Microchip MCP100T-315I/TT Voltage Supervisor: Features and Application Circuits

In modern electronic systems, ensuring reliable operation and system integrity during power-up, power-down, and brownout conditions is critical. The Microchip MCP100T-315I/TT is a pivotal component designed specifically for this purpose. This voltage supervisor, or microprocessor reset controller, provides a robust solution for monitoring power supply voltages and generating a reset signal to the microcontroller or CPU when the supply voltage falls below a predefined threshold. This article delves into the key features of this device and explores several practical application circuits.

Key Features of the MCP100T-315I/TT

The MCP100T-315I/TT is a member of Microchip's extensive family of voltage supervisors. It is characterized by its precise 3.15V threshold voltage, making it ideally suited for monitoring 3.3V power supply rails, which are ubiquitous in contemporary digital electronics. One of its most significant advantages is its extremely low supply current, typically drawing just 4.5 µA. This minimal power consumption is crucial for battery-powered and energy-sensitive applications.

The device is offered in a space-saving SOT-23-3 package, facilitating its use in compact PCB designs. It features an active-low, open-drain reset output, which provides design flexibility by allowing the use of an external pull-up resistor to the desired logic voltage level. This output remains asserted while VDD is below the threshold and for a minimum period after VDD rises above it, ensuring the connected microprocessor starts from a known state. Furthermore, the MCP100T is designed to be stable with or without a bypass capacitor at its VDD pin, simplifying the board layout and reducing component count.

Application Circuits

The primary function of the MCP100T is to monitor a single voltage rail. The basic application circuit is remarkably straightforward.

1. Basic Microprocessor Reset Circuit:

The most common application is generating a reset signal for a microprocessor. The VDD pin is connected directly to the positive power supply rail (e.g., 3.3V) to be monitored. The GND pin is connected to ground. The open-drain reset output (/RESET) is connected to the MCU's reset pin through a pull-up resistor (typically 10 kΩ). The pull-up resistor can be connected to the same 3.3V rail or to another voltage level compatible with the MCU's reset input requirements. When the 3.3V supply dips below approximately 3.15V, the /RESET output is pulled low, initiating a controlled reset of the microprocessor.

2. Multi-Voltage Level Monitoring:

While the MCP100T monitors a single voltage, its open-drain output allows for easy integration into systems with multiple voltage rails. The /RESET outputs from several supervisors (each monitoring a different voltage, e.g., 3.3V, 2.5V, and 1.8V) can be wire-ANDed together by connecting them to a single pull-up resistor. The combined reset signal sent to the MCU will be asserted low if any of the monitored voltages falls below its respective threshold. This creates a highly reliable system-wide reset mechanism.

3. Manual Reset Extension:

The circuit can be easily modified to include a manual reset button for testing and debugging. A normally-open pushbutton switch is connected between the /RESET node and ground. When the button is pressed, it actively pulls the reset line low, regardless of the state of the power supply, forcing the microprocessor into a reset state.

ICGOOODFIND

ICGOOODFIND: The Microchip MCP100T-315I/TT stands out as an exceptionally efficient and reliable solution for power supply monitoring in 3.3V systems. Its combination of ultra-low power consumption, a small form factor, and design flexibility makes it an indispensable component for ensuring the stability and data integrity of everything from consumer gadgets to industrial equipment. Its simplicity of use and robust performance solidify its position as a go-to choice for engineers.

Keywords:

1. Voltage Supervisor

2. Microprocessor Reset

3. Brown-out Protection

4. Open-Drain Output

5. Low Power Consumption