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LP5907: VEN question

Peter Xu
Expert 3235 points
Part Number: LP5907

Hi Team,

My customer wants to use a 1.2V with 20mV ripple voltage as VEN when rising. Is it feasible?

Best Regards,

Peter

  • 0
    TI__Genius 16846 points

    Hey Peter, 

    This part needs a minimum of 1.2V for enable to be considered engaged.

    It could be possible that the 20mV ripple is not detected by the part, but it is not recommended to have an unreliable connection on EN. This connection could be suitable for the application, but it would have to be a decision the customer makes.

    Have you considered adding a capacitor to the EN pin so that the ripple is minimized?

    Best,

    Juliette

  • 0 in reply to Juliette
    TI__Expert 3235 points

    Hi Juliette,

    Actually EN is linked with a LDO output. And 20mV is the worst condition. I wonder how much value of ripple voltage can be neglected. And if I add a capacitor to the EN pin, which value should I choose? Is it decided by the ripple frequency?

    Best Regards,

    Peter

  • +1 in reply to Peter Xu
    TI__Genius 16846 points

    Hey Peter, 

    Once the 1.2V threshold is passed on the EN pin, the part is guaranteed to work. If it dips lower than 1.2V but is greater than 0.4V, the part is in an unknown state. It will likely stay on, but a capacitor can help ensure the line stays stable.

    A 1uF capacitor can be added to make sure the voltage on the EN pin stays high. However, this can affect turn-off time, if that is a concern the customer may have. The 1uF capacitor may not be necessary, but it would depend on the application/would be a decision the customer makes. 

    Best,

    Juliette