AS1920, AS1922

Triple-Voltage, Micro-Power Microprocessor

Supervisory Circuits

Pro duct Brief

www.austriamicrosystems.com

Revision 0.65

1 - 2

1 General Description

The AS1920 and AS1922 microprocessor supervisory

circuits were designed to generate a reset when at least

one of the three monitored supply voltages falls below

its respective trip threshold.

These very-low-current (6.5µA, typ) devices maintain

reset for a minimum timeout period after all supplies

have stabilized. Guaranteed to be in the correct state for

age systems with low current requirements and strict

monitoring requirements.

The devices are available as the standard products

All devices monitor primary and secondary factory-

trimmed voltages. Additionally, a third monitoring voltage

can be selected via an external resistor divider.

The AS1920 has an active-low push/pull reset output,

whereas the AS1922 has an active-low open-drain reset

output.

The AS1920 and AS1922 are available in a 5-pin

SOT23 package.

Figure 1. Typical Application Diagram

2 Key Features

!

Simultaneous Triple-Voltage Monitoring

!

Very-Low Supply Current: 6.5µA

!

±1.5% Accuracy Over Temperature

!

Reset Time Delay: 200ms

!

Power Supply Transient Immunity

!

!

Active-Low Push/Pull Reset Output (AS1920)

!

Active-Low Open-Drain Reset Output (AS1922)

!

5-pin SOT23 Package

3 Applications

The devices are ideal for personal computers, note-

books, battery-powered systems, embedded controllers,

intelligent instruments, automotive systems, critical CPU

monitoring, and any multi-supply monitoring application.

Table 1. Standard Products

Model

Output Type

Supervisory Voltages

AS1920-18

Push/Pull

3V, 1.8V, Adjustable

AS1922-18

Open-Drain

3V, 1.8V, Adjustable

3V

System

Logic

1.8V

2.5V

AS1920/

AS1922

0.1µF

130k

Ω

1%

100k

Ω

1%

0.1µF

1

RESETN

3

2

GND

4

5