PIC18F-LF1XK50 Datasheet, PDF (81/420 Pages) Microchip Technology – 20-Pin USB Flash Microcontrollers

PIC18F1XK50/PIC18LF1XK50
8.0 LOW DROPOUT (LDO)
VOLTAGE REGULATOR
The PIC18F1XK50 devices differ from the
PIC18LF1XK50 devices due to an internal Low
Dropout (LDO) voltage regulator. The PIC18F1XK50
contain an internal LDO, while the PIC18LF1XK50 do
not.
The lithography of the die allows a maximum operating
voltage of the nominal 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 3.3V, while I/O’s operate at 5.0V (VDD).
The LDO voltage regulator requires an external bypass
capacitor for stability. The VUSB pin is required to have
an external bypass capacitor. It is recommended that
the capacitor be a ceramic cap between 0.22 to 0.47 µF.
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 27.0 “Electrical Specifications”.
 2010 Microchip Technology Inc.
Preliminary
DS41350E-page 81