The **LM26CIM5-RPA/NOPB** is a precision, single-chip, factory-programmed thermostat (temperature switch) manufactured by Texas Instruments. It is designed to trigger a digital output when a specific temperature threshold is reached. --- ## 1. Core Technical Specifications The following table summarizes the key electrical and physical characteristics: | Parameter | Specification | | :--- | :--- | | **Function** | Factory-Preset Thermostat / Temperature Switch | | **Trip Temperature** | Fixed (Pre-programmed) - Typically specific to the suffix | | **Operating Voltage** | 2.7V to 5.5V | | **Supply Current** | 16 µA (typical) / 40 µA (max) | | **Output Type** | Open-Drain (Active Low) | | **Accuracy** | ±3°C (Max) from -25°C to 110°C | | **Hysteresis** | 2°C or 10°C (Fixed internally) | | **Package** | SOT-23-5 (Small Outline Transistor) | --- ## 2. Pin Configuration (SOT-23-5) Understanding the pinout is essential for PCB design: 1. **HYST (Pin 1):** Hysteresis control pin. Connecting to V+ or GND selects between different hysteresis levels (usually 2°C or 10°C). 2. **GND (Pin 2):** Ground. 3. **V+ (Pin 3):** Positive supply voltage. 4. **T_DET (Pin 4):** Digital Output. This is an open-drain output that pulls low when the trip temperature is exceeded. 5. **VTEMP (Pin 5):** Analog Output. Provides a voltage proportional to the current temperature (approx. -6.2 mV/°C). --- ## 3. Key Features & Functionality ### Open-Drain Output The **T_DET** pin requires a pull-up resistor to a logic voltage (which can be different from the V+ supply, up to 5.5V). This makes it ideal for interfacing with microcontrollers or directly driving a small MOSFET for fan control. ### Factory Programming The "RPA" in the part number signifies the specific temperature trip point and output logic configuration set at the factory. * **Trip Point:** Typically represents a specific temperature (e.g., 45°C, 65°C, etc.). * **Response:** In this specific "RPA" configuration, the output transitions when the temperature rises above the setpoint. ### Analog Monitoring Unlike simple thermal switches, this part also provides the **VTEMP** analog output. This allows a system to not only react to a "critical" heat event but also monitor the actual temperature via an ADC (Analog-to-Digital Converter). --- ## 4. Typical Application Circuit ```mermaid graph LR VCC[+5V] --- R1[Pull-up Resistor] R1 --- Pin4[T_DET Pin 4] Pin4 --- MCU[Microcontroller Input] VCC --- Pin3[V+ Pin 3] GND --- Pin2[GND Pin 2] ``` ---