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TPS61231 maximum value of output capacitor

Steven Nyul
Prodigy 20 points
Other Parts Discussed in Thread: TPS61280A, TPS61230

Hello,

I intend to use the TPS61231 to supply 3.3V to a GPRS modem module. The load will be a repetitive 2A 1ms long pulse, repeated in every 4.6ms I have tried to use Webench to see the feedback loops response, but I could not change the output capacitance value and could not (would not?) simulate.

My question is: what is maximum output capacitor value that will not drive the device to oscillation.

Thanks!

Regards,

Steve

  • 0
    TI__Mastermind 46905 points

    the maximum COUT had been verified is 100uF. you can find this information at datasheet page 13.

    may  I know why do you need the large Cout?

    what is the input voltage? if li-ion battery, you can also have a look at TPS61280A. 

    Thanks

    Jasper Li

  • 0 in reply to Jasper Li
    Prodigy 20 points

    Hi Jasper,

    Thank you for your reply; my apologies for the delay responding to your question.

    As it turns out the TPS61231 (with output discharge) is not available at Digikey, so we will use the TPS61230 instead. The circuit will supply 5V @2A to an OEM cell modem that will draw about 2A in every 4.1ms. Their application note calls for a high value low ESR capacitor, up to about 1mF. This capacitor is actually at the output of your regulator, hence the question.
     I may have to adjust the voltage down anywhere from 4V to 5V.

    Since I need 5V output, I cannot use the TPS6128x-devices

    Thanks!

    Regards,

    Steve

  • 0 in reply to Steven Nyul
    TI__Mastermind 46905 points
    it is no problem for TPS61230 to operates at the 1mF output capacitor, but you need to optimized the feed forward capacitor value. refer datasheet page 14 and SLVA289 application note

    thanks
    Jasper Li