MK66 VREG_IN Mux

[brtaylor]

I'm starting to design a custom board around the MK66FX1M0 and intend on using the MKL02/MKL04 for using the standard Teensy 3.6 software stack. However, instead of using an external 3.3V regulator, I plan on using the builtin. According to the NXP documentation, the input-power mux will automatically select between VREG_IN0 and VREG_IN1 depending on which has the higher voltage level during power-up. But there is an option to override that in software. Am I correct to assume that this override is not used? In other words, can I use both VREG_IN inputs? Also is VREG_OUT set to 3.3V?

Thanks much!
Brian

 

[PaulStoffregen]

Yes, I believe you can control this using the SIM_USBPHYCTL register. It's documented in section 13.2.3 on pages 236-237 of the K66 reference manual.