uP constitute a watchdog circuit monitors

MAX706's internal watchdog timer timing of 1.6 seconds, if within 1.6 seconds, the watchdog input pin WDI maintained at a predetermined level (high or low), the watchdog output Duanli goes low, diode D is turned on, so that a low level is applied to the reset terminal, MAX706 generates a reset signal RESET reset the device until it is cleared after reset watchdog, Li only goes high. When WDI has an edge (rising or falling) signal, the watchdog timer is cleared.