lpc1778 NXP Semiconductors, lpc1778 Datasheet - Page 100

• Manufacturer Part Number: lpc1778
• Description: 32-bit Arm Cortex-m3 Microcontroller; Up To 512 Kb Flash And 96 Kb Sram; Usb Device/host/otg; Ethernet; Lcd; Emc
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC178x_7x
Objective data sheet
14.3 XTAL Printed-Circuit Board (PCB) layout guidelines
Table 28.
Table 29.
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
Fundamental oscillation
frequency F
5 MHz - 10 MHz
10 MHz - 15 MHz
15 MHz - 20 MHz
Fundamental oscillation
frequency F
15 MHz - 20 MHz
20 MHz - 25 MHz
1 MHz - 5 MHz
Fig 38. Oscillator modes and models: oscillation mode of operation and external crystal
model used for C
Recommended values for C
components parameters): low frequency mode
Recommended values for C
components parameters): high frequency mode
OSC
OSC
All information provided in this document is subject to legal disclaimers.
XTALIN
C X1
LPC1xxx
Rev. 00.04 — 8 July 2010
XTAL
X1
Crystal load
capacitance C
10 pF
20 pF
30 pF
10 pF
20 pF
30 pF
10 pF
20 pF
10 pF
Crystal load
capacitance C
10 pF
20 pF
10 pF
20 pF
/C
X2
XTALOUT
evaluation
C X2
X1
X1
/C
/C
L
L
X2
X2
in oscillation mode (crystal and external
in oscillation mode (crystal and external
Maximum crystal
series resistance R
< 300 Ω
< 300 Ω
< 300 Ω
< 300 Ω
< 200 Ω
< 100 Ω
< 160 Ω
< 60 Ω
< 80 Ω
Maximum crystal
series resistance R
< 180 Ω
< 100 Ω
< 160 Ω
< 80 Ω
32-bit ARM Cortex-M3 microcontroller
=
x1
S
S
LPC178x/7x
, C
L
C L
R S
x2
External load
capacitors C
18 pF, 18 pF
39 pF, 39 pF
57 pF, 57 pF
18 pF, 18 pF
39 pF, 39 pF
57 pF, 57 pF
18 pF, 18 pF
39 pF, 39 pF
18 pF, 18 pF
External load
capacitors C
18 pF, 18 pF
39 pF, 39 pF
18 pF, 18 pF
39 pF, 39 pF
002aaf424
, and C
© NXP B.V. 2010. All rights reserved.
C P
x3
in case of
X1
X1
100 of 112
/C
,
CX2
X2