PIC18F2480 MICROCHIP [Microchip Technology], PIC18F2480 Datasheet - Page 270

• Manufacturer Part Number: PIC18F2480
• Description: 28/40/44-Pin Enhanced Flash Microcontrollers with ECAN Technology, 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F2480/2580/4480/4580
The module is enabled by setting the HLVDEN bit.
Each time that the HLVD module is enabled, the
circuitry requires some time to stabilize. The IRVST bit
is a read-only bit and is used to indicate when the circuit
is stable. The module can only generate an interrupt
after the circuit is stable and IRVST is set.
The VDIRMAG bit determines the overall operation of
the module. When VDIRMAG is cleared, the module
monitors for drops in V
point. When the bit is set, the module monitors for rises
in V
22.1
When the HLVD module is enabled, a comparator uses
an internally generated reference voltage as the set
point. The set point is compared with the trip point
where each node in the resistor divider represents a
trip point voltage. The “trip point” voltage is the voltage
level at which the device detects a high or low-voltage
FIGURE 22-1:
DS39637A-page 268
HLVDIN
DD
above the set point.
V
Operation
DD
Externally Generated
Trip Point
HLVDIN
HLVD MODULE BLOCK DIAGRAM (WITH EXTERNAL INPUT)
DD
below a predetermined set
HLVDEN
BOREN
V
DD
Preliminary
HLVDL3:HLVDL0
event, depending on the configuration of the module.
When the supply voltage is equal to the trip point, the
voltage tapped off of the resistor array is equal to the
internal reference voltage generated by the voltage
reference module. The comparator then generates an
interrupt signal by setting the HLVDIF bit.
The trip point voltage is software programmable to any
one of 16 values. The trip point is selected by
programming
(HLVDCON<3:0>).
The HLVD module has an additional feature that allows
the user to supply the trip voltage to the module from an
external source. This mode is enabled when bits
HLVDL3:HLVDL0 are set to ‘1111’. In this state, the
comparator input is multiplexed from the external input
pin, HLVDIN. This gives users flexibility because it
allows them to configure the High/Low-Voltage Detect
interrupt to occur at any voltage in the valid operating
range.
Internal Voltage
Reference
HLVDEN
HLVDCON
the
Register
 2004 Microchip Technology Inc.
VDIRMAG
HLVDL3:HLVDL0
HLVDIF
Set
bits