NXP Semiconductors LPC1768 - Pin Description

UM10360 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
User manual Rev. 3 — 19 December 2013 576 of 841
NXP Semiconductors
UM10360
Chapter 29: LPC176x/5x Analog-to-Digital Converter (ADC)
29.4 Pin description
Table 529 gives a brief summary of each of ADC related pins.
Table 529. ADC pin description
Pin Type Description
AD0.7 to AD0.0 Input Analog Inputs. The ADC cell can measure the voltage on any of these input signals.
Digital signals are disconnected from the ADC input pins when the ADC function is
selected on that pin in the Pin Select register.
Warning: if the ADC is used, signal levels on analog input pins must not be above the
level of V
DDA
at any time. Otherwise, A/D converter readings will be invalid. If the A/D
converter is not used in an application then the pins associated with A/D inputs can be
used as 5 V tolerant digital IO pins.
V
REFP
, V
REFN
Reference Voltage References. These pins provide a voltage reference level for the ADC and
DAC. Note: V
REFP
should be tied to VDD(3V3) and V
REFN
should be tied to V
SS
if
the ADC and DAC are not used.
V
DDA
, V
SSA
Power Analog Power and Ground. These should typically be the same voltages as V
DD
and
V
SS
, but should be isolated to minimize noise and error. Note: VDDA should be tied
to VDD(3V3) and VSSA should be tied to VSS if the ADC and DAC are not used.