This application note compares the benefits and drawbacks of internal (integrated with the microprocessor) and external (hardware-based) watchdog timers (WDTs). It explains that internal watchdog timers are easy to implement, but subject to failure. The MAXQ2000 microcontroller’s WDT serves as an example of an internal watchdog. Hardware-based watchdog timers require additional board space, but are indispensable when reliability is paramount. This app note concludes with a comparison matrix that highlights the main advantages and disadvantages of each WDT solution.