PIC18F4685-ISLASHSP datasheet(269/484 Pages) MICROCHIP

269 / 484 page

Preliminary

DS39761B-page 267

PIC18F2682/2685/4682/4685

22.0

HIGH/LOW-VOLTAGE

DETECT (HLVD)

PIC18F2682/2685/4682/4685 devices have a High/

Low-Voltage

Detect

module

(HLVD).

This

programmable 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 22-1) 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 22-1.

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: High/Low-Voltage Detection Limit bits(1)

1111

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

1110

= 4.48V-4.69V

1101

= 4.23V-4.43V

1100

= 4.01V-4.20V

1011

= 3.81V-3.99V

1010

= 3.63V-3.80V

1001

= 3.46V-3.63V

1000

= 3.31V-3.47V

0111

= 3.05V-3.19V

0110

= 2.82V-2.95V

0101

= 2.72V-2.85V

0100

= 2.54V-2.66V

0011

= 2.38V-2.49V

0010

= 2.31V-2.42V

0001

= 2.18V-2.28V

0000

= 2.12V-2.22V

Note 1:

HLVDL3:HLVDL0 modes that result in a trip point below the valid operating voltage of the device are not tested.

PIC18F4685-I/SP Datasheet(PDF) 269 Page - Microchip Technology

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