AS1901, AS1902, AS1903
Ultra Low-Power µP Supervisory Circuit
Data Sheet
www.austriamicrosystems.com Revision 1.51 1 - 9
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
!
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
3 Applications
The devices are ideal for computers, intelligent instru-
ments, controllers, critical microprocessor and micro-
controller, power monitoring and portable/battery-
powered equipment.
VCC
AS1903
Microprocessor
VDD
GND GND
RESETN RESET I/O
VCC
1
2
3
VCC
AS1901
AS1902
Microprocessor
VDD
GND GND
RESETN,
RESET
RESET
V
CC
1
2
3
