Supervisory Circuits with Windowed

Watchdog and Manual Reset in 5-Lead SOT-23

Data Sheet

ADM8323/ADM8324

Rev. 0

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FEATURES

Windowed watchdog, 8 timeout options

26 reset threshold options

2.5 V to 5 V in 100 mV increments

4 reset timeout options

1 ms, 20 ms, 140 ms, and 1120 ms (minimum)

Manual reset input

Open-drain or push-pull RESET outputs

Low power consumption

Specified over wide temperature range (−40°C to +125°C)

Qualified for automotive applications

5-lead SOT-23 package

APPLICATIONS

Automotive

Microprocessor systems

Computers

Controllers

Intelligent instruments

Portable equipment

FUNCTIONAL BLOCK DIAGRAMS

Figure 1.

Figure 2.

GENERAL DESCRIPTION

The ADM8323/ADM8324 are supervisory circuits that monitor

power supply voltage levels and code execution integrity in

microprocessor-based systems. An on-chip watchdog timer

checks for activity within a preset timeout window. A reset

signal can also be asserted by an external push-button switch

through a manual reset input. The RESET output is either push-

pull (ADM8323) or open-drain (ADM8324).

A watchdog failure results in a low output on the RESET pin.

A failure can be triggered either by a fast watchdog error

(watchdog pulses too close together) or by a slow watchdog

error (no watchdog pulse within the timeout period). This

effectively gives a window in which to observe the watchdog

pulse. The watchdog timeout is measured from the last falling

edge of the watchdog input (WDI). There are eight different

watchdog windows available, as shown in Table 5.

Each device is available in a choice of 26 reset threshold options

from 2.5 V to 5 V in 100 mV increments. There are also four

reset timeout options of 1 ms, 20 ms, 140 ms, and 1120 ms

(minimum).

The ADM8323/ADM8324 are available in a 5-lead SOT-23

package and typically consume only 10 μA, making them

suitable for use in low power portable applications.

ADM8323

MR

GND

WDI

RESET

RESET

GENERATOR

WINDOWED

WATCHDOG

DETECTOR

DEBOUNCE

ADM8324

MR

GND

WDI

RESET

RESET

GENERATOR

WINDOWED

WATCHDOG

DETECTOR

DEBOUNCE