AS1923

Quad-Voltage Microprocessor Supervisory Circuit

www.austriamicrosystems.com/Supervisors/AS1923

Revision 1.01

1 - 16

Data sheet

1 General Description

The AS1923 microprocessor supervisory circuit was designed to

monitor up to four system supply voltages without the need for exter-

nal components, and asserts a single reset if any of the monitored

supply voltages drops below its reset threshold.

The AS1923 features an active-low reset output that is asserted

when any of the 4 monitored voltages are below their respective

reset threshold. The reset output is open-drain with a weak internal

pullup (10µA) to IN2. Reset remains low for a specified reset timeout

period (120ms min) after all voltages have stabilized. The output is

valid as long as the IN1 or IN2 input voltage remains >1V.

Minimal external component requirements, small size, and wide tem-

perature range (-40 to +85°C) greatly improves reliability compared

to individual supervisory circuits or discrete components.

A wide range of factory-trimmed threshold voltages are available to

accommodate many different supply voltages/tolerances with mini-

mal external component requirements.

Factory-trimmed options are available for monitoring +5.0, +3.3,

+3.0, +2.5, +1.8, and -5.0V supplies with -5% and/or -10% toler-

ances. The device is also available with one or two user-adjustable

threshold options (via external resistor-divider network) if non-stan-

dard voltage thresholds are required.

The AS1923 is available in an 6-pin SOT23 package.

Figure 1. AS1923 - Typical Application

2 Key Features

Simultaneous Quad-Voltage Monitoring

Precision Factory-Trimmed Reset Threshold Options: +5.0,

+3.3, +3.0, +2.5, +1.8, and -5.0V

User-Adjustable Voltage Monitoring Threshold Options

Low Supply Current: 55µA

Open-Drain – AS1923A

10µA Current Source Pullup – AS1923B

Reset Timeout Period: 120ms

RESET Valid to IN1 = 1V or IN2 = 1V

Immune to Fast INx Transients

External Components not Required

Guaranteed Performance: Operating Temperature Range = -40

to +85ºC

6-pin SOT23 Package

3 Applications

The device is ideal for portable and battery-powered systems,

embedded controllers, intelligent instruments, automotive systems,

critical CPU monitoring, and any multi-supply application.

4

IN1

GND

2

AS1923

CPU

Monitoring

Voltage 1

Monitoring

Voltage 2

Monitoring

Voltage 3

Monitoring

Voltage 4

6

IN3

1

IN4

5

IN2

3

RESETN

RESETN