Datasheet

© 2007-2012 Microchip Technology Inc. DS70291G-page 307
dsPIC33FJ32MC302/304, dsPIC33FJ64MCX02/X04 AND dsPIC33FJ128MCX02/X04
24.3 Comparator Voltage Reference
24.3.1 CONFIGURING THE COMPARATOR
VOLTAGE REFERENCE
The voltage reference module is controlled through the
CVRCON register (Register 24-2). The comparator
voltage reference provides two ranges of output
voltage, each with 16 distinct levels. The range to be
used is selected by the CVRR bit (CVRCON<5>). The
primary difference between the ranges is the size of the
steps selected by the CV
REF Selection bits
(CVR3:CVR0), with one range offering finer resolution.
The comparator reference supply voltage can come
from either V
DD and VSS, or the external VREF+ and
VREF-. The voltage source is selected by the CVRSS
bit (CVRCON<4>).
The settling time of the comparator voltage reference
must be considered when changing the CV
REF
output.
FIGURE 24-2: COMPARATOR VOLTAGE REFERENCE BLOCK DIAGRAM
16-to-1 MUX
8R
R
CVREN
CVRSS = 0
AV
DD
VREF+
CVRSS = 1
8R
CVRSS = 0
V
REF-
CVRSS = 1
R
R
R
R
R
R
16 Steps
CVRR
CVREF
CVR3 CVR2 CVR1 CVR0
CVRCON<3:0>
AV
SS
CVRSRC
CVROE (CVRCON<6>)
CVREFIN