PIC32MX440F256H-80I Datasheet, PDF (554/646 Pages) Microchip Technology – 64/100-Pin General Purpose and USB 32-Bit Flash Microcontrollers

PIC32MX3XX/4XX
25.2 Operation
The CVREF module is controlled through the CVRCON
register (Register 25-1). The CVREF 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 CVREF
Value Selection bits, CVR3:CVR0, with one range
offering finer resolution and the other offering a wider
range of output voltage. The typical output voltages are
listed in Table 25-2.
The equations used to calculate the CVREF output are
as follows:
If CVRR = 1:
Voltage
Reference = ((CVR3:CVR0)/24) x (CVRSRC)
If CVRR = 0:
Voltage
Reference = (CVRSRC/4) + ((CVR3:CVR0)/32)
x (CVRSRC)
The CVREF Source Voltage (CVRSRC) can come from
either VDD and VSS, or the external VREF+ and VREF-
pins that are multiplexed with I/O pins. The voltage
source is selected by the CVRSS bit (CVRCON<4>).
The voltage reference is output to the CVREF pin by set-
ting the CVROE (CVRCON<6>) bit; this will override
the corresponding TRIS bit setting.
The settling time of the CVREF must be considered
when changing the CVREF output (refer to the data
sheet for your device).
TABLE 25-2: TYPICAL VOLTAGE REFERENCE WITH CVRSRC = 3.3
CVR<3:0>
Voltage Reference
CVRR = 0 (CVRCON <5>)
CVRR = 1 (CVRCON <5>
0
0.83V
1
0.93V
2
1.03V
3
1.13V
4
1.24V
5
1.34V
6
1.44V
7
1.55V
8
1.65V
9
1.75V
10
1.86V
11
1.96V
12
2.06V
13
2.17V
14
2.27V
15
2.37V
0.00V
0.14V
0.28V
0.41V
0.55V
0.69V
0.83V
0.96V
1.10V
1.24V
1.38V
1.51V
1.65V
1.79V
1.93V
2.06V
DS61143E-page 552
Preliminary
© 2008 Microchip Technology Inc.