AS1901, AS1902, AS1903

Ultra Low-Power µP Supervisory Circuit

Dat a Sh eet

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Revision 1.51

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1 General Description

The AS1901/2/3 family is an ultra low-power supervisory

circuit device.

The device can be used to monitor the supply voltage of

digital systems and microprocessors and initiate a reset

when the voltage goes below a predefined threshold.

The duration of the reset is 5/20/100/500ms (typ.) after

the supply voltage has risen above the threshold.

The AS1901/2/3 exhibit excellent reliability and can

reduce application costs by eliminating all external com-

ponents.

The device is available with different output drivers:

!

The AS1901 has a push-pull driver with an active low

reset.

!

The AS1902 uses the same output stage as the

AS1901, but has an active high reset.

!

The AS1903 has an open drain output with active low

reset.

All devices operate down to a voltage of 1V.

The reset thresholds are factory-trimmable between

2.2V and 3.08V in steps of approximately 100mV.

Each device of the AS1901/2/3 family is offered with four

time-out periods of 5/20/100/500ms.

The extremely low current consumption of only 230nA

(typ) at 3.3V makes the device ideal for use in portable

applications.

All devices are available in a 3-pin SOT23 package.

Figure 1. Functional Block Diagrams

2 Key Features

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Low 230nA (typ) Supply Current

!

Precision Monitoring of 2.5-, 3-, and 3.3V-Power

Supplies

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Supply Voltage Range: 1.0 to 3.6V

!

Reset Threshold Range: 2.2 to 3.1V

!

Available in 3 Versions:

- AS1901 Push Pull RESETN

- AS1902 Push Pull RESET

- AS1903 Open Drain RESETN

!

4 Time-Out Periods Ranging from 5 to 500ms

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Detection Voltage Accuracy: ±1.5%

!

Temperature Range: -40 to +85°C

!

Package: SOT23-3

3 Applications

The devices are ideal for computers, intelligent instru-

ments, controllers, critical microprocessor and micro-

controller, power monitoring and portable/battery-

powered equipment.

AS1903

Microprocessor

GND

GND

RESETN

RESET I/O

1

2

3

AS1901

AS1902

Microprocessor

GND

GND

RESETN,

RESET

RESET

1

2

3