MK66FX1M0 USB Feature with external power. Do I need to connect VREGIN and VOUT33 Pins?

[christhomas]

Hi all, 

I am using the MK66FX1M0VLQ18 microcontroller and want to use the USB feature. However, I don't to want to connect the USB 5V into VREGIN, instead want to power the microcontroller using an external LDO. For USB to still work, can I leave VREGIN unconnected and VOUT33 connected to 3.3V generated by my LDO. 

Thanks!

[Kan_Li]

No, you have to connect VREGIN to 5V but not limited USB 5V to get the internal USB module powered. VOUT33 can be left unconnected to any other device. Please kindly refer to the following for details.

Hope that helps,
Have a great day,
Kan

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[christhomas]

Thank you very much for your reply. Do you know the purpose of the USB1_VBUS pin? 

Thanks.