LPC1754 NXP [NXP Semiconductors], LPC1754 Datasheet - Page 58

• Manufacturer Part Number: LPC1754
• Description: 32-bit ARM Cortex-M3 MCU; up to 512 kB flash and 64 kB SRAM with Ethernet, USB 2.0 Host/Device/OTG, CAN
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
LPC1759_58_56_54_52_51_4
Product data sheet
Fig 27. LPC1759/58/56/54/52/51 USB device port configuration
14.2 XTAL1 input
14.3 XTAL and RTCX Printed Circuit Board (PCB) layout guidelines
LPC17xx
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 LPC17xx
User manual.
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
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
accordingly to the increase in parasitics of the PCB layout.
Fig 28. Slave mode operation of the on-chip oscillator
i
= 100 pF. To limit the input voltage to the specified range, choose an additional
USB_UP_LED
USB_CONNECT
USB_D+
USB_D−
V
BUS
33 Ω
33 Ω
g
Rev. 04 — 26 January 2010
V
which attenuates the input voltage by a factor C
DD
V
DD
XTAL1
LPC1759/58/56/54/52/51
LPC1xxx
C i
100 pF
x1
and C
002aae835
32-bit ARM Cortex-M3 microcontroller
C g
x2
should be chosen smaller
V
SS
V
BUS
D+
D−
x1
, C
x2
, and C
USB-B
connector
002aad943
i
© NXP B.V. 2010. All rights reserved.
/ (C
i
+ C
x3
in case of
g
). In
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