Microchip MCP130-450DI/TO Supervisor Circuit: Features and Application Design Guide
Introduction
In the realm of embedded systems and electronic design, ensuring a controlled and reliable startup and operation for a microcontroller (MCU) is paramount. Power supply fluctuations, brownouts, or glitches can cause a MCU to behave unpredictably, leading to system failures. This is where a dedicated supervisor circuit, or voltage supervisor, becomes an indispensable component. The Microchip MCP130-450DI/TO is a robust and simple solution designed to monitor power supply voltages and provide a reset signal to the MCU, guaranteeing a safe and known startup state. This article explores its key features and provides essential guidance for its application in circuit design.
Key Features of the MCP130-450DI/TO
The MCP130 series offers a range of fixed voltage thresholds, with the MCP130-450DI/TO specifically tailored for 4.50V monitoring. Its feature set is optimized for simplicity and reliability:
1. Precise Voltage Monitoring: The core function of the IC is to monitor the VDD supply line. It asserts a reset signal whenever VDD falls below the precise 4.50V threshold, ensuring the MCU remains in a safe reset state during insufficient power conditions.
2. Manual Reset Input: A critical feature is the Manual Reset (MR) input pin. This allows an external switch, another IC, or a logic signal to forcibly assert the reset signal. This is invaluable for debugging, user-initiated hard resets, or allowing a system manager to trigger a restart.
3. Open-Drain Output: The reset output (/RESET) is an open-drain configuration. This provides significant design flexibility, as it allows the output to be pulled up to a voltage level different from the MCP130's own VDD. This is essential for interfacing with MCUs that operate at lower logic levels (e.g., 3.3V or 1.8V) while the supervisor is powered from a higher voltage rail (e.g., 5V).
4. Hysteresis: The device incorporates built-in hysteresis (typically 80mV). This prevents oscillation of the reset signal when the power supply voltage hovers near the trip point, ensuring a clean and stable reset release once VDD has risen sufficiently above the threshold.
5. Low Power Consumption: The MCP130 operates with very low quiescent current, minimizing its impact on the overall system's power budget, which is crucial for battery-powered applications.
6. Robust Packaging: The TO-92-3 package (DI/TO) is a through-hole package known for its durability and ease of prototyping, making it suitable for a wide range of environments and development stages.
Application Design Guide
Integrating the MCP130-450DI/TO into a design is straightforward, but attention to detail ensures optimal performance.
1. Basic Connection:
Connect VDD to the power supply rail you wish to monitor (e.g., the 5V rail).
Connect GND to the common ground.
Connect the /RESET output pin to the active-low reset pin of your MCU.
Use a pull-up resistor (a value between 1kΩ and 10kΩ is typical) on the /RESET line to the logic voltage level required by the MCU's reset pin. This voltage can be the same as VDD or a different voltage, thanks to the open-drain output.
2. Utilizing the Manual Reset:
The MR pin is active-low. To use it, connect one terminal of a push-button switch to the MR pin and the other terminal to ground.
A debouncing capacitor (e.g., 100nF) and a series resistor (e.g., 1kΩ) can be added between the switch and the MR pin to suppress contact bouncing, though it is often not strictly necessary for a manual reset function.
The MR pin has an internal pull-up, so leaving it unconnected will default to a logic high (inactive) state.
3. Layout Considerations:
Place the MCP130-450DI/TO as close as possible to the MCU's reset pin. This minimizes the length of the reset trace, reducing its susceptibility to noise and electromagnetic interference (EMI) which could cause false resets.
Use decoupling capacitors (e.g., 100nF) on the VDD pin, placed close to the device, to filter high-frequency noise on the power line.
4. Selecting the Right Variant: The MCP130 family includes variants with different trip voltages (e.g., 2.93V, 4.00V, 4.32V, 4.63V). Ensure you select the MCP130-450DI/TO for a 4.50V trip point. If your MCU requires monitoring a different voltage, choose the appropriate part number.
The Microchip MCP130-450DI/TO stands out as an exceptionally reliable and straightforward solution for microcontroller power supervision. Its combination of a precise 4.50V threshold, manual reset capability, and flexible open-drain output makes it a versatile choice for a vast array of 5V-based embedded systems. By following simple design practices, engineers can significantly enhance the robustness and field reliability of their products, preventing erratic behavior and ensuring a controlled system state from power-on through operation.
Keywords: Voltage Supervisor, Microcontroller Reset, Open-Drain Output, Brownout Protection, Power Management
