PIC18F6390 Datasheet, PDF (253/412 Pages) Microchip Technology – 64/80-Pin Flash Microcontrollers with LCD Driver and nanoWatt Technology

PIC18F6390/6490/8390/8490
21.0 HIGH/LOW-VOLTAGE
DETECT (HLVD)
PIC18F6390/6490/8390/8490 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 21-1) 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 21-1.
REGISTER 21-1:
HLVDCON: HIGH/LOW-VOLTAGE DETECT CONTROL REGISTER
R/W-0
U-0
VDIRMAG —
R-0
R/W-0 R/W-0 R/W-1 R/W-0 R/W-1
IRVST 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:HLVDL0)
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 = 4.41V-4.87V
1101 = 4.11V-4.55V
1100 = 3.92V-4.34V
1011 = 3.72V-4.12V
1010 = 3.53V-3.91V
1001 = 3.43V-3.79V
1000 = 3.24V-3.58V
0111 = 2.95V-3.26V
0110 = 2.75V-3.03V
0101 = 2.64V-2.92V
0100 = 2.43V-2.69V
0011 = 2.35V-2.59V
0010 = 2.16V-2.38V
0001 = 1.96V-2.16V
0000 = Reserved
Note 1: HLVDL3:HLVDL0 modes that result in a trip point below the valid operating voltage
of the device are not tested.
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.
Preliminary
DS39629B-page 251