PIC18F23K20-E/MLQTP MICROCHIP [Microchip Technology], PIC18F23K20-E/MLQTP Datasheet - Page 287

• Manufacturer Part Number: PIC18F23K20-E/MLQTP
• Description: 28/40/44-Pin Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

22.2
The following steps are needed to set up the HLVD
module:
1.
2.
3.
4.
5.
22.3
When the module is enabled, the HLVD comparator
and voltage divider are enabled and will consume static
current. The total current consumption, when enabled,
is specified in electrical specification parameter D022B.
FIGURE 22-2:
© 2007 Microchip Technology Inc.
Write the value to the HLVDL<3:0> bits that
selects the desired HLVD trip point.
Set the VDIRMAG bit to detect high voltage
(VDIRMAG = 1) or low voltage (VDIRMAG = 0).
Enable the HLVD module by setting the
HLVDEN bit.
Clear the HLVD interrupt flag bit of the PIR2
register, which may have been set from a
previous interrupt.
Enable the HLVD interrupt if interrupts are
desired by setting the HLVDIE bit of the PIE2
register, and the GIE and PEIE bits of the
INTCON register. An interrupt will not be gener-
ated until the IRVST bit is set.
CASE 1:
CASE 2:
Enable HLVD
Enable HLVD
HLVD Setup
Current Consumption
HLVDIF
HLVDIF
IRVST
IRVST
V
V
DD
DD
LOW-VOLTAGE DETECT OPERATION (VDIRMAG =
Internal Reference is stable
Advance Information
Internal Reference is stable
T
T
IVRST
IVRST
HLVDIF may not be set
HLVDIF cleared by software,
HLVDIF remains set since HLVD condition still exists
Depending on the application, the HLVD module does
not need to be operating constantly. To decrease the
current requirements, the HLVD circuitry may only
need to be enabled for short periods where the voltage
is checked. After doing the check, the HLVD module
may be disabled.
22.4
The internal reference voltage of the HLVD module,
specified in electrical specification parameter D420,
may be used by other internal circuitry, such as the
Programmable Brown-out Reset. If the HLVD or other
circuits using the voltage reference are disabled to
lower the device’s current consumption, the reference
voltage circuit will require time to become stable before
a low or high-voltage condition can be reliably
detected. This start-up time, T
is independent of device clock speed. It is specified in
electrical specification parameter 36.
The HLVD interrupt flag is not enabled until T
expired and a stable reference voltage is reached. For
this reason, brief excursions beyond the set point may
not be detected during this interval. Refer to Figure 22-2
or Figure 22-3.
PIC18F2XK20/4XK20
HLVD Start-up Time
HLVDIF cleared by software
0
)
HLVDIF cleared by software
IRVST
V
V
DS41303B-page 285
, is an interval that
HLVD
HLVD
IRVST
has