PIC32MX3XX_1 Datasheet, PDF (32/208 Pages) Microchip Technology – High-Performance, General Purpose and USB 32-bit Flash Microcontrollers

PIC32MX3XX/4XX
FIGURE 2-1:
RECOMMENDED
MINIMUM CONNECTION
VDD
R
R1
MCLR
C
0.1 µF
Ceramic
CBP
VSS
VDD
10 Ω
CEFC
PIC32MX
0.1 µF
Ceramic
CBP
0.1 µF
Ceramic
CBP
VDD
VSS
0.1 µF
Ceramic
CBP
0.1 µF
Ceramic
CBP
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.
2.3 Capacitor on Internal Voltage
Regulator (VCAP/VDDCORE)
2.3.1 INTERNAL REGULATOR MODE
A low-ESR (< 1 Ohm) capacitor is required on the
VCAP/VDDCORE pin, which is used to stabilize the
internal voltage regulator output. The VCAP/VDDCORE
pin must not be connected to VDD, and must have a
CEFC capacitor, with at least a 6V rating, connected to
ground. The type can be ceramic or tantalum. Refer to
Section 29.0 “Electrical Characteristics” for
additional information on CEFC specifications. This
mode is enabled by connecting the ENVREG pin to
VDD.
2.3.2 EXTERNAL REGULATOR MODE
In this mode the core voltage is supplied externally
through the VDDCORE pin. A low-ESR capacitor of
10 µF is recommended on the VDDCORE pin. This mode
is enabled by grounding the ENVREG pin.
The placement of this capacitor should be close to the
VCAP/VDDCORE. It is recommended that the trace
length not exceed one-quarter inch (6 mm). Refer to
Section 26.3 “On-Chip Voltage Regulator” for
details.
2.4 Master Clear (MCLR) Pin
The MCLR pin provides for two specific device
functions:
• Device Reset
• Device Programming and Debugging
Pulling The MCLR pin low generates a device reset.
Figure 2-2 illustrates a typical MCLR circuit. During
device programming and debugging, the resistance
and capacitance that can be added to the pin must
be considered. Device programmers and debuggers
drive the MCLR pin. Consequently, specific voltage
levels (VIH and VIL) and fast signal transitions must
not be adversely affected. Therefore, specific values
of R and C will need to be adjusted based on the
application and PCB requirements.
For example, as illustrated in Figure 2-2, it is
recommended that the capacitor C, be isolated from
the MCLR pin during programming and debugging
operations.
Place the components shown in Figure 2-2 within
one-quarter inch (6 mm) from the MCLR pin.
FIGURE 2-2:
EXAMPLE OF MCLR PIN
CONNECTIONS
VDD
R
R1
MCLR
JP
PIC32MX
C
Note 1: R ≤ 10 kΩ is recommended. A suggested
starting value is 10 kΩ. Ensure that the MCLR
pin VIH and VIL specifications are met.
2: R1 ≤ 470Ω will limit any current flowing into
MCLR from the external capacitor C, in the
event of MCLR pin breakdown, due to
Electrostatic Discharge (ESD) or Electrical
Overstress (EOS). Ensure that the MCLR pin
VIH and VIL specifications are met.
3: The capacitor can be sized to prevent uninten-
tional resets from brief glitches or to extend the
device reset period during POR.
DS61143G-page 32
© 2010 Microchip Technology Inc.