LPC1776FBD208 NXP Semiconductors, LPC1776FBD208 Datasheet - Page 105

• Manufacturer Part Number: LPC1776FBD208
• Description: The LPC1776 is a Cortex-M3 microcontroller for embedded applications featuring a high level of integration and low power consumption at frequencies of 120 MHz
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC178X_7X
Objective data sheet
14.3 XTAL Printed-Circuit Board (PCB) layout guidelines
14.4 Standard I/O pin configuration
Table 34.
Table 35.
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.
Figure 39
The default configuration for standard I/O pins is input with pull-up enabled. The weak
MOS devices provide a drive capability equivalent to pull-up and pull-down resistors.
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
•
•
•
•
•
Digital output driver: Open-drain mode enabled/disabled
Digital input: Pull-up enabled/disabled
Digital input: Pull-down enabled/disabled
Digital input: Repeater mode enabled/disabled
Analog input
shows the possible pin modes for standard I/O pins with analog input function:
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.
Rev. 3 — 27 December 2011
Crystal load
capacitance C
10 pF
20 pF
30 pF
10 pF
20 pF
10 pF
Crystal load
capacitance C
10 pF
20 pF
10 pF
20 pF
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 
< 200 
< 100 
< 160 
< 60 
< 80 
Maximum crystal
series resistance R
< 180 
< 100 
< 160 
< 80 
x1
and C
32-bit ARM Cortex-M3 microcontroller
x2
should be chosen smaller
x1
S
S
LPC178x/7x
, C
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
18 pF, 18 pF
External load
capacitors C
18 pF, 18 pF
39 pF, 39 pF
18 pF, 18 pF
39 pF, 39 pF
, and C
© NXP B.V. 2011. All rights reserved.
x3
in case of
X1
X1
105 of 120
/C
,
CX2
X2