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LM5165: about ripple

Kaji@PAN
Mastermind 7340 points
Part Number: LM5165

Hi,

The output ripple is confirmed with the attached circuit. (COT control)
When the resistance of the output capacitor is 1.5 Ω, it becomes normal ripple.
If it is 1.2 Ω, the ripple may be small.
Is this because the ripple is so small that the COT control can not be performed normally?
Or is there no problem with small ripple?

Best Regards,

  • 0
    TI__Genius 16025 points

    Hi Kaji,

    According to our calculations assuming 800mohm DCR, and the values you provided, you should be expecting around 113mV of output ripple. As long as you have >1.1ohm of ESR, you should be stable.

    However, much improved noise immunity is achieved with the fixed 5V output version (LM5165X). The FB resistors of 383k and 124k with the adjustable version may couple noise to the FB pin, particularly if the FB resistor layout isn’t ideal.

    Let me know if you have further questions.

    Thanks,
    Anston