Microchip Technology AC244045 Data Sheet

© 2009 Microchip Technology Inc.

DS41341E-page 51

The PIC16F72X devices differ from the PIC16LF72X
devices due to an internal Low Dropout (LDO) voltage
regulator. The PIC16F72X contain an internal LDO,
while the PIC16LF72X do not.

The lithography of the die allows a maximum operating
voltage of 3.6V on the internal digital logic. In order to
continue to support 5.0V designs, a LDO voltage
regulator is integrated on the die. The LDO voltage
regulator allows for the internal digital logic to operate
at 3.2V, while I/O’s operate at 5.0V (V

DD

).

The LDO voltage regulator requires an external bypass
capacitor for stability. One of three pins, denoted as
V

CAP

, can be configured for the external bypass

capacitor. It is recommended that the capacitor be a
ceramic cap between 0.1 to 1.0 µF. The V

CAP

 pin is not

intended to supply power to external loads. An external
voltage regulator should be used if this functionality is
required. In addition, external devices should not
supply power to the V

CAP

 pin.

On power-up, the external capacitor will look like a
large load on the LDO voltage regulator. To prevent
erroneous operation, the device is held in Reset while
a constant current source charges the external
capacitor. After the cap is fully charged, the device is
released from Reset. For more information, refer to
Section 23.0 “Electrical Specifications”.

See Configuration Word 2 register (Register 8-2) for
V

CAP

 enable bits.