Datasheet

PIC24HJ12GP201/202
DS70282E-page 16 © 2007-2011 Microchip Technology Inc.
FIGURE 2-1: RECOMMENDED
MINIMUM CONNECTION
2.2.1 TANK CAPACITORS
On boards with power traces running longer than six
inches in length, it is suggested to use a tank capacitor
for integrated circuits including microcontrollers to sup-
ply a local power source. The value of the tank capaci-
tor should be determined based on the trace resistance
that connects the power supply source to the microcon-
troller, and the maximum current drawn by the micro-
controller in the application. In other words, select the
tank capacitor so that it meets the acceptable voltage
sag at the device. Typical values range from 4.7 µF to
47 µF.
2.3 CPU Logic Filter Capacitor
Connection (V
CAP)
A low-ESR (<5 Ohms) capacitor is required on the
V
CAP pin, which is used to stabilize the voltage
regulator output voltage. The V
CAP pin must not be
connected to V
DD, and must have a capacitor between
4.7 µF and 10 µF, 16V connected to ground. The type
can be ceramic or tantalum. Refer to Section 22.0
“Electrical Characteristics” for additional
information.
The placement of this capacitor should be close to the
V
CAP. It is recommended that the trace length not
exceed one-quarter inch (6 mm). Refer to Section 19.2
“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
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 shown in Figure 2-2, it is
recommended that capacitor C is 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
PIC24H
VDD
VSS
VDD
VSS
VSS
VDD
AVDD
AVSS
VDD
VSS
0.1 µF
Ceramic
0.1 µF
Ceramic
0.1 µF
Ceramic
0.1 µF
Ceramic
C
R
V
DD
MCLR
0.1 µF
Ceramic
VCAP
10 Ω
R1
10 µF
Tantalum
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 Elec-
trostatic Discharge (ESD) or Electrical
Overstress (EOS). Ensure that the MCLR
pin
V
IH and VIL specifications are met.
C
R1
R
V
DD
MCLR
PIC24H
JP