PIC32MX440F256H-80I Datasheet, PDF (555/646 Pages) Microchip Technology – 64/100-Pin General Purpose and USB 32-Bit Flash Microcontrollers

PIC32MX3XX/4XX
25.2.1 CVREF OUTPUT CONSIDERATIONS
The full range of voltage reference cannot be realized
due to the construction of the module. The transistors
on the top and bottom of the resistor ladder network
(Figure 25-1) keep the voltage reference from
approaching the reference source rails. The voltage
reference is derived from the reference source; there-
fore, the voltage reference output changes with
fluctuations in that source. Refer to the product data
sheet for the electrical specifications. Table 25-3
contains the typical output impedances for the CVREF
module.
TABLE 25-3: TYPICAL CVREF OUTPUT IMPEDANCE IN OHMS
CVR<3:0>
Voltage Reference
CVRR = 0 (CVRCON <5>)
CVRR = 1 (CVRCON <5>
0
12k
1
13k
2
13.8k
3
14.4k
4
15k
5
15.4k
6
15.8k
7
15.9k
8
16k
9
15.9k
10
15.8k
11
15.4k
12
15k
13
14.4k
14
13.8k
15
12.9k
500
1.9k
3.7k
5.3k
6.7k
7.9k
9k
9.9k
10.7k
11.3k
11.7k
11.9k
12k
11.9k
11.7k
11.3k
25.2.2 INITIALIZATION
This initialization sequence, shown in Example 25-1,
configures the CVREF module for: module enabled, out-
put enabled, high range, and set output for maximum
(2.37V).
EXAMPLE 25-1: VOLTAGE REFERENCE CONFIGURATION
CVRCON = 0x804F;
//Initialize Voltage Reference Module
//enable module, enable output, set
// range to high, set output to maximum
© 2008 Microchip Technology Inc.
Preliminary
DS61143E-page 553