Datasheet

© 2009 Microchip Technology Inc. DS39689F-page 25
PIC18F2221/2321/4221/4321 FAMILY
2.0 GUIDELINES FOR GETTING
STARTED WITH PIC18F
MICROCONTROLLERS
2.1 Basic Connection Requirements
Getting started with the PIC18F2221/2321/4221/4321
family family of 8-bit microcontrollers requires attention
to a minimal set of device pin connections before
proceeding with development.
The following pins must always be connected:
•All V
DD and VSS pins
(see Section 2.2 “Power Supply Pins”)
•All AV
DD and AVSS pins, regardless of whether or
not the analog device features are used
(see Section 2.2 “Power Supply Pins”)
•M
CLR pin
(see Section 2.3 “Master Clear (MCLR) Pin”)
These pins must also be connected if they are being
used in the end application:
• PGC/PGD pins used for In-Circuit Serial
Programming™ (ICSP™) and debugging purposes
(see Section 2.4 “ICSP Pins”)
• OSCI and OSCO pins when an external oscillator
source is used
(see Section 2.5 “External Oscillator Pins”)
Additionally, the following pins may be required:
•V
REF+/VREF- pins used when external voltage
reference for analog modules is implemented
The minimum mandatory connections are shown in
Figure 2-1.
FIGURE 2-1: RECOMMENDED
MINIMUM CONNECTIONS
Note: The AVDD and AVSS pins must always be
connected, regardless of whether any of
the analog modules are being used.
PIC18FXXXX
VDD
VSS
VDD
VSS
VSS
VDD
AVDD AVSS VDD VSS
C1
R1
V
DD
MCLR
R2
C2
(1)
C3
(1)
C4
(1)
C5
(1)
C6
(1)
Key (all values are recommendations):
C1 through C6: 0.1 μF, 20V ceramic
C7: 10 μF, 16V tantalum or ceramic
R1: 10 kΩ
R2: 100Ω to 470Ω
Note 1: The example shown is for a PIC18F device
with five V
DD/VSS and AVDD/AVSS pairs.
Other devices may have more or less pairs;
adjust the number of decoupling capacitors
appropriately.