Date: 27/05/2010

4 new thermocouple amplifiers from ADI for K and J type thermocouples

Analog Devices has introduced the AD8494, AD8495, AD8496 and AD8497, a series of low-cost, precision thermocouple amplifiers for K- and J-type thermocouples, which are widely used to measure temperature in industrial, commercial, and scientific applications.

The AD8494, AD8495, AD8496 and AD8497 thermocouple amplifiers feature on-chip cold junction compensation that automatically adjusts the thermocouple output for changes in ambient temperature.

"We're using ADI's thermocouple amplifiers in designs for ultra-pure heating controllers for industrial applications," said Bob Woskow, president, Robert Marshall and Associates, an Encino, California-based embedded microcontroller design and development consultancy. "ADI's amplifiers are smaller, complete with internal cold junction compensation and thus are quite simple to use with few or no additional parts needed on the printed circuit board. They will do everything we need a thermocouple amplifier to do."

These new precision thermocouple amplifiers convert the small voltages generated by a thermocouple junction into a 5 mV/deg C analog signal that can easily be read by an ADC (analog-to-digital converter) or microcontroller. Its high common-mode rejection (0.1°C/V) allows the AD849x to reject common-mode noise that may be associated with long lead thermocouples. These thermocouple amplifiers operate off a variety of voltages, from single 2.7-V to dual ±18-V supplies and are very power efficient, consuming 180 uA quiescent supply current. In single-supply operation the amplifiers can directly interface to lower-supply ADCs while higher, dual-supply voltages can be used for industrial systems that require a wide common mode input range. ADI says that the amplifiers can cover nearly 1,000-degrees of a thermocouple's temperature range with a single 5-V supply. It also has a reference pin that allows for level shifting of the 0deg C output so that negative temperatures can easily be measured, even on a single supply.

"Temperature is the second most measured parameter. Systems using ADI's linear products provide rugged, repeatable temperature sensing with simplified design," said Steve Sockolov, director, Precision Signal Conditioning Group, Analog Devices. "Integrated cold junction compensation greatly simplifies thermocouple system design for use in all applications including medical dialysis machines, blood analyzers, process control and instrumentation."

Product Sample
Availability Thermocouple
Type
Range Reference
Junction Price Each
Per 10K Packaging
AD8494 NOW J-Type 0°C - 50°C $0.98 8-lead MSOP
AD8495 NOW K-Type 0°C - 50°C $0.98 8-lead MSOP
AD8496 NOW J-Type 25°C - 100°C $0.98 8-lead MSOP
AD8497 NOW K-Type 25°C - 100°C $0.98 8-lead MSOP




For more information visit: http://www.analog.com