LPC2368 NXP Semiconductors, LPC2368 Datasheet - Page 51

• Manufacturer Part Number: LPC2368
• Description: Single-chip 16-bit/32-bit microcontrollers/ up to 512 kB flash
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC2364_65_66_67_68_6
Product data sheet
Fig 17. LPC2364/66/68 USB interface on a bus-powered device
13.2 XTAL1 input
13.3 XTAL and RTC Printed-Circuit Board (PCB) layout guidelines
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
capacitor to ground C
slave mode, a minimum of 200 mV (RMS) is needed. For more details see the LPC24xx
User manual UM10237.
The crystal should be connected on the PCB as close as possible to the oscillator input
and output pins of the chip. Take care that the load capacitors C
case of third overtone crystal usage, have a common ground plane. The external
components must also be connected to the ground plain. Loops must be made as small
as possible, in order to keep the noise coupled in via the PCB as small as possible. Also
parasitics should stay as small as possible. Values of C
smaller accordingly to the increase in parasitics of the PCB layout.
Fig 18. Slave mode operation of the on-chip oscillator
i
= 100 pF. To limit the input voltage to the specified range, choose an additional
LPC23XX
V
USB_UP_LED
V
USB_D+
USB_D−
V
g
Rev. 06 — 1 February 2010
DD(3V3)
BUS
SS
which attenuates the input voltage by a factor C
R S = 33 Ω
R S = 33 Ω
R2
R1
1.5 kΩ
XTAL1
C i
100 pF
LPC2xxx
LPC2364/65/66/67/68
Single-chip 16-bit/32-bit microcontrollers
002aae718
C g
002aac579
x1
and C
USB-B
connector
x2
x1
should be chosen
and C
www.DataSheet4U.com
i
© NXP B.V. 2010. All rights reserved.
/ (C
x2
, and C
i
+ C
g
). In
x3
51 of 59
in