DV164136 Microchip Technology, DV164136 Datasheet - Page 325

• Manufacturer Part Number: DV164136
• Description: DEVELOPMENT KIT FOR PIC18
• Manufacturer: Microchip Technology
• Series: PIC®r
• Type: MCUr

Specifications of DV164136

• Contents: Board, Cables, CDs, PICkit™ 3 Programmer, Power Supply
• Processor To Be Evaluated: PIC18F8722, PIC18F87J11
• Interface Type: RS-232, USB
• Operating Supply Voltage: 3.3 V, 5 V
• Silicon Manufacturer: Microchip
• Core Architecture: PIC
• Core Sub-architecture: PIC18
• Silicon Core Number: PIC18F
• Silicon Family Name: PIC18F8xxx
• Kit Contents: PIC18 Exp Brd PICkit 3 Cable CD PSU
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: PIC18F8722, PIC18F87J11
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

24.3
All of the PIC18F87J11 family devices power their core
digital logic at a nominal 2.5V. For designs that are
required to operate at a higher typical voltage, such as
3.3V, all devices in the PIC18F87J11 family incorporate
an on-chip regulator that allows the device to run its
core logic from V
The regulator is controlled by the ENVREG pin. Tying
V
provides power to the core from the other V
When the regulator is enabled, a low-ESR filter capac-
itor must be connected to the V
(Figure 24-2). This helps to maintain the stability of the
regulator. The recommended value for the filter capac-
itor is provided in Section 27.3 “DC Characteristics:
PIC18F87J11 Family (Industrial)”.
If ENVREG is tied to V
this case, separate power for the core logic at a nomi-
nal 2.5V must be supplied to the device on the
V
levels, typically 3.3V. Alternatively, the V
and V
nominal voltage. Refer to Figure 24-2 for possible
configurations.
24.3.1
When it is enabled, the on-chip regulator provides a
constant voltage of 2.5V nominal to the digital core
logic. The regulator can provide this level from a V
about 2.5V, all the way up to the device’s V
does not have the capability to boost V
2.5V. In order to prevent “brown-out” conditions, when
the voltage drops too low for the regulator, the regulator
enters Tracking mode. In Tracking mode, the regulator
output follows V
100 mV.
The on-chip regulator includes a simple, Low-Voltage
Detect (LVD) circuit. If V
approximately 2.45V on V
Low-Voltage Detect Interrupt Flag, LVDIF (PIR2<2>).
This can be used to generate an interrupt and put the
application into a low-power operational mode, or
trigger an orderly shutdown. Low-Voltage Detection is
only available when the regulator is enabled.
The Low-Voltage Detect interrupt is edge-sensitive.
The interrupt flag will only be set once per falling edge
of V
a new interrupt will not be generated until V
rises back above, and then falls below, the 2.45 thresh-
old. Upon device Resets, the interrupt flag will reset to
‘0’, even if V
regulator is enabled, the LVDSTAT bit in the WDTCON
register can be polled to determine the current level of
V
© 2009 Microchip Technology Inc.
DD
DDCORE
DDCORE
DDCORE
to the pin enables the regulator, which in turn,
DD
pins can be tied together to operate at a lower
On-Chip Voltage Regulator
/V
.
CAP
VOLTAGE REGULATOR TRACKING
MODE AND LOW-VOLTAGE
DETECTION
. Firmware can clear the interrupt flag, but
DDCORE
pin to run the I/O pins at higher voltage
DD
DD
.
, with a typical voltage drop of
is less than 2.45V. When the
SS
DD
, the regulator is disabled. In
DDCORE
drops too low to maintain
, the circuit sets the
DDCORE
DD
DDCORE
levels below
/V
DDMAX
DD
CAP
DDCORE
/V
DD
pins.
CAP
pin
. It
of
PIC18F87J11 FAMILY
FIGURE 24-2:
Regulator Enabled (ENVREG tied to V
Regulator Disabled (ENVREG tied to ground):
Regulator Disabled (V
Note 1:
2.5V
2.5V
C
(1)
(1)
F
These are typical operating voltages. Refer
to Section 27.1 “DC Characteristics:
Supply Voltage” for the full operating
ranges of V
3.3V
3.3V
(1)
CONNECTIONS FOR THE
ON-CHIP REGULATOR
V
ENVREG
V
V
DD
DD
DD
DDCORE
SS
PIC18F87J11
tied to V
V
ENVREG
V
V
and V
V
ENVREG
V
V
DD
DDCORE
SS
DD
DDCORE
SS
PIC18F87J11
PIC18F87J11
/V
DDCORE
CAP
DDCORE
/V
/V
DS39778D-page 325
CAP
CAP
.
DD
):
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