Microchip MCP1319MT-29LE/OT Voltage Supervisor: Features and Application Circuits
In the realm of electronic systems, ensuring stable and reliable operation is paramount. Voltage supervisors, also known as voltage monitors or reset ICs, play a critical role in this regard by monitoring the power supply rail and holding a microcontroller (MCU) or processor in a known state during power-up, power-down, or brown-out conditions. The Microchip MCP1319MT-29LE/OT is a prominent member of this essential component category, offering a robust set of features in a compact package.
Key Features of the MCP1319MT-29LE/OT
This specific voltage supervisor is designed for precision and reliability. Its standout characteristics include:
Precise Voltage Monitoring: The `-29` suffix denotes a fixed voltage threshold of 2.93V. This highly accurate threshold is crucial for ensuring the monitored system voltage is adequate before releasing the MCU from reset.
Active-Low Reset Output: The MCP1319MT provides an active-low reset signal (`/RESET`), which is the standard logic level used to initiate a reset on most microcontrollers.
Manual Reset Input: A key feature is the inclusion of a manual reset (MR) input pin. This allows an external switch, a test button, or another digital signal from the system to force a reset, greatly aiding in debugging and user control.
Adjustable Reset Timeout Delay: An external capacitor on the `CRST` pin allows designers to adjust the reset pulse width (typically from 1 ms to over 4 seconds). This ensures the MCU remains in reset long enough for the power supply and clock oscillator to stabilize completely.
Small Form Factor: Available in space-efficient SOT-23-5 and SC-70-5 packages (the `OT` package code typically refers to SOT-23), it is ideal for modern, compact PCB designs.
Low Power Consumption: The device consumes very little quiescent current, making it suitable for both line-powered and battery-sensitive applications.
Typical Application Circuits
The MCP1319MT is straightforward to implement, requiring minimal external components. Two common application circuits are detailed below.
1. Basic Voltage Supervisor with Manual Reset
This is the most common configuration for monitoring a microcontroller's VDD supply.
How it works:
The VDD pin is connected directly to the MCU's power rail.
The `/RESET` output is connected to the MCU's active-low reset pin.
The manual reset switch is connected between the `MR` pin and ground. A pull-up resistor (typically 10kΩ to 100kΩ) internal to the IC keeps the `MR` pin high. When the switch is pressed, the pin is pulled low, initiating an immediate reset.
The capacitor `C_DLY` on the `CRST` pin sets the reset timeout period. A value of 1µF typically provides a delay of approximately 100 ms. The reset pulse remains asserted for this fixed period after VDD rises above the threshold or after the manual reset button is released.
2. Monitoring a Secondary Voltage Rail
While often used to monitor the MCU's own supply, the MCP1319 can also supervise a separate, higher-voltage rail (within its absolute maximum ratings, typically up to 5.5V or 6V).
How it works:
The voltage to be monitored (e.g., a 5V system rail) is divided down using resistors R1 and R2 to a level compatible with the MCP1319's VDD pin.
The supervisor's own VDD is powered by the MCU's 3.3V rail. It is crucial that this 3.3V rail is stable before the supervisor attempts to monitor the other rail. The `R1/R2` divider ratio must be calculated so that when the 5V rail is at its minimum valid level, the voltage at the supervisor's VDD pin is still above its own 2.93V threshold. For example, to monitor a 5V rail with a minimum valid level of 4.5V, the divider should be set so that 4.5V (R2/(R1+R2)) ≈ 3.0V.
The `MR` pin can be left floating or pulled up as it is unused in this specific circuit.
The Microchip MCP1319MT-29LE/OT is an exceptionally versatile and reliable voltage supervisor. Its integration of a precise monitor, manual reset capability, and an adjustable timeout delay into a minuscule package makes it an ideal choice for a vast array of embedded systems, from consumer electronics to industrial controls. By providing a guaranteed valid reset signal, it significantly enhances system robustness and prevents unpredictable operation during critical power transitions.
Keywords: Voltage Supervisor, Manual Reset, Reset Timeout Delay, Brown-Out Protection, Microcontroller Reset.
