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
LPC1xxx
XTAL1
Ci
Cg
100 pF
002aae835
Fig 36. Slave mode operation of the on-chip oscillator
In slave mode the input clock signal should be coupled by means of a capacitor of 100 pF
(Figure 36), with an amplitude between 200 mV(RMS) and 1000 mV(RMS). This
corresponds to a square wave signal with a signal swing of between 280 mV and 1.4 V.
The XTALOUT pin in this configuration can be left unconnected.
External components and models used in oscillation mode are shown in Figure 37 and in
Table 34 and Table 35. Since the feedback resistance is integrated on chip, only a crystal
and the capacitances CX1 and CX2 need to be connected externally in case of
fundamental mode oscillation (the fundamental frequency is represented by L, CL and
RS). Capacitance CP in Figure 37 represents the parallel package capacitance and should
not be larger than 7 pF. Parameters FOSC, CL, RS and CP are supplied by the crystal
manufacturer.
LPC178X_7X
Product data sheet
LPC1xxx
XTALIN
XTALOUT
XTAL
CX1
CX2
L
=
CL
CP
RS
002aaf424
Fig 37. Oscillator modes and models: oscillation mode of operation and external crystal
model used for CX1/CX2 evaluation
Table 34. Recommended values for CX1/CX2 in oscillation mode (crystal and external
components parameters): low frequency mode
Fundamental oscillation
frequency FOSC
1 MHz to 5 MHz
Crystal load
capacitance CL
10 pF
Maximum crystal
series resistance RS
< 300
External load
capacitors CX1/CX2
18 pF, 18 pF
20 pF
< 300
39 pF, 39 pF
30 pF
< 300
57 pF, 57 pF
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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