PIC18F45J10 FAMILY
21.3.1
ON-CHIP REGULATOR AND BOR
21.3 On-Chip Voltage Regulator
When the on-chip regulator is enabled, PIC18F45J10
family devices also have a simple brown-out capability.
If the voltage supplied to the regulator is inadequate to
maintain a regulated level, the regulator Reset circuitry
will generate a BOR Reset. This event is captured by
the BOR flag bit (RCON<0>).
Note:
The on-chip voltage regulator is only
available in parts designated with an “F”,
such as PIC18F45J10.
In parts designated “LF”, the microcontroller core is
powered from an external source that is separate from
VDD. This voltage is supplied on the VDDCORE pin.
The operation of the BOR is described in more detail in
Section 5.4
(PIC18F2XJ10/4XJ10
Section 5.4.1 “Detecting BOR”. The brown-out voltage
levels are specific in Section 23.1 “DC Characteristics:
Supply Voltage”.
“Brown-out
Devices
Reset
Only)”
(BOR)
In “F” devices, a low-ESR capacitor must be connected
to the VDDCORE/VCAP pin for proper device operation.
In parts designated with an “LF” part number (i.e.,
PIC18LF45J10), power to the core must be supplied on
VDDCORE/VCAP. It is always good design practice to
have sufficient capacitance on all supply pins.
Examples are shown in Figure 21-2.
and
21.3.2
POWER-UP REQUIREMENTS
The on-chip regulator is designed to meet the power-up
requirements for the device. While powering up,
VDDCORE must never exceed VDD by 0.3 volts.
Note:
In parts designated with an “LF”, such as
PIC18LF45J10, VDDCORE must never
exceed VDD.
The specifications for core voltage and capacitance
are listed inTable 24-4 of Section 24.0 “Electrical
Characteristics”.
FIGURE 21-2:
CONNECTIONS FOR THE
ON-CHIP REGULATOR
PIC18FXXJ10 Devices (Regulator Enabled):
3.3V
PIC18FXXJ10
VDD
VDDCORE/VCAP
CEFC
VSS
PIC18LFXXJ10 Devices (Regulator Disabled):
2.5V
PIC18LFXXJ10
VDD
VDDCORE/VCAP
VSS
OR
3.3V
2.5V
PIC18LFXXJ10
VDD
VDDCORE/VCAP
VSS
© 2009 Microchip Technology Inc.
DS39682E-page 243
MICROCHIP [ MICROCHIP ]
