LPC2420_60

Manufacturer Part NumberLPC2420_60
DescriptionNXP Semiconductors designed the LPC2420/2460 microcontroller around a 16-bit/32-bitARM7TDMI-S CPU core with real-time debug interfaces that include both JTAG andembedded trace
ManufacturerNXP Semiconductors
LPC2420_60 datasheet
 


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NXP Semiconductors
Table 20.
Fundamental oscillation
frequency F
15 MHz to 20 MHz
20 MHz to 25 MHz
14.4 RTC 32 kHz oscillator component selection
Fig 31. RTC oscillator modes and models: oscillation mode of operation and external
The RTC external oscillator circuit is shown in
integrated on chip, only a crystal, the capacitances C
externally to the microcontroller.
Table 21
capacitance of the crystal and is usually specified by the crystal manufacturer. The actual
C
influences oscillation frequency. When using a crystal that is manufactured for a
L
different load capacitance, the circuit will oscillate at a slightly different frequency
(depending on the quality of the crystal) compared to the specified one. Therefore for an
accurate time reference it is advised to use the load capacitors as specified in
that belong to a specific C
this table are calculated from the internal parasitic capacitances and the C
from PCB and package are not taken into account.
Table 21.
Crystal load capacitance
C
L
11 pF
13 pF
15 pF
LPC2420_60
Product data sheet
Recommended values for C
X1
components parameters): high frequency mode
Crystal load
capacitance C
OSC
10 pF
20 pF
10 pF
20 pF
LPC2xxx
RTCX1
RTCX2
32 kHz XTAL
C X2
C X1
crystal model used for C
/C
X1
X2
gives the crystal parameters that should be used. C
. The value of external capacitances C
L
Recommended values for the RTC external 32 kHz oscillator C
Maximum crystal series
resistance R
S
< 100 k
< 100 k
< 100 k
All information provided in this document is subject to legal disclaimers.
Rev. 6.1 — 22 September 2011
LPC2420/2460
Flashless 16-bit/32-bit microcontroller
/C
in oscillation mode (crystal and external
X2
Maximum crystal
External load
series resistance R
capacitors C
L
S
< 180 
18 pF, 18 pF
< 100 
39 pF, 39 pF
< 160 
18 pF, 18 pF
< 80 
39 pF, 39 pF
L
=
C L
R S
002aaf495
evaluation
Figure
31. Since the feedback resistance is
and C
need to be connected
X1
X2
is the typical load
L
and C
X1
External load capacitors C
18 pF, 18 pF
22 pF, 22 pF
27 pF, 27 pF
, C
X1
X2
C P
Table 21
specified in
X2
. Parasitics
L
/C
components
X1
X2
/C
X1
X2
© NXP B.V. 2011. All rights reserved.
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