PIC18LF4420T-I/SO View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC18LF4420T-I/SO

28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

Microchip Technology 

PIC18F2420/2520/4420/4520

22.0 HIGH/LOW-VOLTAGE

DETECT (HLVD)

PIC18F2420/2520/4420/4520 devices have a

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

(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.

REGISTER 22-1:

HLVDCON REGISTER (HIGH/LOW-VOLTAGE DETECT CONTROL)

R/W-0

U-0

VDIRMAG —

R-0

IRVST

R/W-0 R/W-0 R/W-1 R/W-0 R/W-1

HLVDEN HLVDL3(1) HLVDL2(1) HLVDL1(1) HLVDL0(1)

bit 7

bit 0

bit 7

bit 6

bit 5

bit 4

bit 3-0

VDIRMAG: Voltage Direction Magnitude Select bit

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

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

Unimplemented: Read as ‘0’

IRVST: Internal Reference Voltage Stable Flag bit

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

range

0 = 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

HLVDEN: High/Low-Voltage Detect Power Enable bit

1 = HLVD enabled

0 = HLVD disabled

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 26-4 for specifications.

Legend:

R = Readable bit

-n = Value at POR

W = Writable bit

‘1’ = Bit is set

U = Unimplemented bit, read as ‘0’

‘0’ = Bit is cleared x = Bit is unknown

 2004 Microchip Technology Inc.

DS39631A-page 243

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