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Is there any LDO product that can work well without large input capacitor

Other Parts Discussed in Thread: TPS737

Hi,

I'm looking for a LDO that can work fine without large input capacitors.

The most products that I found will need a 10 uF capacitor at the input of the LDO, but I'm not sure how much will the performance be degraded if I remove the capacitors at the input.

In my design case, the input of the LDO will be 5 V while the output will be 3.3 V with about 0.5A output current.

I really appreciate it if someone can give me some suggestions or recommendations.

  • Hi Muqi,

    Many LDOs do not require an input capacitor for stability; however, the input capacitor will help with AC performance (transients, PSRR, noise) due to the prefiltering provided by the capacitor.  We also recommend trying to balance your input and output capacitors in order to reduce the current demand on the LDO supply during transients.

    The parametric search tool we provide can help you select the best LDO for your application based on your application needs.  As your input and output are common rails you will initially have a lot of results; however, you can narrow these by deciding if you need an adjustable, fixed or programmable output or adding some other requirement.  

    One example that may work for your application is TPS737.

    Very Respectfully,

    Ryan

  • Hi Ryan,

    Very thanks for your reply!

    I noticed that there are lots of options. Without the de-coupling capacitors at the input, the performance may be a little degraded, but it won't cause problems in my current applications.

    Best regards,

    Muqi