Microchip MCP809T-270I/TT 3-Pin Microcontroller Reset Circuit Technical Datasheet

Introduction

The Microchip MCP809T-270I/TT is a pivotal component in the realm of embedded systems and electronic design, serving as a dedicated microcontroller supervisor. This 3-pin device is engineered to monitor power supply voltages in digital circuits, ensuring system stability and reliability by providing a reset signal to the microcontroller during power-up, power-down, or brown-out conditions. Its compact SOT-23 package and minimal external component requirement make it an ideal choice for space-constrained applications.

Key Features and Specifications

The MCP809T-270I/TT is designed with a fixed threshold voltage of 2.70V, making it suitable for monitoring 3V and 3.3V power supplies commonly used in modern microcontrollers. The device asserts a reset signal whenever VDD drops below this threshold, holding the reset active for a minimum period after VDD rises above it to ensure the microcontroller starts under stable conditions. This reset timeout period is typically 140ms, providing ample time for the power supply and clock oscillator to stabilize.

A significant advantage of the MCP809T is its ultra-low supply current, typically drawing just 4.5µA. This low power consumption is crucial for battery-powered and energy-sensitive applications, minimizing the overall system drain. The device operates over a wide temperature range of -40°C to +85°C, ensuring reliability in industrial and automotive environments. The open-drain output configuration allows flexibility in interfacing with various microcontroller logic levels.

Functional Description

The MCP809T-270I/TT operates with simplicity and efficiency. Its three pins are VDD (power supply input), GND (ground), and /RESET (active-low reset output). When the monitored VDD voltage falls below the 2.70V threshold, the /RESET output is driven active (low). It remains low for the entire duration the supply is inadequate and for the fixed timeout period after VDD has recovered to a valid level. This guarantees that the connected microcontroller or processor is held in a known safe state until the power is fully stable.

Application Circuits

The typical application circuit is remarkably straightforward, requiring only a single bypass capacitor (typically 0.1µF) placed close to the VDD and GND pins to filter noise. The /RESET output is connected directly to the reset pin of the microcontroller. For systems requiring a pull-up resistor on the reset line, this is incorporated externally, allowing the voltage to be pulled up to a different logic level if necessary, thanks to the open-drain output.

Conclusion

The MCP809T-270I/TT is an essential, robust, and highly reliable solution for power management and microcontroller supervision. Its combination of precise voltage monitoring, low power consumption, and small form factor addresses the core needs of modern electronic designs, from consumer electronics to industrial control systems. By ensuring a controlled and safe reset sequence, it significantly enhances the overall robustness and fault tolerance of embedded applications.

ICGOODFIND: The MCP809T-270I/TT is a superb find for designers seeking a minimalist, high-performance microcontroller reset circuit. It offers exceptional value through its reliability, low current draw, and ease of use, making it a top recommendation for any project requiring dependable power-on-reset functionality.

Keywords: Microcontroller Supervisor, Power-on Reset, Brown-out Detection, Voltage Monitoring, Low-Power Consumption