The CAT809S is a supervisory circuit that monitors the voltage level of a power supply and provides a reset signal to a microcontroller or microprocessor when the voltage drops below a specified threshold. Manufactured by Catalyst Semiconductor, it's designed for reliable operation in a variety of applications.

Applications

• Microcontroller reset circuitry
• Battery-powered devices
• Embedded systems
• Industrial control equipment
• Consumer electronics

Features

• Precision voltage monitoring
• Active-low reset output
• Open-drain reset output
• Internal pull-up resistor (some versions)
• Small package size (SOT-23 or similar)
• Low supply current

Benefits

• Reliable reset signal ensures proper system initialization after a power failure or voltage drop.
• Prevents data corruption by resetting the microcontroller before it can operate with insufficient voltage.
• Simplifies system design by integrating voltage monitoring and reset functionality into a single chip.
• Low power consumption extends battery life in portable applications.
• Compact package allows for use in space-constrained designs.

Additional Details

The CAT809S monitors the input voltage and asserts a reset signal when the voltage falls below the threshold. The reset output remains active until the voltage rises above the threshold plus a hysteresis voltage. This hysteresis prevents oscillations around the threshold voltage. The device is typically available in a small SOT-23 package. The CAT809S requires minimal external components, simplifying system design. The reset output is an open-drain output, which allows for multiple supervisory circuits to be connected in parallel. It's commonly used in applications where data integrity and reliable system operation are critical.