AS1904, AS1905, AS1906

Ultra Low-Power µP Supervisory Circuit

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1 General Description

The AS1904/5/6 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 device exhibits excellent reliability and can reduce

application costs by eliminating all external components.

The device is available with different output drivers:

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The AS1904 has a push-pull driver with an active low

reset.

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The AS1905 uses the same output stage as the

AS1904, but has an active high reset.

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The AS1906 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 AS1904/5/6 family is offered with four

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

The extremely low current consumption of only 150nA

(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 150nA (typical) Supply Current

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

Supplies

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Supply Voltage Range 1.0 to 3.6V

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Reset Threshold Available from 2.2 to 3.1V

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Available in three Versions

- AS1904 Push-Pull RESETN

- AS1905 Push-Pull RESET

- AS1906 Open Drain RESETN

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4 Time-Out Periods Ranging from 5 to 500ms

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Detection Voltage Accuracy: ±1.5%

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Temperature Range: -40 to +85°C

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SOT23-3 Package

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Superior Upgrade to austriamicrosystems

AS1901/2/3 Device Family

3 Applications

The devices are ideal for computers, intelligent instru-

ments, controllers, critical microprocessor and micro-

controller, power monitoring and portable/battery-

powered equipment.

AS1906

Microprocessor

GND

GND

RESETN

RESET I/O

1

2

3

AS1904

AS1905

Microprocessor

GND

GND

RESET,

RESETN

RESET

1

2

3

World's

Lowest

Power

Consu

mption

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