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LM26420: Max output capacitor

K.Hamamoto
Guru 12155 points
Part Number: LM26420

Hi

Our customer ask us how much is the max output capacitor that you recommend.

Most of case, the min output cap is calculated from the max ripple inductor current.

On the other hands,the max value is depended on the loop characteristic.(The corner freq is decreased when the capacitor is increased.) And also it is affected to the soft start time.

However it is not mentioned anywhere at the datasheet about the loop characteristic of this device. So , could you give us the recommend max value if you have?

Best Regards,

Koji Hamamoto

  • 0
    Guru 12155 points

    In addition, the condition which are considering is as bellow,

    Vin=5V, Vo1=1.2V/2A, Vo2=3.3V/2A

  • 0 in reply to K.Hamamoto
    TI__Genius 10860 points

    Hi Hamamoto-san,

    while I dig a bit deeper into your request and check whether we have a maximum output capacitance specification for your operating conditions I can suggest to you to check section 8.2.1.2.4 Output Capacitor in the device datasheet (in case you haven't seen it yet) and check whether this could be a starting point for you. Besides, for Vo1 you could follow the recommendation of the LM26420 evaluation module for a start.

    I will come back to you after further checking internally.

    Thanks and best regards,

    Britta

  • 0 in reply to Britta Ruelander
    TI__Genius 10860 points

    Hi Hamamoto-san,

    did you have a look at my suggestions above? As I didn't hear back from you I am wondering whether this post might already be closed from your perspective. Please give a short feedback.

    Best regards,

    Britta

  • 0 in reply to Britta Ruelander
    Guru 12155 points

    Hi Britta-san,

    Thank you and I am sorry for the delay in my response.

    That was helpful advice for us. So please close this thread. I will re-open new thread if I got new question from the customer. 

    Best Regards,

    Koji Hamamoto