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PIC32MX1XX_12 Datasheet, PDF (28/328 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
2.3 Capacitor on Internal Voltage
Regulator (VCAP)
2.3.1 INTERNAL REGULATOR MODE
A low-ESR (1 ohm) capacitor is required on the VCAP
pin, which is used to stabilize the internal voltage regu-
lator output. The VCAP 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.
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 illustrated in Figure 2-2 within
one-quarter inch (6 mm) from the MCLR pin.
FIGURE 2-2:
VDD
MCLR PIN CONNECTIONS
R(1)
JP
C(3)
R1(2)
MCLR
PIC32
Note 1:
2:
3:
R  10 k is recommended. A suggested
starting value is 10 k. Ensure that the MCLR
pin VIH and VIL specifications are met.
R1  470 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.
The capacitor can be sized to prevent uninten-
tional Resets from brief glitches or to extend
the device Reset period during POR.
2.5 ICSP Pins
The PGECx and PGEDx pins are used for In-Circuit
Serial Programming™ (ICSP™) and debugging pur-
poses. It is recommended to keep the trace length
between the ICSP connector and the ICSP pins on the
device as short as possible. If the ICSP connector is
expected to experience an ESD event, a series resistor
is recommended, with the value in the range of a few
tens of Ohms, not to exceed 100 Ohms.
Pull-up resistors, series diodes and capacitors on the
PGECx and PGEDx pins are not recommended as they
will interfere with the programmer/debugger communi-
cations to the device. If such discrete components are
an application requirement, they should be removed
from the circuit during programming and debugging.
Alternatively, refer to the AC/DC characteristics and
timing requirements information in the respective
device Flash programming specification for information
on capacitive loading limits and pin input voltage high
(VIH) and input low (VIL) requirements.
Ensure that the “Communication Channel Select” (i.e.,
PGECx/PGEDx pins) programmed into the device
matches the physical connections for the ICSP to
MPLAB® ICD 3 or MPLAB REAL ICE™.
For more information on ICD 3 and REAL ICE
connection requirements, refer to the following
documents that are available on the Microchip web
site.
• “Using MPLAB® ICD 3” (poster) DS51765
• “MPLAB® ICD 3 Design Advisory” DS51764
• “MPLAB® REAL ICE™ In-Circuit Debugger
User’s Guide” DS51616
• “Using MPLAB® REAL ICE™ Emulator” (poster)
DS51749
2.6 JTAG
The TMS, TDO, TDI and TCK pins are used for testing
and debugging according to the Joint Test Action
Group (JTAG) standard. It is recommended to keep the
trace length between the JTAG connector and the
JTAG pins on the device as short as possible. If the
JTAG connector is expected to experience an ESD
event, a series resistor is recommended, with the value
in the range of a few tens of Ohms, not to exceed 100
Ohms.
Pull-up resistors, series diodes and capacitors on the
TMS, TDO, TDI and TCK pins are not recommended
as they will interfere with the programmer/debugger
communications to the device. If such discrete compo-
nents are an application requirement, they should be
removed from the circuit during programming and
debugging. Alternatively, refer to the AC/DC character-
istics and timing requirements information in the
respective device Flash programming specification for
information on capacitive loading limits and pin input
voltage high (VIH) and input low (VIL) requirements.
DS61168E-page 28
Preliminary
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