The LM340SX12 series devices are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Fahrenheit temperature. The LM340SX12 device has an advantage over linear temperature sensors calibrated in degrees Kelvin, because the user is not required to subtract a large constant voltage from its output to obtain convenient Fahrenheit scaling. The LM340SX12 device does not require any external calibration or trimming to provide typical accuracies of ±1/2°F at room temperature and ±1-12°F over a full 50°F to 300°F temperature range. Lower cost is assured by trimming and calibration at the wafer level. The low output impedance, linear output, and precise inherent calibration of the LM340SX12 device makes interfacing to readout or control circuitry especially easy. It can be used with single power supplies or with plus and minus supplies. Because the LM340SX12 device draws only 75 μA from its supply, the device has very low self-heating, less than 0.2°F in still air.
The LM340SX12 device is rated to operate over a 50°F to 300°F temperature range, while the LM34C is rated for a 40°F to 230°F range (0°F with improved accuracy). The LM340SX12 devices are series is available packaged in hermetic TO-46 transistor packages; while the LM34C, LM34CA, and LM34D are available in the plastic TO-92 transistor package. The LM34D device is available in an 8-lead, surface-mount, small-outline package. The LM340SX12 device is a complement to the LM35 device (Centigrade) temperature sensor.
Feature
- Calibrated Directly in Degrees Fahrenheit
- Linear 10.0 mV/°F Scale Factor
- 1.0°F Accuracy Assured (at 77°F)
- Rated for Full 50° to 300°F Range
- Suitable for Remote Applications
- Low Cost Due to Wafer-Level Trimming
- Operates From 5 to 30 Volts
- Less Than 90-μA Current Drain
- Low Self-Heating, 0.18°F in Still Air
- Nonlinearity Only ±0.5°F Typical
- Low-Impedance Output, 0.4 Ω for 1-mA Load
