Microchip MCP809T-485I/TT 3-Pin Microprocessor Reset Circuit Technical Datasheet Overview

The Microchip MCP809T-485I/TT is a highly reliable, low-power 3-pin microprocessor supervisory circuit designed to monitor power supply voltages in digital systems. It provides a critical reset function to ensure a microcontroller or microprocessor operates correctly during power-up, power-down, and brown-out conditions. Housed in a compact SOT-23 package, this device is engineered for space-constrained applications where board real estate is at a premium.

A key feature of the MCP809T is its precise voltage monitoring. The -485 variant is tailored to monitor a nominal 4.85V VDD supply, asserting a reset signal whenever the supply voltage drops below a predefined threshold. This ensures the connected microprocessor remains in a known safe state, preventing erratic code execution that can occur from undervoltage conditions. The device requires an extremely low supply current, typically just 7.5 µA, making it an excellent choice for battery-powered and portable devices where power conservation is paramount.

The simplicity of its 3-pin design (VDD, GND, and /RESET) allows for easy integration into new and existing designs without complex external components. The active-low open-drain reset output (/RESET) can be connected directly to the microcontroller's reset pin and is capable of driving multiple ICs, providing design flexibility. The MCP809T also features a 140ms min. reset time delay upon VDD rising above the threshold, ensuring the power supply and system clock are stable before the microprocessor begins operation.

Operating over an industrial temperature range of -40°C to +85°C, the MCP809T-485I/TT is built to perform reliably in harsh environmental conditions, suitable for industrial automation, automotive electronics, and consumer applications.

ICGOODFIND: The MCP809T-485I/TT is an efficient and robust solution for system voltage monitoring, offering critical protection with minimal power and space requirements. Its precision and reliability make it an essential component for ensuring the integrity of microprocessor-based systems.

Keywords: Microprocessor Supervisor, Voltage Monitoring, Reset Circuit, Low-Power, Brown-Out Protection.