austriamicrosystems AG is now ams AG The technical content of this austriamicrosystems datasheet is still valid. Contact information: Headquarters: ams AG Tobelbaderstrasse 30 8141 Unterpremstaetten, Austria Tel: +43 (0) 3136 500 0 e-Mail: ams sales ams.com Please visit our website at www.ams.com Datasheet AS1923 Quad-Voltage Microprocessor Supervisory Circuit 1 General Description 2 Key Features Simultaneous Quad-Voltage Monitoring The AS1923 microprocessor supervisory circuit was designed to monitor up to four system supply voltages without the need for exter- Precision Factory-Trimmed Reset Threshold Options: +5.0, nal components, and asserts a single reset if any of the monitored +3.3, +3.0, +2.5, +1.8, and -5.0V supply voltages drops below its reset threshold. User-Adjustable Voltage Monitoring Threshold Options The AS1923 features an active-low reset output that is asserted Low Supply Current: 55A when any of the 4 monitored voltages are below their respective reset threshold. The reset output is open-drain with a weak internal Open-Drain AS1923A pullup (10A) to IN2. Reset remains low for a specified reset timeout 10A Current Source Pullup AS1923B period (120ms min) after all voltages have stabilized. The output is valid as long as the IN1 or IN2 input voltage remains >1V. Reset Timeout Period: 120ms Minimal external component requirements, small size, and wide tem- RESET Valid to IN1 = 1V or IN2 = 1V perature range (-40 to +85C) greatly improves reliability compared Immune to Fast INx Transients to individual supervisory circuits or discrete components. External Components not Required A wide range of factory-trimmed threshold voltages are available to accommodate many different supply voltages/tolerances with mini- Guaranteed Performance: Operating Temperature Range = -40 mal external component requirements. to +85C Factory-trimmed options are available for monitoring +5.0, +3.3, 6-pin SOT23 Package +3.0, +2.5, +1.8, and -5.0V supplies with -5% and/or -10% toler- ances. The device is also available with one or two user-adjustable threshold options (via external resistor-divider network) if non-stan- dard voltage thresholds are required. The AS1923 is available in an 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. AS1923 - Typical Application Monitoring 4 Voltage 1 IN1 5 Monitoring Voltage 2 3 IN2 CPU AS1923 RESETN RESETN Monitoring 6 Voltage 3 IN3 Monitoring 1 Voltage 4 IN4 GND 2 www.austriamicrosystems.com/Supervisors/AS1923 Revision 1.01 1 - 16 ams AG Technical content still valid