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TLV62090 Output capacitor max value

KIYOSHI NARISAWA1
Expert 1510 points
Other Parts Discussed in Thread: TLV62090, TPS62067

Dear TI

Output capacitor values are lemited for max value at each inductor  as below.

  

How were these max value decided?

 If is there any formula, please let me know.

Becase TLV62090 will be conneced many devices in customer's application like add more 170uF.

I'll check stability by use FRA, but customer want to know the reason how to decide  170uF max value.  

Thank you and best Regards

K.Narisawa

  • 0
    TI__Guru**** 150900 points

    DCS-Control and the TLV62090 can support larger amounts of output capacitance than previous devices (such as TPS62067).  In most cases, stability is still sufficient beyond the ranges in the D/S.

    In order to have a finite amount of simulations and testing done, there has to be an upper end to the values put in the D/S.  The values in the D/S have been simulated and/or tested for stability over a variety of conditions, such as input voltage, output voltage, and temperature.  It is very safe to use what is in the D/S.

    I do not see any issue with 170uF Cout for this device.

  • 0 in reply to Chris Glaser
    Expert 1510 points

    Hi Chris-san,

    Thank you for your quick response always.

    When you check stability test, what is your criteria?

    For example, Phase is 45deg over at Zero Gain... or ringing at trasiet response etc.

    If I will check phase margine, what does input voltage into feedback loop? 3mV pk-pk? or 10mV pk-pk?

    Could you please reply to below mail address if you can't reply on this?

    narisawa-k@clv.macnica.co.jp

     Thank you and bestregards

    K.Narisawa  

  • 0 in reply to KIYOSHI NARISAWA1
    TI__Guru**** 150900 points

    This app note explains how to measure a bode plot on DCS-Control: http://www.ti.com/lit/an/slva465a/slva465a.pdf

    We usually look for phase margin above 30 or 45 degrees and less than 2 rings in the transient response as indicators of stability.