TPS561201: Input capacitor for power backup

Hi Hijack,

If the output capacitance is too large, the loop will be unstable, when do you want to add the backup capacitors to the output? After power off?

Best Regards,
Shawn

Hi I understood from your reply that I can not add while power ON as loop will be unstable. So what is mechanism after power off.
Or can I connect at the input side as load

Hi,

In theory, it is feasible. But large input capacitance is needed to provide power after power off, and also the input voltage will increase slowly because the large input capacitor, this will affect the startup time.

In addition, I think 1000uF is just not enough. What is the application? Why dose the microcontroller need some time to save parameter and send information after power off?

Shawn

One correction is backup time required only about 25ms not 150ms as mentioned earlier. Microcontroller need this to inform to server through gateway that there is no power now and device is going to off. This help to know the control room person about the status. this is used in street light application