PIC18F47J53 Datasheet, PDF (421/586 Pages) Microchip Technology – 28/44-Pin, High-Performance USB Microcontrollers with nanoWatt XLP Technology

PIC18F47J53 FAMILY
26.2 HLVD Setup
To set up the HLVD module:
1. Disable the module by clearing the HLVDEN bit
(HLVDCON<4>).
2. Write the value to the HLVDL<3:0> bits that
select the desired HLVD trip point.
3. Set the VDIRMAG bit to detect one of the
following:
• High voltage (VDIRMAG = 1)
• Low voltage (VDIRMAG = 0)
4. Enable the HLVD module by setting the
HLVDEN bit.
5. Clear the HLVD Interrupt Flag, HLVDIF
(PIR2<2>), which may have been set from a
previous interrupt.
6. If interrupts are desired, enable the HLVD inter-
rupt by setting the HLVDIE and GIE/GIEH bits
(PIE2<2> and INTCON<7>).
An interrupt will not be generated until the
IRVST bit is set.
26.3 Current Consumption
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 (IHLVD) (Section 31.2 “DC Char-
acteristics: Power-Down and Supply Current
PIC18F47J53 Family (Industrial)”).
Depending on the application, the HLVD module does
not need to operate 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.
26.4 HLVD Start-up Time
The internal reference voltage of the HLVD module,
specified in electrical specification parameter D420
(see Table 31-8 in Section 31.0 “Electrical Charac-
teristics”), may be used by other internal circuitry,
such as the Programmable Brown-out Reset (BOR).
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, TIRVST, is an
interval that is independent of device clock speed. It is
specified in electrical specification, parameter 36
(Table 31-14).
The HLVD interrupt flag is not enabled until TIRVST has
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 26-2
or Figure 26-3.
 2010 Microchip Technology Inc.
Preliminary
DS39964B-page 421