Datasheet
PIC32MX5XX/6XX/7XX
DS61156D-page 164 © 2010 Microchip Technology Inc.
28.3 On-Chip Voltage Regulator
All PIC32MX5XX/6XX/7XX devices’ core and digital
logic are designed to operate at a nominal 1.8V. To
simplify system designs, most devices in the
PIC32MX5XX/6XX/7XX family incorporate an on-chip
regulator providing the required core logic voltage from
V
DD.
A low-ESR capacitor (such as tantalum) must be con-
nected to the V
CAP/VDDCORE pin (see Figure 28-2).
This helps to maintain the stability of the regulator.
The recommended value for the filter capacitor is
provided in
Section 31.1 “DC Characteristics”.
28.3.1 ON-CHIP REGULATOR AND POR
It takes a fixed delay for the on-chip regulator to generate
an output. During this time, designated as T
PU, code exe-
cution is disabled. T
PU is applied every time the device
resumes operation after any power-down, including
Sleep mode.
If the regulator is disabled, a separate Power-up Timer
(PWRT) is automatically enabled. The PWRT adds a
fixed delay of T
PWRT at device start-up. See
Section 31.0 “Electrical Characteristics” for more
information on T
PU AND TPWRT.
28.3.2 ON-CHIP REGULATOR AND BOR
PIC32MX5XX/6XX/7XX devices also have a simple
brown-out capability. If the voltage supplied to the reg-
ulator is inadequate to maintain a regulated level, the
regulator Reset circuitry will generate a Brown-out
Reset. This event is captured by the BOR flag bit
(RCON<1>). The brown-out voltage levels are specific
in
Section 31.1 “DC Characteristics”.
28.3.3 POWER-UP REQUIREMENTS
The on-chip regulator is designed to meet the power-up
requirements for the device. If the application does not
use the regulator, then strict power-up conditions must
be adhered to. While powering up, V
DDCORE must
never exceed V
DD by 0.3 volts.
FIGURE 28-2: CONNECTIONS FOR THE
ON-CHIP REGULATOR
Note: It is important that the low-ESR capacitor
is placed as close as possible to the
V
CAP/VDDCORE pin.
VDD
VCAP/VDDCORE
VSS
PIC32MX
CEFC
(2)
3.3V
(1)
Note 1: These are typical operating voltages. Refer
to
Section 31.1 “DC Characteristics”
for
the full operating ranges of V
DD and
V
DDCORE.
2: It is important that the low-ESR capacitor
is placed as close as possible to the
V
CAP/VDDCORE pin.
(10 μF typ)