Microchip MCP120T-315I/TT: A 0V Voltage Supervisor with Open-Drain Output

In the realm of electronic system design, ensuring a controlled and reliable startup and shutdown sequence is paramount for system integrity and data protection. Voltage supervisors, or reset ICs, play a critical role in this process by monitoring the power supply rail and holding the microcontroller in a known state until the supply voltage is stable. The Microchip MCP120T-315I/TT stands out in this category by offering a unique and robust solution, combining a 0V capable voltage supervisor with an open-drain output in an ultra-compact SOT-23 package.

The defining feature of the MCP120T-315I/TT is its ability to operate down to 0V. Unlike many conventional reset circuits that become undefined or lose functionality as VDD drops below 1V, this device continues to assert a valid reset signal even as the supply voltage completely decays to zero. This capability is crucial for applications where a brown-out event could be severe or where the power rail can be completely removed. It guarantees that the system will always be held in a safe reset state, preventing unpredictable microcontroller behavior during power loss and subsequent reapplication of power.

Complementing this feature is its open-drain output configuration. This design offers significant flexibility to the system designer. The open-drain output allows for easy voltage translation and can be pulled up to a voltage rail different from the one being monitored (VDD). This is particularly useful in mixed-voltage systems where the microcontroller's reset pin logic level might be different from the supervisor's supply. Furthermore, multiple open-drain outputs can be wire-OR'd together, enabling the creation of a system-wide reset signal from multiple supervisory circuits monitoring different power rails.

Housed in a SOT-23-3 package, the device is engineered for space-constrained applications. Despite its tiny footprint, it delivers a fixed supervisory threshold of 3.08V (for the -315 variant) with a precision of ±1.5%. The built-in 400ms (min) power-on reset delay ensures the power supply and clock oscillator are fully stable before the microcontroller is released from reset, contributing to overall system reliability.

Typical applications are widespread, including but not limited to:

Portable and Battery-Powered Devices: Where brown-out conditions are common as the battery depletes.

Embedded Control Systems: Including automotive, industrial, and consumer electronics.

Intelligent Peripherals: Requiring a reliable and managed power-up sequence.

Motherboards and DSP Systems: For multi-rail power supply monitoring.

ICGOODFIND: The Microchip MCP120T-315I/TT is an exceptionally robust and versatile voltage supervisor. Its 0V operation capability ensures fail-safe behavior under all power conditions, while its open-drain output provides critical design flexibility for complex, multi-rail systems. Its small form factor makes it an ideal choice for modern, space-sensitive electronic designs demanding unwavering reliability.

Keywords: Voltage Supervisor, Open-Drain Output, 0V Operation, Brown-Out Protection, Reset IC.