Datasheet

 2010 Microchip Technology Inc. Preliminary DS39974A-page 391
PIC18F47J13 FAMILY
25.0 HIGH/LOW VOLTAGE DETECT
(HLVD)
The High/Low-Voltage Detect (HLVD) module can be
used to monitor the absolute voltage on V
DD or the
HLVDIN pin. This is a programmable circuit that allows
the user to specify both a device voltage trip point and
the direction of change from that point.
If the module detects 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 inter-
rupt vector address and the software can then respond
to the interrupt.
The High/Low-Voltage Detect Control register
(Register 25-1) 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.
Figure 25-1 provides a block diagram for the HLVD
module.
REGISTER 25-1: HLVDCON: HIGH/LOW-VOLTAGE DETECT CONTROL REGISTER (ACCESS F85h)
R/W-0 R-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
VDIRMAG BGVST 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
1 = Event occurs when the voltage equals or exceeds the trip point (HLVDL<3:0>)
0 = Event occurs when the voltage equals or falls below the trip point (HLVDL<3:0>)
bit 6 BGVST: Band Gap Reference Voltages Stable Status Flag bit
1 = Indicates internal band gap voltage references is stable
0 = Indicates internal band gap voltage reference is not stable
bit 5 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
bit 4 HLVDEN: High/Low-Voltage Detect Power Enable bit
1 = HLVD is enabled
0 = HLVD is disabled
bit 3-0 HLVDL<3:0>: 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 30-8 in Section 30.0 “Electrical Characteristics” for specifications.