LPC1313 datasheet(47/53 Pages) NXP

47 / 53 page

LPC1311_13_42_43_1

Product data sheet

Rev. 01 — 11 December 2009

47 of 53

NXP Semiconductors

LPC1311/13/42/43

32-bit ARM Cortex-M3 microcontroller

11.3 XTAL Printed-Circuit Board (PCB) layout guidelines

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 Cx1,Cx2, and Cx3 in 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 Cx1 and Cx2 should be chosen smaller

accordingly to the increase in parasitics of the PCB layout.

11.4 Standard I/O pad conﬁguration

Figure 29 shows the possible pin modes for standard I/O pins. The pull-up and pull-down

resistors (Rpu and Rpd) can be enabled or disabled. The default value for each standard

port pin is input with Rpu enabled. For details on pin modes and hysteresis control, see the

LPC13xx user manual.

Fig 28. Slave mode operation of the on-chip oscillator

LPC1xxx

XTALIN

100 pF

002aae788

Fig 29. Standard I/O pad conﬁguration

VDD(IO)

VSS

Rpd

Rpu

enable

output

input

002aae828

hysteresis

control

LPC1313 Datasheet(PDF) 47 Page - NXP Semiconductors