Microchip MCP809T-450I/TT 5V Voltage Supervisor Technical Overview

Voltage supervisors, often referred to as microcontroller reset circuits or voltage monitors, are essential components in digital systems, ensuring controlled and reliable operation. The Microchip MCP809T-450I/TT is a prominent example within this category, designed to monitor 5V power supplies and assert a reset signal whenever the supply voltage falls below a predefined threshold. This device is crucial for preventing erratic code execution, data corruption, and system lock-up in applications ranging from consumer electronics to industrial embedded systems.

Housed in a space-saving SOT-23-3 package, the MCP809T-450I/TT offers a compact solution for board-space-constrained designs. Its core function is to monitor the VDD supply voltage. When VDD drops below the fixed factory-set threshold of 4.50V, the device immediately asserts an active-low reset output (/MR). This signal remains asserted until VDD rises back above the threshold voltage and remains stable for a minimum reset timeout period of 140ms (typical). This built-in delay is critical, as it ensures the power supply and system clock have stabilized before the microcontroller is taken out of its reset state, guaranteeing a proper start-up sequence.

A key feature of this supervisor is its manual reset capability. The /MR pin can be driven low by an external signal, such as a push-button switch, to force a system reset independent of the supply voltage. This provides designers and end-users with a reliable method to initiate a system restart on demand. The MCP809T-450I/TT is designed for ultra-low power consumption, drawing a very low quiescent current, which is a vital characteristic for battery-powered and energy-sensitive applications. Furthermore, it is immune to brief negative-going voltage glitches on the supply line, enhancing its noise immunity and preventing false reset signals during transient events.

ICGOOODFIND: The Microchip MCP809T-450I/TT stands out as an exceptionally robust and reliable voltage supervisor for 5V systems. Its integration of a precise voltage monitor, a necessary power-on reset delay, and a manual reset input into a miniature package makes it an ideal choice for ensuring the integrity and predictable performance of countless microcontroller-based designs.

Keywords: Voltage Supervisor, Manual Reset, Reset Timeout, 4.50V Threshold, SOT-23 Package.