LPC12D27FBD100 NXP Semiconductors, LPC12D27FBD100 Datasheet - Page 38

• Manufacturer Part Number: LPC12D27FBD100
• Description: The LPC12D27FBD100 is a ARM Cortex-M0 based microcontroller for embedded applications featuring a high level of integration and low power consumption
• Manufacturer: NXP Semiconductors

NXP Semiconductors
12. Application information
LPC12D27
Product data sheet
12.1 XTAL input
12.2 XTAL Printed Circuit Board (PCB) layout guidelines
The input voltage to the on-chip oscillators is limited to 1.8 V. If the oscillator is driven by a
clock in slave mode, it is recommended that the input be coupled through a capacitor with
C
capacitor to ground C
mode, a minimum of 200 mV(RMS) is needed.
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
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
accordingly to the increase in parasitics of the PCB layout.
Fig 23. Slave mode operation of the on-chip oscillator
i
= 100 pF. To limit the input voltage to the specified range, choose an additional
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 20 September 2011
g
which attenuates the input voltage by a factor C
XTALIN
LPC1xxx
C i
100 pF
x1
and C
002aae788
32-bit ARM Cortex-M0 microcontroller
C g
x2
should be chosen smaller
x1
,C
LPC12D27
x2
, and C
i
/(C
© NXP B.V. 2011. All rights reserved.
i
+ C
x3
g
). In slave
in case of
38 of 46