Hi,
The Figure below shows the basic board connections used to power the LPC15xx, connect the external crystal and the 32kHz oscillator for the RTC, and provide debug capabilities via the serial wire port.

In addition you can use the OM13056 LPCXpresso board for LPC1549 as reference.
http://www.nxp.com/assets/downloads/data/en/schematics/LPC1549_LPCXpresso_v2_schem_Rev_C.pdf
Have a great day,
Sol
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