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UA78M33IKVURG3

steve phillips
Prodigy 10 points


UA78M33IKVURG3

I need to improve the transient response of this device, as I am getting 1 volt drop outs for 200uS duration, with an ESP32 wifi chip as a load. I have tried a 1000uF electrolytic on the linear regulator output and this solves it. But is this acceptable? I.e. will this be stable?

  • 0
    TI__Expert 5231 points

    Hi Steve,

    Thank you for the question. A 1000 uF capacitor is quite large but it is true that a large output capacitance will enhance transient response. I would assume that with some a large capacitor start up time increases, is this something you notice? 

    Have you tried a ceramic capacitor? Having a lower ESR could also help with improving the transient response and ceramic capacitors tend to have lower. 

    Thank you,

    Josh Nachassi

  • +1 in reply to Josh Nachassi
    Prodigy 10 points

    Thanks so much for your reply. I'll try a ceramic next. My main issue is, I'm just concerned I'd be OK testing with this 1000uF Electrolytic, and I won't damage the LDO regulator? I understand it's internally current limited?

    Thanks

  • 0 in reply to steve phillips
    TI__Expert 5231 points

    Hi Steve,

    No problem at all. It will not damage the device by having a larger or smaller output cap it is mainly for stability. I would try a smaller ceramic capacitor though because then you also don't need to worry about a lot of discharge when the device powers off.

    Please let me know if you have any further questions. 

    Thank you,

    Josh Nachassi