Microchip MCP130T-450I/TT Supervisory Circuit: Features and Application Design Guide
In the realm of embedded systems and digital electronics, ensuring a controlled and reliable startup as well as continuous stable operation is paramount. The Microchip MCP130T-450I/TT is a sophisticated microprocessor supervisory circuit designed specifically to monitor power supply voltages and provide a critical safety net for microcontrollers (MCUs) and other logic devices. This article delves into its key features and offers a practical guide for its application design.
Core Features of the MCP130T-450I/TT
The MCP130T is a member of the MCP130 series of supervisory circuits, renowned for their precision and reliability. The "450" in its part number signifies its fixed voltage threshold of 4.50V, making it ideal for monitoring standard 5V power supplies. The "I/TT" denotes its industrial temperature range (-40°C to +85°C) and its package type (SOT-23).
Its most crucial function is as a voltage supervisor. It continuously monitors the VDD power supply of the host microcontroller. When VDD drops below the 4.50V threshold, the device asserts a reset signal. This reset signal remains asserted until VDD rises above the threshold and remains stable for a minimum period, known as the reset timeout period, which is typically 350ms. This ensures the MCU starts only when the power supply is stable and remains in a known state during brown-out conditions.
A standout feature of this device is its manual reset input (MR). This active-low pin allows an external button or another digital logic signal to force a system reset, providing designers with a simple way to incorporate a user-initiated reset function without additional components.
Furthermore, the MCP130T boasts an extremely low supply current, typically just 5.5 µA, which is negligible for most applications and helps conserve power in battery-operated systems. Its small SOT-23 package makes it perfectly suited for space-constrained PCB designs.
Application Design Guide
Integrating the MCP130T-450I/TT into a design is straightforward, but attention to detail is key for optimal performance.
1. Basic Connection: The typical application circuit is simple. Connect VDD to the system's 5V power rail. Connect the active-low RESET output pin directly to the reset pin of the microcontroller. It is often good practice to include a pull-up resistor (e.g., 10kΩ) on this line, though many modern MCUs have internal pull-ups, making an external one optional. The manual reset (MR) pin can be connected to a tactile switch tied to ground, allowing a user to trigger a reset.
2. Power Supply Decoupling: Place a decoupling capacitor (100nF to 1µF) as close as possible to the VDD and GND pins of the MCP130T. This is critical for noise immunity, preventing voltage transients on the power rail from causing false reset signals.
3. Handling the Manual Reset: The MR pin is internally pulled high. To use it, connect a normally-open switch between the MR pin and ground. When the switch is pressed, it pulls MR low, asserting the reset signal. A small ceramic capacitor (0.1µF) across the switch can help debounce the signal, though the internal timeout period often provides sufficient debouncing.
4. Layout Considerations: Keep the trace from the MCP130T's RESET output to the MCU's reset pin as short as possible to minimize noise pickup and ensure signal integrity. Avoid routing this trace near sources of noise like clock lines or switching power supplies.
5. Selecting the Correct Variant: Microchip offers the MCP130 series with various voltage thresholds (e.g., 2.93V, 3.08V, 4.38V, 4.63V). Ensure you select the MCP130T-450I/TT for 5V systems. For 3.3V systems, a variant like the MCP130T-290I/TT (2.90V threshold) would be more appropriate.
In summary, the MCP130T-450I/TT is an essential component for enhancing system reliability. Its precision voltage monitoring, manual reset capability, and low power consumption make it an excellent choice for a wide array of 5V applications, from industrial control systems to consumer electronics.
ICGOODFIND: The MCP130T-450I/TT from Microchip provides a robust and simple solution for power supervision in 5V systems, ensuring microcontrollers operate only under valid conditions and enhancing overall design integrity.
Keywords: Voltage Supervisor, Brown-Out Protection, Manual Reset, System Reliability, Power Management.
