Microchip Technology MCP3421DM-WS Data Sheet

© 2009 Microchip Technology Inc.

 

DS39632E-page 291

PIC18F2455/2550/4455/4550 devices include several
features intended to maximize reliability and minimize
cost through elimination of external components.
These are:
• Oscillator Selection
• Resets:

- Power-on Reset (POR)
- Power-up Timer (PWRT)
- Oscillator Start-up Timer (OST)
- Brown-out Reset (BOR)

• Interrupts
• Watchdog Timer (WDT)
• Fail-Safe Clock Monitor
• Two-Speed Start-up
• Code Protection
• ID Locations
• In-Circuit Serial Programming
The oscillator can be configured for the application
depending on frequency, power, accuracy and cost. All
of the options are discussed in detail in Section 2.0
“Oscillator Configurations”.
A complete discussion of device Resets and interrupts
is available in previous sections of this data sheet.

In addition to their Power-up and Oscillator Start-up Tim-
ers provided for Resets, PIC18F2455/2550/4455/4550
devices have a Watchdog Timer, which is either
permanently enabled via the Configuration bits or
software controlled (if configured as disabled).
The inclusion of an internal RC oscillator also provides
the additional benefits of a Fail-Safe Clock Monitor
(FSCM) and Two-Speed Start-up. FSCM provides for
background monitoring of the peripheral clock and
automatic switchover in the event of its failure.
Two-Speed Start-up enables code to be executed
almost immediately on start-up, while the primary clock
source completes its start-up delays. 
All of these features are enabled and configured by
setting the appropriate Configuration register bits.