Microchip TC6215TG-G: A Comprehensive Technical Overview and Application Note
The Microchip TC6215TG-G is a highly precise and versatile temperature switch and sensor designed for system monitoring and protection in a wide array of applications. This device integrates a critical function into a simple, robust package, providing a reliable and cost-effective solution for thermal management without requiring firmware or software development.
Core Technical Specifications and Operation
At its heart, the TC6215TG-G consists of a precision bandgap temperature sensor coupled with a high-gain comparator. Its primary function is to monitor the die temperature and assert a logic output when a user-defined setpoint is exceeded.
Setpoint Programming: The trip point is easily configured using a single external resistor (`R`SET`). This resistor is connected between the `SET` and `GND` pins. The relationship between the resistance and the trip temperature (`T`TRIP`) is linear, allowing for straightforward design-in. Microchip provides detailed curves in the datasheet to select the appropriate resistor value for a desired temperature threshold.
Dual Output Options: The device is offered in two output configurations. The TC6215TG-G features an active-low, open-drain output, which becomes logic low when the temperature rises above the setpoint. This is ideal for interfacing directly with microcontroller reset pins or power management logic. A complementary version with an active-high push-pull output is also available.
Hysteresis: A built-in 5°C of thermal hysteresis is critical for stable operation. It prevents the output from oscillating rapidly when the temperature is very close to the trip point. Once the output is asserted, the temperature must drop by 5°C below the trip point before the output de-asserts, ensuring clean switching behavior.
Key Electrical Characteristics:
Wide Supply Voltage Range: 2.7V to 4.5V (3V/3.3V systems)
Low Supply Current: 35 µA (typical)
High Temperature Accuracy: ±2°C (typical at 25°C)
Open-Drain Output can sink 1 mA
Application Circuits and Implementation
The simplicity of the TC6215TG-G is one of its greatest strengths. A basic application circuit requires only three external components: the setpoint resistor (`R`SET`), a power supply decoupling capacitor (typically 0.1 µF), and a pull-up resistor on the open-drain output.
1. System Overheat Protection: The most common use case. The output can be tied to the shutdown or enable pin of a voltage regulator or a power MOSFET, cutting power to a subsystem or the entire board when a critical temperature is reached, thus preventing damage.
2. Microcontroller (MCU) Thermal Reset: Connecting the open-drain output directly to an MCU's active-low reset input (`MRESET`) allows the TC6215 to force a system reset if environmental conditions become too extreme, ensuring software starts from a known state once the board has cooled.
3. Cooling Fan Control: The device can directly drive a small fan or, more commonly, control a transistor that switches the fan on when the temperature threshold is crossed, providing a simple and efficient cooling solution.
4. Temperature Alarm Indicator: The output can drive an LED or a buzzer to provide a visual or audible warning to users of an overheating condition.
Design Considerations and Advantages
Reliability: As a purely hardware-based solution, it is immune to software crashes or locked-up firmware, making it exceptionally reliable for critical protection circuits.
Simplicity vs. MCU-based Solutions: While many modern MCUs have internal temperature sensors, their accuracy can be limited, and they require software to be running. The TC6215 operates independently, offering higher precision for protection duties and functionality even if the main processor fails.
Board Layout: For accurate sensing, the device must be placed as close as possible to the heat source requiring monitoring (e.g., a processor, power amplifier, or voltage regulator).
The Microchip TC6215TG-G stands out as an exceptionally straightforward and robust hardware-based thermal watchdog. Its programmability via a single resistor, low power consumption, and high accuracy make it an indispensable component for designers seeking to enhance system reliability and implement fail-safe thermal protection without complexity.
Keywords:
1. Temperature Switch
2. Thermal Management
3. Setpoint Programming
4. Overheat Protection
5. Open-Drain Output
