• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 62 subscribers
  • Views 1202 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Input and output capacitor for LM2576

RAMESH DURAISAMY
Prodigy 70 points
Other Parts Discussed in Thread: LM2576

Dear All,

Good day!
I am doing a Power supply (+5V / 3A) for GSM modem (SIM900) based application. Regarding the LM2576 Input and output capacitors in the application diagram shows that, 100uF and output side is 1000uF. 
Generally the power supplies having less capacitance value than the input side to avoid the back flow of charged supply through the regulator.

But in the case of LM2576 Typical application (for 5VDC / 3A) is showing that input side 100uF and output side 1000uF. TI gives always right solution for all their products. However, please clarify my doubt in this regards.

Thank you all.
Regards,

Ramesh Duraisamy.

  • 0
    TI__Expert 3870 points

    Hello Ramesh,

    In the case of step-down regulators, the input capacitor is a selected so that it is able to hold-off enough charge for immediate current demands during every switching cycle and at the same time provides a low enough input current ripple so that internal circuitry is not disturbed.  The output capacitor also mitigates output voltage ripple, but more importantly is used for the control-loop stability.  Both of the input/output capacitor values recommended by the datasheet have been tested.  If you look at other step-down regulator datasheets you'll see that the same holds true. You can also use our Webench online tools for simulations and additional information.

    Best Regards,

    -JP

  • 0 in reply to Juan Paulo Fung
    Prodigy 70 points

    Hi Juan,

    Good day!
    Thank you very much for your clear idea. I knew that the given values are tested etc... However, there was a small doubt about the capacitor selection. Now it is cleared. Thank you once again.

    Nice day.

    Kind Regards,

    Ramesh.