Datasheet

© 2009 Microchip Technology Inc. DS70175H-page 15
PIC24HJXXXGPX06/X08/X10
2.0 GUIDELINES FOR GETTING
STARTED WITH 16-BIT
MICROCONTROLLERS
2.1 Basic Connection Requirements
Getting started with the PIC24HJXXXGPX06/X08/X10
family of 16-bit Microcontrollers (MCUs) requires
attention to a minimal set of device pin connections
before proceeding with development. The following is a
list of pin names, which must always be connected:
• All V
DD and VSS pins
(see Section 2.2 “Decoupling Capacitors”)
• All AV
DD and AVSS pins (regardless if ADC module
is not used)
(see Section 2.2 “Decoupling Capacitors”)
•V
CAP/VDDCORE
(see Section 2.3 “Capacitor on Internal Voltage
Regulator (VCAP/VDDCORE)”)
•MCLR
pin
(see Section 2.4 “Master Clear (MCLR) Pin”)
• PGECx/PGEDx pins used for In-Circuit Serial
Programming™ (ICSP™) and debugging purposes
(see Section 2.5 “ICSP Pins”)
• OSC1 and OSC2 pins when external oscillator
source is used
(see Section 2.6 “External Oscillator Pins”)
Additionally, the following pins may be required:
•V
REF+/VREF- pins used when external voltage
reference for ADC module is implemented
2.2 Decoupling Capacitors
The use of decoupling capacitors on every pair of
power supply pins, such as V
DD, VSS, AVDD and
AVSS is required.
Consider the following criteria when using decoupling
capacitors:
• Value and type of capacitor: Recommendation
of 0.1 µF (100 nF), 10-20V. This capacitor should
be a low-ESR and have resonance frequency in
the range of 20 MHz and higher. It is
recommended that ceramic capacitors be used.
• Placement on the printed circuit board: The
decoupling capacitors should be placed as close
to the pins as possible. It is recommended to
place the capacitors on the same side of the
board as the device. If space is constricted, the
capacitor can be placed on another layer on the
PCB using a via; however, ensure that the trace
length from the pin to the capacitor is within
one-quarter inch (6 mm) in length.
• Handling high frequency noise: If the board is
experiencing high frequency noise, upward of
tens of MHz, add a second ceramic-type capacitor
in parallel to the above described decoupling
capacitor. The value of the second capacitor can
be in the range of 0.01 µF to 0.001 µF. Place this
second capacitor next to the primary decoupling
capacitor. In high-speed circuit designs, consider
implementing a decade pair of capacitances as
close to the power and ground pins as possible.
For example, 0.1 µF in parallel with 0.001 µF.
• Maximizing performance: On the board layout
from the power supply circuit, run the power and
return traces to the decoupling capacitors first,
and then to the device pins. This ensures that the
decoupling capacitors are first in the power chain.
Equally important is to keep the trace length
between the capacitor and the power pins to a
minimum thereby reducing PCB track inductance.
Note: This data sheet summarizes the features
of the PIC24HJXXXGPX06/X08/X10
family of devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to the “PIC24H Family
Reference Manual”, which is available
from the Microchip website
(www.microchip.com).
Note: The AVDD and AVSS pins must be
connected independent of the ADC
voltage reference source.