Low Voltage Supervisory Circuits with

Watchdog and Manual Reset in 5-Lead SOT-23

ADM6821/ADM6822/ADM6823/ADM6824/ADM6825

Rev. 0

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FEATURES

Precision low voltage monitoring

9 reset threshold options: 1.58 V to 4.63 V

140 ms (min) reset timeout

Watchdog timer with 1.6 sec timeout

Manual reset input

Reset output stages

Push-pull active-low

Open-drain active-low

Push-pull active-high

Low power consumption (7 μA)

Power supply glitch immunity

Specified from −40°C to +125°C

5-lead SOT-23 package

APPLICATIONS

Microprocessor systems

Computers

Controllers

Intelligent instruments

Portable equipment

FUNCTIONAL BLOCK DIAGRAM

ADM6823

MR

GND

WDI

RESET

RESET

GENERATOR

WATCHDOG

DETECTOR

DEBOUNCE

Figure 1.

GENERAL DESCRIPTION

The ADM682x are supervisory circuits that monitor power

supply voltage levels and code execution integrity in

microprocessor-based systems. As well as providing power-on

reset signals, an on-chip watchdog timer can reset the

microprocessor if it fails to strobe within a preset timeout

period. A reset signal can also be asserted by means of an

external push-button through a manual reset input. The parts

feature different combinations of watchdog input and manual

reset input and output stage configurations, as shown in Table 1.

Each part is available in nine reset threshold options, ranging

from 1.58 V to 4.63 V. The reset and watchdog timeout periods

are fixed at 140 ms (min) and 1.6 sec (typ), respectively.

The ADM682x are available in 5-lead SOT-23 packages and

typically consume only 7 μA, making them suitable for use in

low power, portable applications.

Table 1. Selection Table

Output Stage

Part No.

Watchdog Timer

Manual Reset

RESET

RESET

ADM6821

Yes

Yes

-

Push-Pull

ADM6822

Yes

Yes

Open-Drain

-

ADM6823

Yes

Yes

Push-Pull

-

ADM6824

Yes

-

Push-Pull

Push-Pull

ADM6825

-

Yes

Push-Pull

Push-Pull