DEVICE OVERVIEW
The PIC16F631/677/685/687/689/690 devices are covered by this data sheet. They are available in 20-pin PDIP, SOIC, TSSOP and QFN packages. Block Diagrams and pinout descriptions of the devices are as follows:

• PIC16F631 (Figure 1-1, Table 1-1)
• PIC16F677 (Figure 1-2, Table 1-2)
• PIC16F685 (Figure 1-3, Table 1-3)
• PIC16F687/PIC16F689 (Figure 1-4, Table 1-4)
• PIC16F690 (Figure 1-5, Table 1-5)

High-Performance RISC CPU:
• Only 35 instructions to learn:
- All single-cycle instructions except branches
• Operating speed:
- DC – 20 MHz oscillator/clock input
- DC – 200 ns instruction cycle
• Interrupt capability
• 8-level deep hardware stack
• Direct, Indirect and Relative Addressing modes
Special Microcontroller Features:
• Precision Internal Oscillator:
- Factory calibrated to ± 1%
- Software selectable frequency range of 8 MHz to 32 kHz
- Software tunable
- Two-Speed Start-up mode
- Crystal fail detect for critical applications
- Clock mode switching during operation for power savings
• Power-Saving Sleep mode
• Wide operating voltage range (2.0V-5.5V)
• Industrial and Extended Temperature range
• Power-on Reset (POR)
• Power-up Timer (PWRTE) and Oscillator Start-up Timer (OST)
• Brown-out Reset (BOR) with software control option
• Enhanced low-current Watchdog Timer (WDT) with on-chip oscillator (software selectable nominal 268 seconds with full prescaler) with software enable
• Multiplexed Master Clear/Input pin
• Programmable code protection
• High Endurance Flash/EEPROM cell:
- 100,000 write Flash endurance
- 1,000,000 write EEPROM endurance
- Flash/Data EEPROM retention: > 40 years
• Enhanced USART module:
- Supports RS-485, RS-232 and LIN 2.0
- Auto-Baud Detect
- Auto-wake-up on Start bit