
UM10800
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© NXP Semiconductors N.V. 2016. All rights reserved.
User manual
Rev. 1.2 — 5 October 2016
354 of 487
NXP Semiconductors
UM10800
Chapter 22: LPC82x Analog comparator
22.4 Pin description
The analog comparator reference voltage, the inputs, and the output are assigned to
external pins through the switch matrix. You can assign the analog comparator output to
any pin on the package that is not a supply or ground pin. The comparator inputs and the
reference voltage are fixed-pin functions that must be enabled through the switch matrix
and can only be assigned to special pins on the package.
See
Section 7.3.1 “Connect an internal signal to a package pin”
to assign the analog
comparator output to any pin on the LPC82x package.
22.5 General description
The analog comparator can compare voltage levels on external pins and internal voltages.
The comparator has seven inputs multiplexed separately to its positive and negative
inputs. The multiplexers are controlled by the comparator register CTL (see
and
Input 0 of the multiplexer is the programmable voltage ladder output.
Inputs 1 to 4 connect the external inputs ACMP_I[4:1].
Input 5 of the multiplexer connects the internal reference voltage input.
Input 6 of the multiplexer connects the ADC channel 0 input.
Input 7 is tied to ground.
Table 294. Analog comparator pin description
Function
Type Pin
Description
SWM register
Reference
ACMP_I1
I
PIO0_0
Comparator input 1
PINENABLE0
ACMP_I2
I
PIO0_1
Comparator input 2
PINENABLE0
ACMP_I3
I
PIO0_14
Comparator input 3
PINENABLE0
ACMP_I4
I
PIO0_23
Comparator input 4
PINENABLE0
ACMP_O
O
any
Comparator output
PINASSIGN8
VDDCMP I
PIO0_6
External reference voltage source for
32-stage Voltage Ladder.
PINENABLE0