LPC1777 View Datasheet(PDF) - NXP Semiconductors.
Part Name
Description
MFG CO.
LPC1777
NXP Semiconductors.
'LPC1777' PDF : 120 Pages View PDF
NXP Semiconductors
LPC178x/7x
32-bit ARM Cortex-M3 microcontroller
Table 34. Recommended values for CX1/CX2 in oscillation mode (crystal and external
components parameters): low frequency mode
Fundamental oscillation
frequency FOSC
5 MHz to 10 MHz
Crystal load
capacitance CL
10 pF
Maximum crystal
series resistance RS
< 300
External load
capacitors CX1/CX2
18 pF, 18 pF
20 pF
< 200
39 pF, 39 pF
30 pF
< 100
57 pF, 57 pF
10 MHz to 15 MHz
10 pF
< 160
18 pF, 18 pF
20 pF
< 60
39 pF, 39 pF
15 MHz to 20 MHz
10 pF
< 80
18 pF, 18 pF
Table 35. Recommended values for CX1/CX2 in oscillation mode (crystal and external
components parameters): high frequency mode
Fundamental oscillation
frequency FOSC
15 MHz to 20 MHz
Crystal load
capacitance CL
10 pF
Maximum crystal
series resistance RS
< 180
External load
capacitors CX1, CX2
18 pF, 18 pF
20 pF
< 100
39 pF, 39 pF
20 MHz to 25 MHz
10 pF
< 160
18 pF, 18 pF
20 pF
< 80
39 pF, 39 pF
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 Cx1, Cx2, and Cx3 in case of
third overtone crystal usage have a common ground plane. The external components
must also be connected to the ground plane. 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. Smaller values of Cx1 and Cx2 should be chosen
according to the increase in parasitics of the PCB layout.
14.4 Standard I/O pin configuration
Figure 38 shows the possible pin modes for standard I/O pins with analog input function:
• 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.
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.
LPC178X_7X
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 5.5 — 26 April 2016
© NXP Semiconductors N.V. 2016. All rights reserved.
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