AS1923 Datasheet, PDF (1/2 Pages) ams AG – Quad-Voltage Microprocessor Supervisory Circuit

AS1923
Product Brief
Quad-Voltage Microprocessor Supervisory Circuit
1 General Description
The AS1923 microprocessor supervisory circuit was
designed to monitor up to four system supply voltages
without the need for external components, and asserts a
single reset if any of the monitored supply voltages
drops below its reset threshold.
The AS1923 features an active-low reset output that is
asserted when any of the 4 monitored voltages are
below their respective reset threshold. The reset output
is open-drain with a weak internal pullup (10µA) to IN2.
Reset remains low for a specified reset timeout period
(120ms min) after all voltages have stabilized. The out-
put is valid as long as the IN1 or IN2 input voltage
remains >1V.
Minimal external component requirements, small size,
and wide temperature range (-40 to +85°C) greatly
improves reliability compared to individual supervisory
circuits or discrete components.
A wide range of factory-trimmed threshold voltages are
available to accommodate many different supply volt-
ages/tolerances with minimal external component
requirements.
Factory-trimmed options are available for monitoring
+5.0, +3.3, +3.0, +2.5, +1.8, and -5.0V supplies with -5%
and/or -10% tolerances. The device is also available
with one or two user-adjustable threshold options (via
external resistor-divider network) if non-standard voltage
thresholds are required.
The AS1923 is available in an 6-pin SOT23 package.
2 Key Features
! Simultaneous Quad-Voltage Monitoring
! Precision Factory-Trimmed Reset Threshold
Options: +5.0, +3.3, +3.0, +2.5, +1.8, and -5.0V
! User-Adjustable Voltage Monitoring Threshold
Options
! Low Supply Current: 55µA
! Open-Drain – AS1923A
! 10µA Current Source Pullup – AS1923B
! Reset Timeout Period: 120ms
! RESET Valid to IN1 = 1V or IN2 = 1V
! Immune to Fast INx Transients
! External Components not Required
! Guaranteed Performance: Operating Temperature
Range = -40 to +85ºC
! 6-pin SOT23 package
3 Applications
The device is ideal for portable and battery-powered
systems, embedded controllers, intelligent instruments,
automotive systems, critical CPU monitoring, and any
multi-supply application.
Figure 1. Application Diagram and Pinout
Monitoring
4
Voltage 1 _IN1
Monitoring
5
Voltage 2
IN2
3
AS1923
RESETN RESETN
Monitoring
6
Voltage 3 _IN3
Monitoring
1
Voltage 4 _IN4
GND 2
CPU
IN4 1
6 IN3
GND 2 _AS1923 5 IN2
RESETN 3
4 IN1
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