MAX6723AUTTFD3 View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX6723AUTTFD3

Dual/Triple, Ultra-Low-Voltage, SOT23 µP Supervisory Circuits

Maxim Integrated 

Dual/Triple, Ultra-Low-Voltage, SOT23 µP

Supervisory Circuits

magnitude indicated (reset threshold overdrive). The

graph shows the maximum pulse width that a negative-

going VCC transient may typically have without causing

a reset pulse to be issued. As the amplitude of the tran-

sient increases (i.e., goes farther below the reset

threshold), the maximum allowable pulse width

decreases. A 0.1µF bypass capacitor mounted close to

the VCC pin provides additional transient immunity.

Watchdog Software Considerations

Setting and resetting the watchdog input at different

points in the program, rather than “pulsing” the watch-

dog input high-low-high or low-high-low, helps the

watchdog timer to closely monitor software execution.

This technique avoids a “stuck” loop where the watch-

dog timer continues to be reset within the loop, keeping

the watchdog from timing out. Figure 6 shows an exam-

ple flow diagram where the I/O driving the watchdog

input is set high at the beginning of the program, set low

at the beginning of every subroutine or loop, then set

high again when the program returns to the beginning. If

the program should “hang” in any subroutine, the I/O is

continually set low and the watchdog timer is allowed to

time out, causing a reset or interrupt to be issued.

START

SET WDI

HIGH

PROGRAM

CODE

SUBROUTINE OR

PROGRAM LOOP

SET WDI LOW

SUBROUTINE

COMPLETED

HANG IN

SUBROUTINE

RETURN

Figure 6. Watchdog Flow Diagram

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