reply to Noritomo Harukawa
    Intellectual 990 points

    I'm sorry. No information is available from the customer yet.

    So I tried simulating with TINA.
    As a result of the simulation, overshoot of about 50 mV was confirmed.
    (See "TINA Simulation_Result(1).JPG" and "TINA Simulation_Result(1_schmatic).JPG")

    Q1.
    Will you provide advice on the cause of overshoot at power on and measures to prevent overshoot?

    -Harukawa

  • 0 in reply to Noritomo Harukawa
    Intellectual 990 points

    > As well, can you add Vin and EN to the scope? Is there any load?

    I am sorry to have kept you waiting.
    We obtained waveform diagrams of VIN, EN and VOUT from customers.
    (Please see TPS62410 OverShoot(3.3V).xlsx)

    The load is 40 mA.

    Q1.
    Please provide advice on the cause and countermeasure of overshoot.

    -Harukawa

    TPS62410 OverShoot(3.3V).xlsx

  • 0 in reply to Noritomo Harukawa
    TI__Expert 5425 points
    During startup the inductor current must be higher compared to what is required for a steady state operation or operation at no load. This higher current is needed to charge the output capacitor. At the time the nominal output voltage is reached the inductor current is too high and needs to be reduced. This takes some time and during this time excessive current further charges the output capacitor. So you will see an overshoot.
    To minimize the overshoot in this case you can make the output voltage detection faster. This reduces the time of the excessive charging of the output capacitor.
    The voltage detection will become faster if you increase the feedforward capacitance (C3 for VOUT1). Since the resistance values in the feedback divider which you have used are lower than recommended in the datasheet, the feedforward capacitance is too low anyway and should be adjusted for optimizing the control loop. The application note Chris mentioned above explains that in detail.