Datasheet
LPC1315_16_17_45_46_47 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
Product data sheet Rev. 3 — 20 September 2012 62 of 77
NXP Semiconductors
LPC1315/16/17/45/46/47
32-bit ARM Cortex-M3 microcontroller
In slave mode the input clock signal should be coupled by means of a capacitor of 100 pF
(Figure 30
), 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 31
and in
Table 18
and Table 19. Since the feedback resistance is integrated on chip, only a crystal
and the capacitances C
X1
and C
X2
need to be connected externally in case of
fundamental mode oscillation (the fundamental frequency is represented by L, C
L
and
R
S
). Capacitance C
P
in Figure 31 represents the parallel package capacitance and should
not be larger than 7 pF. Parameters F
OSC
, C
L
, R
S
and C
P
are supplied by the crystal
manufacturer.
Fig 30. Slave mode operation of the on-chip oscillator
Fig 31. Oscillator modes and models: oscillation mode of operation and external crystal
model used for C
X1
/C
X2
evaluation
Table 18. Recommended values for C
X1
/C
X2
in oscillation mode (crystal and external
components parameters) low frequency mode
Fundamental oscillation
frequency F
OSC
Crystal load
capacitance C
L
Maximum crystal
series resistance R
S
External load
capacitors C
X1
, C
X2
1 MHz - 5 MHz 10 pF < 300 18 pF, 18 pF
20 pF < 300 39 pF, 39 pF
30 pF < 300 57 pF, 57 pF
LPC1xxx
XTALIN
C
i
100 pF
C
g
002aae788
002aaf424
LPC1xxx
XTALIN XTALOUT
C
X2
C
X1
XTAL
=
C
L
C
P
R
S
L