Overview
The LM34DMX/NOPB, produced by Texas Instruments, is a precision integrated-circuit temperature sensor. This device is calibrated directly in degrees Fahrenheit, eliminating the need for users to subtract a large constant voltage to obtain Fahrenheit scaling. The LM34 series devices are known for their high accuracy, requiring no external calibration or trimming, and they provide typical accuracies of ±1/2°F at room temperature and ±1-1⁄2°F over a full −50°F to 300°F temperature range. The low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry particularly easy. The device operates from a supply voltage of 5 to 30 volts and draws only 75 µA, resulting in very low self-heating of less than 0.2°F in still air.
Key Specifications
| Parameter | Conditions | Unit | Min | Max | |
|---|---|---|---|---|---|
| Accuracy at 77°F | TA = 77°F | °F | ±0.4 | ±0.4 | ±0.4 |
| Accuracy over Full Range | −50°F ≤ TJ ≤ 300°F | °F | ±1-1⁄2 | ||
| Scale Factor | mV/°F | 10.0 | |||
| Supply Voltage | V | 5 | 30 | ||
| Current Drain | VS = 5 V, TA = 77°F | µA | 75 | 90 | |
| Output Impedance | For 1-mA Load | Ω | 0.4 | ||
| Self-Heating | In Still Air | °F | < 0.2 | ||
| Nonlinearity | Over Rated Temperature Range | °F | ±0.5 |
Key Features
- Calibrated Directly in Degrees Fahrenheit: No need to subtract a large constant voltage to obtain Fahrenheit scaling.
- Linear 10.0 mV/°F Scale Factor: Output voltage is linearly proportional to the Fahrenheit temperature.
- High Accuracy: ±1/2°F at room temperature and ±1-1⁄2°F over a full −50°F to 300°F temperature range.
- Low Self-Heating: Less than 0.2°F in still air.
- Low Cost: Due to wafer-level trimming and calibration.
- Low Output Impedance: 0.4 Ω for a 1-mA load.
- Low Current Drain: Only 75 µA from the supply.
- Suitable for Remote Applications: Can be used with single power supplies or with plus and minus supplies.
Applications
- Power Supplies: For temperature monitoring and control.
- Battery Management: To monitor battery temperature for optimal performance and longevity.
- HVAC (Heating, Ventilation, and Air Conditioning): For temperature sensing in heating and cooling systems.
- Appliances: In various household and industrial appliances to monitor and control temperature.
Q & A
- What is the temperature range of the LM34?
The LM34 operates over a −50°F to 300°F temperature range.
- What is the scale factor of the LM34?
The output voltage of the LM34 is linearly proportional to the Fahrenheit temperature with a scale factor of 10.0 mV/°F.
- How accurate is the LM34 at room temperature?
The LM34 has an accuracy of ±1/2°F at room temperature.
- What is the supply voltage range for the LM34?
The LM34 operates from a supply voltage of 5 to 30 volts.
- How much current does the LM34 draw from its supply?
The LM34 draws only 75 µA from its supply.
- What is the output impedance of the LM34?
The output impedance of the LM34 is 0.4 Ω for a 1-mA load.
- Is the LM34 suitable for remote applications?
- What are some common applications of the LM34?
The LM34 is commonly used in power supplies, battery management, HVAC systems, and various household and industrial appliances.
- Does the LM34 require external calibration or trimming?
No, the LM34 does not require any external calibration or trimming to provide its specified accuracy.
- How does the LM34 handle capacitive loads?
The LM34 can drive 50 pF without special precautions. For heavier loads, it is recommended to isolate or decouple the load with a resistor or use an R-C damper.
