Need To Disable CYPD3177 For Optional External Power

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MiNo_4460176
Level 1
Level 1

I need to disable the CYPD3177 to provide power from an external barrel power connector. I intend this power to come in after the pass fets that are controlled by VBUS_FET_EN. Can the VBUS_FET_EN be used for this purpose? Is there an alternate method?

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1 Solution

Hello,

Yes, this could work looking at the VGS(th) of your FET.

-You could use a power OR-ing method as well or a SPDT switch between the FETs and external power supply. This would take care of the back-powering in case the host is also connected.

-Could you please let us know how the BCR is powered?

Best Regards,

Sananya

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3 Replies
Sananya_14
Moderator
Moderator
Moderator
750 replies posted 500 replies posted 250 solutions authored

Hi,

It is not possible to control the FETs using VBUS_FET_EN through a HPI command from an EC. Could you please let us know when you would like to disable the BCR and provide power directly?

Best Regards,

Sananya

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I would like to provide power directly before the usb cable is connected and the rest of the pcb is off. I also want to make sure it is safe and will not back drive the host when connected. In terms of the circuit to use VBUS_FET_EN, I was thinking of doing this...

pastedImage_0.png

Where J1 Is just a 2 pin jumper, which is open when I want to use usb power and closed when I want to power directly from external source.

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Hello,

Yes, this could work looking at the VGS(th) of your FET.

-You could use a power OR-ing method as well or a SPDT switch between the FETs and external power supply. This would take care of the back-powering in case the host is also connected.

-Could you please let us know how the BCR is powered?

Best Regards,

Sananya

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