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TPS61178: some questions of TPS611781 and request of review schematics

robin Moon
Expert 1065 points
Part Number: TPS61178

Hi.

My customer is using to TPS611781RNWR.

he designed the circuit by referring to webench.

https://webench.ti.com/power-designer/switching-regulator/customize/4?noparams=0

However, some issues were discovered during testing.

Input : 3V-4.2V

output : 5.7V at 5A

when Ccomp is 1nF at no load,  output current was increased up to 400mA. and Inductor humming noise occurs.

I have some questions

1. I would like to know the detailed use of the Ccomp pin.

2. when this device using, how to decrease inductor humming noise.

3. Is there a way to use the TPS611781 product without connecting an external clock to the FREQ/SYNC pin?

Finally,

please review the schematic.

thanks,

regards,

robin.

  • 0
    TI__Mastermind 21565 points

    Hi Robin:

    May you share the waveform of Vin, Vout, SW and better with current of the inductance? 

    For your questions:

    1. I would like to know the detailed use of the Ccomp pin.

    [MQ] It's hard to say in short words, you can check the loop compensation in datasheet. 

    2. when this device using, how to decrease inductor humming noise.

    [MQ] I want to check the root cause about it. It could be caused by loop stable, or some protection function like UVLO

    3. Is there a way to use the TPS611781 product without connecting an external clock to the FREQ/SYNC pin?

    [MQ] It's OK to connect it with an proper resistance. Details are in the datasheet. 

  • 0 in reply to Minqiu Xie
    TI__Mastermind 21565 points

    Hi Robin:

    As long time no hear from you, I assume you have solved the issue. If not, just reply below. Thank you!

  • 0 in reply to Minqiu Xie
    Expert 1065 points

    Hi 

    Thanks for reply.

    I asked him for the waveform.

    plz wait to reply.

    thanks,

    regards,

    robin