PIC18F45J10 Datasheet, PDF (238/358 Pages) Microchip Technology – 28/40/44-Pin High-Performance RISC Microcontrollers with nanoWatt Technology

PIC18F45J10 FAMILY
20.3 On-Chip Voltage Regulator
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 can
be powered from an external source that is separate
from VDD, or it can be powered from an on-chip regula-
tor which derives power from VDD. Both sources use
the common VDDCORE/VCAP pin.
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 20-2.
Note:
In parts designated with an “LF”, such as
PIC18LF45J10, VDDCORE must never
exceed VDD.
The specifications for core voltage and capacitance are
listed in Section 23.4 “AC (Timing) Characteristics”.
FIGURE 20-2:
CONNECTIONS FOR THE
ON-CHIP REGULATOR
PIC18FXXJ10 Devices (Regulator Enabled):
3.3V
PIC18FXXJ10
VDD
VDDCORE/VCAP
CF
VSS
20.3.1 ON-CHIP REGULATOR AND BOR
PIC18F45J10 family devices (designated with an “F”
part number) 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>).
The operation of the BOR is described in more detail in
Section 4.4
“Brown-out
Reset
(BOR)
(PIC18F2X1X/4X1X Devices Only)” and Section 4.4.1
“Detecting BOR”. The brown-out voltage levels are
specific in Section 23.1 “DC Characteristics”.
20.3.2 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.
PIC18LFXXJ10 Devices (Regulator Disabled):
2.5V
PIC18LFXXJ10
VDD
VDDCORE/VCAP
VSS
OR
2.5V
3.3V
PIC18LFXXJ10
VDD
VDDCORE/VCAP
VSS
DS39682C-page 236
Preliminary
© 2007 Microchip Technology Inc.