PIC18F44J50-I/SPSQTP View Datasheet(PDF) - Microchip Technology

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Description

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PIC18F44J50-I/SPSQTP

28/44-Pin, Low-Power, High-Performance USB Microcontrollers with nanoWatt XLP Technology

Microchip Technology 

PIC18F46J50 FAMILY

24.1 Configuring the Comparator

Voltage Reference

The comparator voltage reference module is controlled

through the CVRCON register (Register 24-1). 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 CVREF Selection bits

(CVR<3:0>), with one range offering finer resolution.

The equations used to calculate the output of the

comparator voltage reference are as follows:

EQUATION 24-1: CALCULATING OUTPUT

OF THE COMPARATOR

VOLTAGE REFERENCE

When CVRR = 1:

CVREF = ((CVR<3:0>)/24) x (VDD)

When CVRR = 0:

CVREF = (VDD/4) + ((CVR<3:0>)/32) x (VDD)

The settling time of the comparator voltage reference

must be considered when changing the CVREF

output (see Table 30-3 in Section 30.0 “Electrical

Characteristics”).

REGISTER 24-1: CVRCON: COMPARATOR VOLTAGE REFERENCE CONTROL REGISTER

(BANKED F53h)

R/W-0

CVREN

bit 7

R/W-0

CVROE(1)

R/W-0

CVRR

R/W-0

r

R/W-0

CVR3

R/W-0

CVR2

R/W-0

CVR1

R/W-0

CVR0

bit 0

Legend:

R = Readable bit

-n = Value at POR

r = Reserved bit

W = Writable bit

‘1’ = Bit is set

U = Unimplemented bit, read as ‘0’

‘0’ = Bit is cleared

x = Bit is unknown

bit 7

bit 6

bit 5

bit 4

bit 3-0

CVREN: Comparator Voltage Reference Enable bit

1 = CVREF circuit is powered on

0 = CVREF circuit is powered down

CVROE: Comparator VREF Output Enable bit(1)

1 = CVREF voltage level is also output on the RA2/AN2/VREF-/CVREF/C2INB pin

0 = CVREF voltage is disconnected from the RA2/AN2/VREF-/CVREF/C2INB pin

CVRR: Comparator VREF Range Selection bit

1 = 0 to 0.667 VDD, with VDD/24 step size (low range)

0 = 0.25 VDD to 0.75 VDD, with VDD/32 step size (high range)

Reserved: Always maintain as ‘0’

CVR<3:0>: Comparator VREF Value Selection bits (0  (CVR<3:0>)  15)

When CVRR = 1:

CVREF = ((CVR<3:0>)/24)  (VDD)

When CVRR = 0:

CVREF = (VDD/4) + ((CVR<3:0>)/32)  (VDD)

Note 1: CVROE overrides the TRIS bit setting.

DS39931D-page 392

 2011 Microchip Technology Inc.

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