Linkit 7688 power supply

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Andre.Schoeman
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Joined: Tue Jan 19, 2016 7:36 am

Linkit 7688 power supply

Post by Andre.Schoeman » Tue Jan 19, 2016 8:00 am

Hi

The Linkit 7688 documentation is a little vague on the power supply pins. Can someone please add some detail or point me to a more detailed document.
The Linkit 7688 has the following power supply pins,

5V
VCC
3V3
GND

(not available on the header is 5VUSB coming from the USB power connector

I have looked at the Linkit 7688 schematic to try to see how they are used. The power supply seems over designed given all the additional MOSFETs to try to switch certain paths on/off depending in the actual power supplied. Was that really necessary.

The naming convention changes from schematic to the standard I/O diagram.
VCC is actually 3V3_IN on the schematic.
5V is 5V_OUT on the schematic.

If I want to power the board from 3V3 then I should apply it to VCC(3V3_IN), right?
I assume that I can power the board from 5V even though the schematic says it's 5V_OUT.
It's 5V out from the USB socket point of view, but is the input to the on board 3.3V regulator.

I may have answered my own question, but please confirm anyway?

What is the minimum current consumption in low power / sleep mode? (I assume that there is one?)

Another question,

Is MPU_RESET active low or active high.

It seems like a nice product. I look forward to using it.

Thanks
Andre

shijian.fang
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Joined: Thu Oct 16, 2014 9:29 am

Re: Linkit 7688 power supply

Post by shijian.fang » Tue Jan 26, 2016 4:50 pm

Hi,

Refer to the diagram below.

Image

WiFi button and MPU button active low.

Not sure about low power mode or sleep mode.

niteslim
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Joined: Wed Mar 16, 2016 9:44 pm

Re: Linkit 7688 power supply

Post by niteslim » Wed Mar 16, 2016 9:52 pm

Linkit 7688 Duo can be powered via the Vcc (3.3v) and the 5V_out (5v). Things to note though, the board consumes around 800mA on startup, be sure that your supply can provide at least that amount.
I have tried using 7805 (STM 7805ACV / 1A) to power the board, the regulator heats up really fast.

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