Electronic Design

High-Output Precision Temperature Sensor Delivers High Noise Immunity

The MAX6612 precision analog output temperature sensor features a large change in output voltage with temperature change—19.53 mV/°C—for greater noise immunity than conventional temperature sensors. More importantly, this high delta V/°C supports convenient relationships between temperature and an analog-to-digital converter's (ADC's) digital output.

An 8-bit ADC with a 5-V reference has an LSB value equal to 19.53 mV, the same voltage a 1°C change in the MAX6612's temperature produces. An 8-bit ADC with a 2.5-V reference has an LSB value of 9.765 mV, or 0.5°C. This tracking to the digitization increments in a converter will reduce the interpolation and scale adjustments conventional temperature-sensor ICs require.

A system with the MAX6612 would only need a simple offset adjustment to produce easily digitized temperature values. Other temperature sensors output nonwhole-number relationships between temperature and ADC output data, so the output voltages only align to a quantization interval at a few data points. The intervening data points must be continually recalculated and interpolated for best linearity.

Operating temperature varies with supply voltage. A 2.4-V supply allows the MAX6612 to operate from ­10°C to 70°C. A 3.3-V supply permits operation from ­10°C to 125°C. A 5-V supply enables operation from ­40°C to 150°C.

The MAX6612 is stable when driving large capacitive loads, such as long cables or noise-filtering capacitors, at an ADC's input. Any capacitive load greater than or equal to 1000 pF yields stable operation, which is guaranteed by design. This stability into a large capacitive load permits a wide range of physical configurations, simplifying sensor location.

The MAX6612 comes in a tiny, five-pin SC70 package. Prices start at $0.59 each in 2500-unit quantities. A preliminary data sheet is available online at www.maxim-ic.com/PRGraphics/PRPDF/MAX6612DS.pdf.

Maxim Integrated Products., www.maxim-ic.com; (800) 998-8800.

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