Power K64F with external power supply

[fahimrahman]

I've got a FRDM-K64F that I want to power up using an external power source. I put 5V through V_in (pin 16) and the connected the ground to my voltage regulator. I can see the Ethernet light turn on, indicating there is some power going through, but the main 'on' light isn't on, and nothing happens when I press the 'reset' button.

To double check that is meant to work, I connected it to my PC using the USB, hit 'reset', and it worked fine.

How can I run this with an external power supply?

Thanks!

[michaelkoller]

Hey there!

I have run into the same problem as OP and I have tried two things.

I tried my power supply Voltcraft VLP-1405 with 5V and I have tried the 5V which are supplied from a DC/DC stepdown converter, that I ultimately want to use.

There is only the red light on, as the OP reported, not the green one.

Which steps can I take to avoid this?

Also, if this I should not revive this thread, please tell me so I can open a new one.

Cheers,

Michael

[maksim_lipskiy]

H.!
I made a smooth flow of power to the power was set for 100 milliseconds.

[jeremyzhou]

Hi Fahim,

Before I answer your question, I'd like to check with you about whether you connected the external 5V supply to VDD pin directly or not.

Have a great day,
Ping

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[fahimrahman]

I believe so, yes. 5V to pin 16, ground to pin 14.

[jeremyzhou]

Hi Hi Fahim,

I've reproduce your procedure to supply the board from a external 5 voltage, however the board can work well, as the Fig 1 illustrates.

                                                                            Fig 1

Have a great day,
Ping

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[maksim_lipskiy]

Your DC power very long risetime (for example  DC-HY5002 about 400 ms). Therefore, the board is working.
If you are using a power supply unit SPS-026-05, the board will not work. Because risetime very small.