austriamicrosystems
Data Sheet
AS1901, AS1902, AS1903
Ultra Low-Power µP Supervisory Circuit
1 General Description
The AS1901/2/3 family is an ultra low-power supervisory
circuit device.
2 Key Features
Low 230nA (typ) Supply Current
Precision Monitoring of 2.5-, 3-, and 3.3V-Power
Supplies
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.
Supply Voltage Range: 1.0 to 3.6V
Reset Threshold Range: 2.2 to 3.1V
Available in 3 Versions:
The AS1901/2/3 exhibit excellent reliability and can
reduce application costs by eliminating all external com-
ponents.
- AS1901 Push Pull RESETN
- AS1902 Push Pull RESET
- AS1903 Open Drain RESETN
The device is available with different output drivers:
The AS1901 has a push-pull driver with an active low
reset.
4 Time-Out Periods Ranging from 5 to 500ms
Detection Voltage Accuracy: 1.5%
Temperature Range: -40 to +85°C
Package: SOT23-3
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.
Pin Compatible to MAX6326/6327/6328
The reset thresholds are factory-trimmable between
2.2V and 3.08V in steps of approximately 100mV.
3 Applications
Each device of the AS1901/2/3 family is offered with four
time-out periods of 5/20/100/500ms.
Computers
The extremely low current consumption of only 230nA
(typ) at 3.3V makes the device ideal for use in portable
applications.
Intelligent Instruments
Controllers
All devices are available in a 3-pin SOT23 package.
Critical Microprocessor and Microcontroller
Power Monitoring
Portable/Battery-Powered Equipment
Automotive
Figure 1. Functional Block Diagrams
VCC
VCC
3
3
VDD
VCC
VDD
VCC
AS1901
AS1902
Microprocessor
Microprocessor
AS1903
2
2
RESETN,
RESET
RESET
GND
RESETN
RESET I/O
GND
GND
GND
1
1
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