PIC32MX1XX_12 Datasheet, PDF (27/328 Pages) Microchip Technology – 32-bit Microcontrollers (up to 128 KB Flash and 32 KB SRAM) with Audio and Graphics Interfaces, USB, and Advanced Analog

PIC32MX1XX/2XX
2.0 GUIDELINES FOR GETTING
STARTED WITH 32-BIT MCUS
Note 1: This data sheet summarizes the features
of the PIC32MX1XX/2XX family of
devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to the related section of the
“PIC32 Family Reference Manual”, which
is available from the Microchip web site
(www.microchip.com/PIC32).
2: Some registers and associated bits
described in this section may not be
available on all devices. Refer to
Section 4.0 “Memory Organization” in
this data sheet for device-specific register
and bit information.
2.1 Basic Connection Requirements
Getting started with the PIC32MX1XX/2XX family of
32-bit Microcontrollers (MCUs) requires attention to a
minimal set of device pin connections before proceed-
ing with development. The following is a list of pin
names, which must always be connected:
• All VDD and VSS pins (see 2.2 “Decoupling
Capacitors”)
• All AVDD and AVSS pins, even if the ADC module is
not used (see 2.2 “Decoupling Capacitors”)
• VCAP pin (see 2.3 “Capacitor on Internal Voltage
Regulator (VCAP)”)
• MCLR pin (see 2.4 “Master Clear (MCLR) Pin”)
• PGECx/PGEDx pins, used for In-Circuit Serial
Programming (ICSP™) and debugging purposes
• (see 2.5 “ICSP Pins”)
• OSC1 and OSC2 pins, when external oscillator
source is used (see 2.7 “External Oscillator Pins”)
The following pin may be required, as well:
• VREF+/VREF- pins – used when external voltage
reference for the ADC module is implemented.
Note:
The AVDD and AVSS pins must be
connected, regardless of ADC use and
the ADC voltage reference source.
2.2 Decoupling Capacitors
The use of decoupling capacitors on power supply
pins, such as VDD, VSS, AVDD and AVSS is required.
See Figure 2-1.
Consider the following criteria when using decoupling
capacitors:
• Value and type of capacitor: A value of 0.1 µF
(100 nF), 10-20V is recommended. The capacitor
should be a low Equivalent Series Resistance (low-
ESR) capacitor and have resonance frequency in
the range of 20 MHz and higher. It is further
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 that the
capacitors be placed 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 par-
allel 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 implement-
ing 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 decou-
pling 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.
FIGURE 2-1:
RECOMMENDED
MINIMUM CONNECTION
VDD
R
R1
MCLR
CEFC
0.1 µF
Ceramic
CBP
C
VSS
PIC32
VUSB3V3⁽¹⁾
VDD
VDD
0.1 µF
Ceramic
CBP
10
0.1 µF
Ceramic
CBP
VSS
0.1 µF
Ceramic
CBP
0.1 µF
Ceramic
CBP
Note 1: If the USB module is not used, this pin must be
connected to VDD.
2.2.1 BULK CAPACITORS
The use of a bulk capacitor is recommended to improve
power supply stability. Typical values range from 4.7 µF
to 47 µF. This capacitor should be located as close to
the device as possible.
 2011-2012 Microchip Technology Inc.
Preliminary
DS61168E-page 27