48GA004 datasheet(21/268 Pages) MICROCHIP

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 2010 Microchip Technology Inc.

DS39881D-page 21

PIC24FJ64GA004 FAMILY

2.4

Voltage Regulator Pins

(ENVREG/DISVREG and

VCAP/VDDCORE)

The on-chip voltage regulator enable/disable pin

(ENVREG or DISVREG, depending on the device

family) must always be connected directly to either a

supply voltage or to ground. The particular connection

is determined by whether or not the regulator is to be

used:

• For ENVREG, tie to VDD to enable the regulator,

or to ground to disable the regulator

• For DISVREG, tie to ground to enable the

regulator or to VDD to disable the regulator

Refer to Section 24.2 “On-Chip Voltage Regulator”

for details on connecting and using the on-chip

regulator.

When the regulator is enabled, a low-ESR (<5Ω)

capacitor is required on the VCAP/VDDCORE pin to

stabilize the voltage regulator output voltage. The

VCAP/VDDCORE pin must not be connected to VDD, and

must use a capacitor of 10

F connected to ground. The

type can be ceramic or tantalum. A suitable example is

the Murata GRM21BF50J106ZE01 (10

F, 6.3V) or

equivalent. Designers may use Figure 2-3 to evaluate

ESR equivalence of candidate devices.

The placement of this capacitor should be close to

VCAP/VDDCORE. It is recommended that the trace

length not exceed 0.25 inch (6 mm). Refer to

Section 27.0

“Electrical

Characteristics”

for

additional information.

When the regulator is disabled, the VCAP/VDDCORE pin

must be tied to a voltage supply at the VDDCORE level.

Refer to Section 27.0 “Electrical Characteristics” for

information on VDD and VDDCORE.

FIGURE 2-3:

FREQUENCY vs. ESR

PERFORMANCE FOR

SUGGESTED VCAP

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 recom-

mended, with the value in the range of a few tens of

ohms, not to exceed 100Ω.

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.

For device emulation, ensure that the “Communication

Channel Select” (i.e., PGECx/PGEDx pins) programmed

into the device matches the physical connections for the

ICSP to the Microchip debugger/emulator tool.

For

information

available

Microchip

development tools connection requirements, refer to

Section 25.0 “Development Support”

Note:

This section applies only to PIC24FJ

devices with an on-chip voltage regulator.

0.1

0.01

0.001

0.01

0.1

100

1000 10,000

Frequency (MHz)

Note:

Data for Murata GRM21BF50J106ZE01 shown.

Measurements at 25°C, 0V DC bias.

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