The MAX812TEUS from Maxim Integrated is a compact, highly efficient microprocessor (µP) supervisory circuit designed to monitor power supplies in µP and digital systems. It provides excellent circuit reliability and low cost by eliminating external components and adjustments when used in systems with +5V-powered µP.

This supervisory circuit significantly enhances system reliability by providing several key protection features. It offers a precision temperature-compensated voltage reference and comparator circuit to monitor the status of the power supply (V<sub>CC). When V<sub>CC falls below the reset threshold, the RESET output is asserted, which remains active until V<sub>CC rises above the reset threshold, plus a reset timeout period. This ensures the system has a proper reset during power-up, power-down, and brown-out conditions.

The MAX812TEUS is available in a 4-pin SOT-143 package, making it suitable for space-constrained applications. It has an active-low RESET output with an open-drain configuration and supports a reset threshold voltage of 4.63V, making it ideal for 5V-powered systems. The device's reset timeout period, typically 140ms, allows sufficient time for the µP and other digital systems to stabilize during power-up.

Key features of the MAX812TEUS include:

• Precision monitoring of +5V power-supply voltages
• Fully specified over temperature
• Available in a small SOT-143 package
• Low supply current of 17µA (typical)
• 140ms min power-on reset pulse width
• Guaranteed RESET output valid to V<sub>CC = 1V
• No external components required

This device is commonly used in computers, controllers, intelligent instruments, critical µP power monitoring, and portable/battery-powered equipment. The MAX812TEUS ensures that the µP is reset properly during power-up, which is critical for the start-up and operation of digital systems. By integrating this supervisory circuit, designers can enhance system reliability and performance while maintaining cost-effectiveness and minimizing design complexity.