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LPC2460FET208,551

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P48P49-P51P52-P54P55-P57P58-P60P61-P63P64-P66P67-P69P70-P72P73-P75P76-P78P79-P81P82-P84P85-P87
LPC2420_60 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 6.2 — 16 October 2013 73 of 87
NXP Semiconductors
LPC2420/2460
Flashless 16-bit/32-bit microcontroller
14.3 Crystal oscillator XTAL input and component selection
The input voltage to the on-chip oscillators is limited to 1.8 V. If the oscillator is driven by a
clock in slave mode, it is recommended that the input be coupled through a capacitor with
C
i
= 100 pF. To limit the input voltage to the specified range, choose an additional
capacitor to ground C
g
which attenuates the input voltage by a factor C
i
/ (C
i
+ C
g
). In
slave mode, a minimum of 200 mV (RMS) is needed.
Fig 28. LPC2420/2460 USB OTG port configuration: USB port 1 host, USB port 2 host
USB_UP_LED1
USB_D+1
USB_D−1
USB_PWRD1
USB_PWRD2
15 kΩ
15 kΩ 15 kΩ
15 kΩ
LPC24XX
USB-A
connector
USB-A
connector
33 Ω
33 Ω
33 Ω
33 Ω
002aad596
V
DD
USB_UP_LED2
V
DD
USB_OVRCR1
USB_OVRCR2
USB_PPWR1
LM3526-L
ENA
ENB
IN
5 V
FLAGA
OUTA
OUTB
FLAGB
V
DD
V
DD
D+
D−
D+
D−
V
BUS
V
BUS
USB_PPWR2
USB_D+2
USB_D−2
V
SSIO,
V
SSCORE
V
SSIO,
V
SSCORE
Fig 29. Slave mode operation of the on-chip oscillator
LPC2xxx
XTAL1
C
i
100 pF
C
g
002aae718
LPC2420_60 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 6.2 — 16 October 2013 74 of 87
NXP Semiconductors
LPC2420/2460
Flashless 16-bit/32-bit microcontroller
In slave mode the input clock signal should be coupled by means of a capacitor of 100 pF
(Figure 29
), 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 XTAL2 pin in this configuration can be left unconnected.
External components and models used in oscillation mode are shown in Figure 30
and in
Table 19
and Table 20. 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 30 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. Oscillator modes and models: oscillation mode of operation and external crystal
model used for C
X1
/C
X2
evaluation
Table 19. 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 to 5 MHz 10 pF < 300 18 pF, 18 pF
20 pF < 300 39 pF, 39 pF
30 pF < 300 57 pF, 57 pF
5 MHz to 10 MHz 10 pF < 300 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
002aag469
LPC2xxx
XTAL1 XTAL2
C
X2
C
X1
XTAL
=
C
L
C
P
R
S
L
LPC2420_60 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 6.2 — 16 October 2013 75 of 87
NXP Semiconductors
LPC2420/2460
Flashless 16-bit/32-bit microcontroller
14.4 RTC 32 kHz oscillator component selection
The RTC external oscillator circuit is shown in Figure 31. Since the feedback resistance is
integrated on chip, only a crystal, the capacitances C
X1
and C
X2
need to be connected
externally to the microcontroller.
Table 21
gives the crystal parameters that should be used. C
L
is the typical load
capacitance of the crystal and is usually specified by the crystal manufacturer. The actual
C
L
influences oscillation frequency. When using a crystal that is manufactured for a
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 Table 21
that belong to a specific C
L
. The value of external capacitances C
X1
and C
X2
specified in
this table are calculated from the internal parasitic capacitances and the C
L
. Parasitics
from PCB and package are not taken into account.
Table 20. Recommended values for C
X1
/C
X2
in oscillation mode (crystal and external
components parameters): high 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
15 MHz to 20 MHz 10 pF < 180 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
Fig 31. RTC oscillator modes and models: oscillation mode of operation and external
crystal model used for C
X1
/C
X2
evaluation
Table 21. Recommended values for the RTC external 32 kHz oscillator C
X1
/C
X2
components
Crystal load capacitance
C
L
Maximum crystal series
resistance R
S
External load capacitors C
X1
/C
X2
11 pF < 100 k 18 pF, 18 pF
13 pF < 100 k 22 pF, 22 pF
15 pF < 100 k 27 pF, 27 pF
002aaf495
LPC2xxx
RTCX1 RTCX2
C
X2
C
X1
32 kHz XTAL
=
C
L
C
P
R
S
L
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P33P34-P36P37-P39P40-P42P43-P45P46-P48P49-P51P52-P54P55-P57P58-P60P61-P63P64-P66P67-P69P70-P72P73-P75P76-P78P79-P81P82-P84P85-P87

LPC2460FET208,551

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Buy LPC2460FET208,551
Manufacturer:
NXP Semiconductors
Description:
ARM Microcontrollers - MCU ARM7 USBHOST/ENET ROMLESS
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