Datasheet

LPC81XM All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 4.3 — 22 April 2014 60 of 76
NXP Semiconductors
LPC81xM
32-bit ARM Cortex-M0+ microcontroller
14.3 XTAL Printed Circuit Board (PCB) layout guidelines
The crystal should be connected on the PCB as close as possible to the oscillator input
and output pins of the chip. Take care that the load capacitors C
x1
,C
x2
, and C
x3
in case of
third overtone crystal usage have a common ground plane. The external components
must also be connected to the ground plain. Loops must be made as small as possible in
order to keep the noise coupled in via the PCB as small as possible. Also parasitics
should stay as small as possible. Values of C
x1
and C
x2
should be chosen smaller
accordingly to the increase in parasitics of the PCB layout.