Microchip Technology MA330019 Data Sheet
© 2007-2012 Microchip Technology Inc.
DS70291G-page 19
dsPIC33FJ32MC302/304, dsPIC33FJ64MCX02/X04 AND dsPIC33FJ128MCX02/X04
2.5
ICSP Pins
The PGECx and PGEDx pins are used for In-Circuit
Serial Programming™ (ICSP™) and debugging
purposes. 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 a 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
communications 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 (V
Serial Programming™ (ICSP™) and debugging
purposes. 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 a 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
communications 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 (V
IH
)
and input low (V
IL
) 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
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
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 Emulator User’s
Guide” (DS51616)
• “Using MPLAB
®
REAL ICE™” (poster) (DS51749)
2.6
External Oscillator Pins
Many DSCs have options for at least two oscillators: a
high-frequency primary oscillator and a low-frequency
secondary oscillator (refer to
high-frequency primary oscillator and a low-frequency
secondary oscillator (refer to
for details).
The oscillator circuit should be placed on the same
side of the board as the device. Also, place the
oscillator circuit close to the respective oscillator pins,
not exceeding one-half inch (12
side of the board as the device. Also, place the
oscillator circuit close to the respective oscillator pins,
not exceeding one-half inch (12
mm) distance
between them. The load capacitors should be placed
next to the oscillator itself, on the same side of the
board. Use a grounded copper pour around the
oscillator circuit to isolate them from surrounding
circuits. The grounded copper pour should be routed
directly to the MCU ground. Do not run any signal
traces or power traces inside the ground pour. Also, if
using a two-sided board, avoid any traces on the
other side of the board where the crystal is placed. A
suggested layout is shown in
next to the oscillator itself, on the same side of the
board. Use a grounded copper pour around the
oscillator circuit to isolate them from surrounding
circuits. The grounded copper pour should be routed
directly to the MCU ground. Do not run any signal
traces or power traces inside the ground pour. Also, if
using a two-sided board, avoid any traces on the
other side of the board where the crystal is placed. A
suggested layout is shown in
Recommendations for crystals and ceramic
resonators are provided in
resonators are provided in
respectively.
FIGURE 2-3:
SUGGESTED PLACEMENT
OF THE OSCILLATOR
CIRCUIT
OF THE OSCILLATOR
CIRCUIT
TABLE 2-1:
CRYSTAL RECOMMENDATIONS
13
Main Oscillator
Guard Ring
Guard Trace
Secondary
Oscillator
Oscillator
14
15
16
17
18
19
20
Part
Number
Vendor
Freq.
Load
Cap.
Package
Case
Frequency
Tolerance
Mounting
Type
Operating
Temperature
ECS-40-20-4DN
ECS Inc.
4 MHz
20 pF
HC49/US
±30 ppm
TH
-40°C to +85°C
ECS-80-18-4DN
ECS Inc.
8 MHz
18 pF
HC49/US
±30 ppm
TH
-40°C to +85°C
ECS-100-18-4-DN
ECS Inc.
10 MHz
18 pF
HC49/US
±30 ppm
TH
-40°C to +85°C
ECS-200-20-4DN
ECS Inc.
20 MHz
20 pF
HC49/US
±30 ppm
TH
-40°C to +85°C
ECS-40-20-5G3XDS-TR
ECS Inc.
4 MHz
20 pF
HC49/US
±30 ppm
SM
-40°C to +125°C
ECS-80-20-5G3XDS-TR
ECS Inc.
8 MHz
20 pF
HC49/US
±30 ppm
SM
-40°C to +125°C
ECS-100-20-5G3XDS-TR ECS Inc.
10 MHz
20 pF
HC49/US
±30 ppm
SM
-40°C to +125°C
ECS-200-20-5G3XDS-TR ECS Inc.
20 MHz
20 pF
HC49/US
±30 ppm
SM
-40°C to 125°C
NX3225SA 20MHZ AT-W NDK
20 MHz
8 pF
3.2 mm x 2.5 mm
±50 ppm
SM
-40°C to 125°C
Legend:
TH = Through Hole
SM = Surface Mount