MK22FN : VREGIN pin is powered when MCU VDD is off.

[koichisakagami]

Dear community,

We have been developing our product with MK22FN1M0AVMC12.

We worry about a situation as follows.

The VREGIN pin is connected to VBUS(5v) with USB connector.
When 5v is applied to the  VREGIN pin, the MCU 3.3v voltage is not applied to VDD pin yet.

[Question]
    Does such a situation have any problem for MK22 ?
    For example,
    does it decrease the lifetime of MK22 ?

Best Regards,
    Koichi Sakagami

[jeremyzhou · Accepted solution]

Hi  Koichi Sakagami,

According to reference manual, the USB regulator should be put into STANDBY mode when the chip is in Stop mode.

When the MCU is not powered by the VDD which is almost equal to the MCU enters the low power mode.

So I'd highly recommend that you should eliminate the put the USB cable to a USB host while the MCU is not powered.
Have a great day,
Ping

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[koichisakagami]

Dear Ping san,

Thank you for your answer.

I got it.

Best Regards,

Koichi Sakagami