timeout period, then momentarily pulses high, resetting

the watchdog counter. When WDI is left unconnected,

the watchdog timer is cleared by this internal driver just

before the timeout period is reached (the internal driver

three-stated, the maximum allowable leakage current of

the device driving WDI is 10µA.

In normal mode (WDS = GND), the watchdog timer

cannot be disabled by three-stating WDI. WDI is a

high-impedance input in this mode. Do not leave WDI

unconnected in normal mode.

+5V, Low-Power µP Supervisory Circuits

with Adjustable Reset/Watchdog

_______________________________________________________________________________________

7

0V

0V

WDI

RESET

NORMAL MODE (WDS = GND)

0V

0V

WDI

RESET

Figure 2a. Watchdog Timing Diagram, WDS = GND

0.1µF

MAX6301

MAX6302

MAX6303

MAX6304

GND

2.67

2.67

SRT

SWT