AS1923 Supervisor IC

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 output is valid as long as the IN1 or IN2 input voltage remains >1V.

Minimal external component requirements, small size, and wide temperature range (-40°C 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 voltages/ tolerances with minimal external component requirements.

Factory-trimmed options are available for monitoring +5.0V, +3.3V, +3.0V, +2.5V, +1.8V, 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 a 6-pin SOT23 package.

Key Features

• Simultaneous Quad-Voltage Monitoring
• Precision Factory-Trimmed Reset Threshold Options:
  +5.0V, +3.3V, +3.0V, +2.5V, +1.8V, 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 =
  -40ºC to +85ºC
• 6-pin SOT23 package

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.

Block diagram for AS1923 Supervisor IC