Precision thermocouple amplifier with integrated cold junction compensation provides accurate temperature measurement

Beijing, June 1, 2010-Analog Devices, Inc. (NYSE: ADI), the world's leading high-performance signal processing solution provider and signal conditioning technology leader, has recently been widely used in industrial, commercial and scientific fields K-type and J-type thermocouples for temperature measurement, launched a series of low-cost precision thermocouple amplifiers. The thermocouple system can provide accurate and reliable temperature measurement and control functions, which is cost-effective and has a wide temperature measurement range. However, in order to achieve good measurement performance, cold junction compensation and high gain precision precision amplifiers are essential. ADI's thermocouple amplifiers AD8494, AD8495, AD8496, and AD8497 have been specifically developed to address this issue. They have an on-chip cold junction compensation function that automatically adjusts the thermocouple output based on changes in ambient temperature.
Bob Woskow, president of Robert Marshall and Associates, an embedded microcontroller design and development consulting company based in Encino, California, said: "We use ADI thermocouple amplifiers to design ultrapure heating controllers for industrial applications. ADI ’s amplifiers are small in size and have internal cold junction compensation, so they are very easy to use and require no or only a few other components on the printed circuit board. They are also capable of doing all the work required for thermocouple amplifiers. ”

The four new precision thermocouple amplifiers can convert the small voltage generated by the thermocouple junction into a 5mV / degree Celsius analog signal that is easy to read by an ADC (analog-to-digital converter) or microcontroller. The integrated cold junction compensation function ensures that the thermocouple can achieve accurate measurement in a wide ambient temperature range. The high common mode rejection performance (0.1 degrees Celsius / V) allows the AD849x to suppress the common mode noise that long lead thermocouples may have. The AD849x thermocouple amplifier can be powered by a variety of power supplies from a single 2.7V power supply to ± 18V dual power supplies, and its power efficiency is extremely high, with a quiescent power supply current of only 180uA. When operating with a single power supply, these amplifiers can be directly interfaced with low-supply voltage ADCs, while higher dual-supply voltages are suitable for industrial systems that require a wide common-mode input range. With a single 5V power supply, the AD849x amplifier can cover a thermocouple temperature range of nearly 1,000 degrees. The 0 ° C output can be level-shifted through the reference pin, so even if a single power supply is used, negative temperature can be easily measured.

Steve Sockolov, Director of Precision Signal Conditioning at ADI, pointed out: “Temperature is the second largest measurement parameter. Systems using ADI ’s linear products can achieve robust, repeatable temperature detection through simple design.

Main characteristics and advantages of thermocouple amplifier
-Integrated cold junction compensation-- 5mV / degree Celsius output, single-supply operation, supply voltage can be as low as 2.7V, and provides rail-to-rail output-- High impedance differential input-- Reference pin provides offset adjustment function-- Wide power supply Voltage range: 2.7V to ± 18V
-High gain accuracy: 0.1%
-Low power consumption: 180μA quiescent supply current-Low cost: bulk purchase price is less than $ 1 / piece-Lead-free MSOP-8 package

Supply, quotation and supporting products

Product Sample Supply Thermocouple Type Reference Junction Temperature Ten Thousand Pieces Order Price Package AD8494 Now J Type 0 Degrees Celsius $ 0.98 / piece 8-Lead -50 Degrees Celsius MSOP
AD8495 now K type 0 degree Celsius $ 0.98 / piece 8-lead -50 degree Celsius MSOP
AD8496 Now J-type 25 ° C $ 0.98 / piece 8-pin -100 ° C MSOP
AD8497 Now K-type 25 ° C $ 0.98 / piece 8-lead -100 ° C MSOP

As part of the signal chain design, the AD8494 / 5/6/7 thermocouple amplifier can work with ADI's precision data converters and reference buffer amplifiers.

About ADI
Analog Devices, Inc. (abbreviated as ADI) regards innovation, performance and excellence as the cultural pillars of the company, and has since grown into one of the most enduring and fast-growing companies in the technology field. ADI is a world-leading supplier of data conversion and signal conditioning technology widely recognized in the industry, with 60,000 customers all over the world, covering all types of electronic equipment manufacturers. As a leading manufacturer of high-performance analog integrated circuits (ICs) for more than 40 years, ADI's products are widely used in analog and digital signal processing. The company is headquartered in Norwood, Massachusetts, with design and manufacturing bases all over the world.

Double-sided PCBs are one of the most common kinds available. While single-sided PCBs have one conductive surface, double-sided PCBs have a conductive layer on each side. A dielectric layer is surrounded by circuit copper layers and solder mask on both sides. Vias allow manufacturers to create traces on both sides that route around each other and connect between layers. Manufacturers use double-sided PCBs for products that need a beginner to intermediate level of circuit complexity. This type of PCB doesn`t offer as much circuit complexity or density as multilayer PCBs, but they work as an affordable option in numerous applications