PIC18F4550ESOSQTP datasheet(281/430 Pages) MICROCHIP

281 / 430 page

Preliminary

DS39632D-page 279

PIC18F2455/2550/4455/4550

24.0

HIGH/LOW-VOLTAGE DETECT

(HLVD)

PIC18F2455/2550/4455/4550

devices

have

High/Low-Voltage Detect module (HLVD). This is a pro-

grammable circuit that allows the user to specify both a

device voltage trip point and the direction of change

from that point. If the device experiences an excursion

past the trip point in that direction, an interrupt flag is

set. If the interrupt is enabled, the program execution

will branch to the interrupt vector address and the

software can then respond to the interrupt.

The

High/Low-Voltage

Detect

Control

(Register 24-1) completely controls the operation of the

HLVD module. This allows the circuitry to be “turned

off” by the user under software control which minimizes

the current consumption for the device.

The block diagram for the HLVD module is shown in

Figure 24-1.

HLVDCON: HIGH/LOW-VOLTAGE DETECT CONTROL REGISTER

R/W-0

U-0

R-0

R/W-0

R/W-1

R/W-0

R/W-1

VDIRMAG

—

IRVST

HLVDEN

HLVDL3(1)

HLVDL2(1)

HLVDL1(1)

HLVDL0(1)

bit 7

bit 0

Legend:

R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7

VDIRMAG: Voltage Direction Magnitude Select bit

= Event occurs when voltage equals or exceeds trip point (HLVDL3:HLDVL0)

= Event occurs when voltage equals or falls below trip point (HLVDL3:HLVDL0)

bit 6

Unimplemented: Read as ‘0’

bit 5

IRVST: Internal Reference Voltage Stable Flag bit

= Indicates that the voltage detect logic will generate the interrupt flag at the specified voltage range

= Indicates that the voltage detect logic will not generate the interrupt flag at the specified voltage

range and the HLVD interrupt should not be enabled

bit 4

HLVDEN: High/Low-Voltage Detect Power Enable bit

= HLVD enabled

= HLVD disabled

bit 3-0

HLVDL3:HLVDL0: Voltage Detection Limit bits(1)

1111

= External analog input is used (input comes from the HLVDIN pin)

1110

= Maximum setting

0000

= Minimum setting

Note 1:

See Table 28-6 in Section 28.0 “Electrical Characteristics” for specifications.

PIC18F4550ESOSQTP Datasheet(PDF) 281 Page - Microchip Technology

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