PIC12F639 Microchip Technology, PIC12F639 Datasheet - Page 113

• Manufacturer Part Number: PIC12F639
• Description: (PIC12F635 / PIC12F636 / PIC12F639) 8/14-PIN FLASH-BASED / 8-BIT CMOS MICROCONTROLLERS WITH NANOWATT TECHNOLOGY
• Manufacturer: Microchip Technology

12.0
The PIC12F635/PIC16F636/639 has a host of features
intended to maximize system reliability, minimize cost
through elimination of external components, provide
power saving features and offer code protection.
These features are:
• Reset
• Interrupts
• Watchdog Timer (WDT)
• Oscillator selection
• Sleep
• Code protection
• ID Locations
• In-Circuit Serial Programming
© 2005 Microchip Technology Inc.
- Power-on Reset (POR)
- Wake-up Reset (WUR)
- Power-up Timer (PWRT)
- Oscillator Start-up Timer (OST)
- Brown-out Detect (BOD)
SPECIAL FEATURES OF THE
CPU
PIC12F635/PIC16F636/639
Preliminary
The PIC12F635/PIC16F636/639 has two timers that
offer necessary delays on power-up. One is the
Oscillator Start-up Timer (OST), intended to keep the
chip in Reset until the crystal oscillator is stable. The
other is the Power-up Timer (PWRT), which provides a
fixed delay of 64 ms (nominal) on power-up only,
designed to keep the part in Reset while the power
supply stabilizes. There is also circuitry to reset the
device if a brown-out occurs, which can use the Power-
up Timer to provide at least a nominal 64 ms Reset.
With these three functions on-chip, most applications
need no external Reset circuitry.
The Sleep mode is designed to offer a very low-current
Power-down mode. The user can wake-up from Sleep
through:
• External Reset
• Watchdog Timer Wake-up
• An Interrupt
Several oscillator options are also made available to
allow the part to fit the application. The INTOSC option
saves system cost while the LP crystal option saves
power. A set of configuration bits are used to select
various options (see Register 12-1).
DS41232B-page 111