Why it sometimes fast and sometimes slow ?

[ling1995]

Good afternoon~

Do you meet some situation like this :
The chip start up so slowly when cutting the current (about 10 seconds) and electrifying again.It need to wait about five seconds before it start up.(the performance is that the cue light flashed). If I cut the current between one and two senconds and then power on,the start-up will be fast.
The chip I used is STM32F407ZET6,and here the resistance in circuit is 10K (high pull)while the capacity is 1u (drop-down).How to solve it? Could you help me?

Thanks a lot.
PS: I have inserted the datasheet into STM32F407ZET6,please have a look if needed!

 

[CountMike]

That's pretty common with all electronics, Electrolytic capacitor, either at PSU or VRM/voltage regulator side. When power completely shut off and there's no draining circuit they stay charged for some time and when you restart immediately they are still charged and need less time. When very large time difference, it usually means a too large capacitor in power circuit somewhere. Needs longer time to charge/discharge. It's also common with amplifiers etc.