PIC18F2221 MICROCHIP [Microchip Technology], PIC18F2221 Datasheet - Page 250

• Manufacturer Part Number: PIC18F2221
• Description: 28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F4321 FAMILY
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
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.
FIGURE 22-1:
DS39689E-page 248
HLVDIN
V
Operation
DD
Externally Generated
Trip Point
HLVDIN
HLVD MODULE BLOCK DIAGRAM (WITH EXTERNAL INPUT)
HLVDEN
BOREN
V
DD
Preliminary
HLVDL3:HLVDL0
The trip point voltage is software programmable to
any one of 16 values. The trip point is selected
by
(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.
programming
Internal Voltage
Reference
HLVDEN
HLVDCON
Register
the
© 2007 Microchip Technology Inc.
VDIRMAG
HLVDL3:HLVDL0
HLVDIF
Set
bits