|
Analog Devices (ADI) has introduced a new 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. Thermocouple systems provide accurate and reliable temperature measurements and control, are cost-effective, and can measure a wide range of temperatures.
To achieve good measurement performance cold junction compensation and a high gain accuracy precision amplifier are required and the AD8494, AD8495, AD8496 and AD8497 thermocouple amplifiers look to address this issue by featuring on-chip cold junction compensation that automatically adjusts the thermocouple output for changes in ambient temperature. This feature greatly simplifies the design process and reduces system cost relative to similar discrete solutions.
The four new precision thermocouple amplifiers each convert the small voltages generated by a thermocouple junction into a 5 mV/°C analogue signal that can easily be read by an ADC (analog-to-digital converter) or microcontroller. The integrated cold junction compensation ensures accurate measurement over a wide range of ambient temperatures while the high common-mode rejection (0.1°C/V) allows the AD849x to reject common-mode noise that may be associated with long lead thermocouples.
The AD849x thermocoupler amplifiers operate off a wide variety of voltages, from single 2.7-V to dual ±18-V supplies and are very power efficient, consuming only 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.
With a single 5-V supply, the AD849x amplifiers can cover nearly 1,000-degrees of a thermocouple’s temperature range. A reference pin allows for level shifting of the 0°C output so that negative temperatures can easily be measured, even on a single supply.
Key features and benefits
- Integrated cold junction compensation
- 5-mV/°C output with single-supply operation down to 2.7 V and rail-to-rail output
- High-impedance differential input
- Reference pin allows offset adjustment
- Wide power-supply range: 2.7 V to ±18 V
- High Gain Accuracy – 0.1%
- Low power: 180 µA quiescent supply current
- Low cost: less than US$1.00, in volume
- Lead-free MSOP-8 package
- •New compact broadband amplifier operates across 0.5 GHz - 2.5 GHz frequency range
- •As the semiconductor market shifts into higher gear so the risk of counterfeits rises
- •Rutronik stocking compact thick film resistor with 1100 W power rating from Vishay
- •DLP Technology keeps Texas Instruments at top of MEMS market
