AS1901, AS1902, AS1903
Ultra Low-Power µP Supervisory Circuit
D a ta S he e t
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:
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2 Key Features
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Low 230nA (typ) Supply Current
Precision Monitoring of 2.5-, 3-, and 3.3V-Power
Supplies
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
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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.
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4 Time-Out Periods Ranging from 5 to 500ms
Detection Voltage Accuracy: ±1.5%
Temperature Range: -40 to +85°C
Package: SOT23-3
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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.
3 Applications
The devices are ideal for computers, intelligent instru-
ments, controllers, critical microprocessor and micro-
controller, power monitoring and portable/battery-
powered equipment.
Figure 1. Functional Block Diagrams
V
CC
3
V
DD
V
CC
V
CC
3
V
DD
V
CC
AS1901
AS1902
RESETN,
RESET
GND
1
2
Microprocessor
AS1903
2
Microprocessor
RESET
RESETN
RESET I/O
GND
GND
1
GND
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Revision 1.51
1-9
AMSCO [ AUSTRIAMICROSYSTEMS AG ]
