austriamicrosystems
AS1901, AS1902, AS1903
Ultra Low-Power µP Supervisory Circuit
Data Sheet
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
VCC
3
VDD
VCC
2 Key Features
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
4 Time-Out Periods Ranging from 5 to 500ms
Detection Voltage Accuracy: ±1.5%
Temperature Range: -40 to +85°C
Package: SOT23-3
Pin Compatible to MAX6326/6327/6328
3 Applications
Computers
Intelligent Instruments
Controllers
Critical Microprocessor and Microcontroller
Power Monitoring
Portable/Battery-Powered Equipment
Automotive
VCC
3
VDD
VCC
AS1901
AS1902
RESETN, 2
RESET
GND
1
Microprocessor
RESET
GND
AS1903
2
RESETN
GND
1
Microprocessor
RESET I/O
GND
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Revision 1.5
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