LPC54608 XTAL

[実奥山]

I do not use XTAL. I use the internal clock.

If I don't use external XTAL, Should I connect the K4 pin to GND and open the J4 pin?

[carstengroen]

According to the datasheet, yes (don't mind the typo at the "XTALIN" pin where they write "the RTC oscillator is disabled" :smileyhappy:

(I also do this in all my designs, works perfectly)

One of my designs: