LPC540xx
NXP Semiconductors
32-bit ARM Cortex-M4 microcontroller
13.5.1 RTC Printed Circuit Board (PCB) design guidelines
• Connect the crystal and external load capacitors on the PCB as close as possible to
the oscillator input and output pins of the chip.
• The length of traces in the oscillation circuit should be as short as possible and must
not cross other signal lines.
• Ensure that the load capacitors CX1, CX2, and CX3, in case of third overtone crystal
usage, have a common ground plane.
• Loops must be made as small as possible to minimize the noise coupled in through
the PCB and to keep the parasitics as small as possible.
• Lay out the ground (GND) pattern under crystal unit.
• Do not lay out other signal lines under crystal unit for multi-layered PCB.
LPC540xx
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© NXP Semiconductors N.V. 2018. All rights reserved.
Product data sheet
Rev. 1.8 — 22 June 2018
150 of 168
NXP [ NXP ]
