PIC18F44J10-ESLASHML datasheet(238/358 Pages) MICROCHIP

238 / 358 page

PIC18F45J10 FAMILY

DS39682C-page 236

Preliminary

20.3

On-Chip Voltage Regulator

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.

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

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.

Note:

The on-chip voltage regulator is only

available in parts designated with an “F”,

such as PIC18F45J10.

Note:

In parts designated with an “LF”, such as

PIC18LF45J10, VDDCORE must never

exceed VDD.

VDD

VDDCORE/VCAP

VSS

PIC18LFXXJ10

3.3V

2.5V

VDD

VDDCORE/VCAP

VSS

PIC18FXXJ10

3.3V

PIC18FXXJ10 Devices (Regulator Enabled):

VDD

VDDCORE/VCAP

VSS

PIC18LFXXJ10

2.5V

PIC18LFXXJ10 Devices (Regulator Disabled):

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