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YongseokJeon
Level 4
Level 4
Distributor - Changnam (South Korea)
50 replies posted 50 questions asked 25 replies posted

Dears,


To reduce power consumption, power is not supplied to the MCU for a certain period of time. We don't use deepsleep or hibernate.
In our schematic, P12.5 is connected to an external IC and we want to keep P12.5 at 3.3V.
Since P12.5 is connected to the pull-up resistor, if P12.5 is set to HI-Z when power is applied to the MCU, it will be maintained at 3.3V.
Is there a way to maintain 3.3V even when the MCU is powered off?

Thanks and Regards,
YS

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1 Solution
YongseokJeon
Level 4
Level 4
Distributor - Changnam (South Korea)
50 replies posted 50 questions asked 25 replies posted

Hello Andri,

I tested it by adding an external pull-up resistor to P12.5 of CY8CKIT-062-WIFI-BT. I set the P12.5 to HI-Z.

When the MCU power is applied, it is maintained at 3.3V.

However, when the MCU is not powered, it remains at approximately 1V.
At this time, I removed the USB cable and applied 3.3V of external power to the pull-up resistor.

Thanks and Regards,
YS

 

 

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3 Replies
ADSW
Moderator
Moderator
Moderator
250 sign-ins 50 solutions authored 25 likes received

Hello @YongseokJeon , 

You can set P12.5  pulled-up externally. 

Warm regards
Andri

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YongseokJeon
Level 4
Level 4
Distributor - Changnam (South Korea)
50 replies posted 50 questions asked 25 replies posted

Hello Andri,

I tested it by adding an external pull-up resistor to P12.5 of CY8CKIT-062-WIFI-BT. I set the P12.5 to HI-Z.

When the MCU power is applied, it is maintained at 3.3V.

However, when the MCU is not powered, it remains at approximately 1V.
At this time, I removed the USB cable and applied 3.3V of external power to the pull-up resistor.

Thanks and Regards,
YS

 

 

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ADSW
Moderator
Moderator
Moderator
250 sign-ins 50 solutions authored 25 likes received

Hello @YongseokJeon , 

That's sounds good.. 
You should use an external voltage of 3.3V not from the MCU's VDD for your pull-up, as long as both devices use the same ground it will maintain 3.3V on that pin. 
But it would be different case if your both of devices has separate ground( isolated area ), you need to make it isolated too.. 

Warm regards, 


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