Datasheet

LPC408X_7X All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 3.1 — 1 September 2014 114 of 138
NXP Semiconductors
LPC408x/7x
32-bit ARM Cortex-M4 microcontroller
13.2 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 39. USB device port configuration: port 1 host and port 2 device
USB_UP_LED1
USB_D+1
USB_D-1
USB_PWRD1
15 kΩ 15 kΩ
LPC408x/7x
USB-A
connector
USB-B
connector
33 Ω
33 Ω
33 Ω
33 Ω
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V
DD
USB_UP_LED2
USB_CONNECT2
V
DD
V
DD
USB_OVRCR1
USB_PPWR1
LM3526-L
ENA
IN
5 V
FLAGA
OUTA
V
DD
D+
D-
D+
D-
V
BUS
USB_D+2
USB_D-2
V
BUS
V
BUS
V
SSIO,
V
SSCORE
V
SSIO,
V
SSCORE
Fig 40. Slave mode operation of the on-chip oscillator
LPC40xx
XTAL1
C
i
100 pF
C
g
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