Overview
The LM335A is a precision integrated circuit temperature sensor produced by Texas Instruments. It operates as a 2-terminal zener diode with a breakdown voltage directly proportional to absolute temperature, making it highly accurate for temperature sensing applications. The device is calibrated to the Kelvin temperature scale, providing an output voltage of 10 mV/°K. This linear output and low dynamic impedance make it easy to interface with readout or control circuitry.
The LM335A is part of the LMx35 series, which includes the LM135, LM235, and their 'A' variants. These devices are known for their high accuracy, ease of calibration, and wide operating temperature ranges.
Key Specifications
| Parameter | Test Conditions | Unit | MIN | TYP | MAX |
|---|---|---|---|---|---|
| Operating Temperature Range | Continuous | °C | -40 | 100 | |
| Forward Current | mA | 0.4 | 1 | 5 | |
| Operating Output Voltage | TC = 25°C, IR = 1 mA | V | 2.92 | 2.98 | 3.04 |
| Uncalibrated Temperature Error | TC = 25°C, IR = 1 mA | °C | 1 | 3 | 6 |
| Temperature Error with 25°C Calibration | TMIN ≤ TC ≤ TMAX, IR = 1 mA | °C | 0.5 | 1 | 2 |
| Dynamic Impedance | IR = 1 mA | Ω | 0.5 | 0.6 | |
| Output Voltage Temperature Coefficient | mV/°C | 10 |
Key Features
- Directly Calibrated to the Kelvin Temperature Scale: The LM335A's output voltage is directly proportional to absolute temperature at 10 mV/°K.
- High Accuracy: Available with 1°C initial accuracy, and when calibrated at 25°C, it has typically less than 1°C error over a 100°C temperature range.
- Low Dynamic Impedance: Less than 1-Ω dynamic impedance, allowing the device to operate over a current range of 400 μA to 5 mA with minimal change in performance.
- Easily Calibrated: Includes an easy method for one-point calibration using the ADJ pin to correct for inaccuracies over the full temperature range.
- Wide Operating Temperature Range: Operates from -40°C to 100°C, making it suitable for a variety of applications.
- Low Cost: Offers a cost-effective solution for precision temperature sensing.
Applications
- Power Supplies: Used in temperature monitoring and control within power supply systems.
- Battery Management: Monitors temperature in battery management systems to ensure optimal performance and safety.
- HVAC Systems: Employed in heating, ventilation, and air conditioning systems for precise temperature control.
- Appliances: Integrated into various household and industrial appliances for temperature sensing and control.
Q & A
- What is the operating temperature range of the LM335A?
The LM335A operates over a temperature range of -40°C to 100°C.
- How is the LM335A calibrated for higher accuracy?
The LM335A can be calibrated using a one-point calibration method with the ADJ pin to correct for inaccuracies over the full temperature range.
- What is the dynamic impedance of the LM335A?
The dynamic impedance of the LM335A is less than 1 Ω.
- What is the output voltage temperature coefficient of the LM335A?
The output voltage temperature coefficient of the LM335A is 10 mV/°C.
- What are the typical applications of the LM335A?
The LM335A is used in power supplies, battery management, HVAC systems, and various appliances for temperature sensing and control.
- What is the recommended forward current range for the LM335A?
The recommended forward current range for the LM335A is from 0.4 mA to 5 mA.
- How does the LM335A handle thermal conditions?
The LM335A requires careful thermal management to ensure accurate temperature readings. This includes ensuring the device is mechanically connected to the surface being measured and avoiding heat sources.
- What is the typical uncalibrated temperature error of the LM335A?
The typical uncalibrated temperature error of the LM335A at 25°C is 1°C to 3°C.
- Can the LM335A be used in safety-critical applications?
No, the LM335A should not be used in safety-critical applications without proper evaluation and validation.
- What are the storage temperature limits for the LM335A?
The storage temperature limits for the LM335A are from -60°C to 150°C.
