AS1920 Datasheet, PDF (1/2 Pages) ams AG – Triple-Voltage, Micro-Power Microprocessor Supervisory Circuits

austriamicrosystems
AS1920, AS1922
Triple-Voltage, Micro-Power Microprocessor
Supervisory Circuits
Product Brief
1 General Description
2 Key Features
The AS1920 and AS1922 microprocessor supervisory
circuits were designed to generate a reset when at least
one of the three monitored supply voltages falls below
its respective trip threshold.
These very-low-current (6.5µA, typ) devices maintain
reset for a minimum timeout period after all supplies
have stabilized. Guaranteed to be in the correct state for
VCC > +1.0V, these devices are perfect for multiple-volt-
age systems with low current requirements and strict
monitoring requirements.
The devices are available as the standard products
listed in Table 1.
Table 1. Standard Products
Model Output Type Supervisory Voltages
AS1920-18 Push/Pull
3V, 1.8V, Adjustable
AS1922-18 Open-Drain 3V, 1.8V, Adjustable
! Simultaneous Triple-Voltage Monitoring
! Very-Low Supply Current: 6.5µA
! ±1.5% Accuracy Over Temperature
! Reset Time Delay: 200ms
! Power Supply Transient Immunity
! Guaranteed Reset for VCC3 ≥ 1V or VCC18 ≥ 1V
! Active-Low Push/Pull Reset Output (AS1920)
All devices monitor primary and secondary factory-
trimmed voltages. Additionally, a third monitoring voltage
can be selected via an external resistor divider.
The AS1920 has an active-low push/pull reset output,
whereas the AS1922 has an active-low open-drain reset
output.
The AS1920 and AS1922 are available in a 5-pin
SOT23 package.
Figure 1. Typical Application Diagram
! Active-Low Open-Drain Reset Output (AS1922)
! 5-pin SOT23 Package
3 Applications
The devices are ideal for personal computers, note-
books, battery-powered systems, embedded controllers,
intelligent instruments, automotive systems, critical CPU
monitoring, and any multi-supply monitoring application.
3V
1.8V
2.5V
0.1µF
System
Logic
R1
130kΩ
1%
0.1µF
R2
100kΩ
1%
5
VCC3
4
VCC18
3
VCCA
AS1920/
AS1922
1
RESETN
2
GND
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Revision 0.65
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