AD8496

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Full J-Type Range 25° to 100° Thermocouple Amplifier w/Cold Junction Compensation

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Overview

  • Low cost and easy to use
  • Pretrimmed for J type thermocouples
  • Internal cold junction compensation
  • High impedance differential input
  • Standalone 5 mV/°C thermometer
  • Reference pin allows offset adjustment
  • Thermocouple break detection
  • See data sheet for additional features.

The AD8494/AD8495/AD8496/AD8497are precision instrumentation amplifiers with thermocouple cold junction compensators on an integrated circuit. They produce a high level (5 mV/°C) output directly from a thermocouple signal by combining an ice point reference with a precalibrated amplifier. They can be used as standalone thermometers or as switched output setpoint controllers using either a fixed or remote setpoint control.

The AD8494/AD8495/AD8496/AD8497 can be powered from a single-ended supply (less than 3 V) and can measure temperatures below 0°C by offsetting the reference input. To minimize self-heating, an unloaded AD849x typically operates with a total supply current of 180 μA, but it is also capable of delivering in excess of ±5 mA to a load.

The AD8494 and AD8496 are precalibrated by laser wafer trimming to match the characteristics of J type (iron-constantan) thermocouples; the AD8495 and AD8497 are laser trimmed to match the characteristics of K type (chromel-alumel) thermo-couples. See Table 1 on the data sheet for the optimized ambient temperature range of each part.

The AD8494/AD8495/AD8496/AD8497 allow a wide variety of supply voltages. With a 5 V single supply, the 5 mV/°C output allows the devices to cover nearly 1000 degrees of a thermo-couple’s temperature range.

The AD8494/AD8495/AD8496/AD8497 work with 3 V supplies, allowing them to interface directly to lower supply ADCs. They can also work with supplies as large as 36 V in industrial systems that require a wide common-mode input range.

Product Highlights

  1. Complete, precision laser wafer trimmed thermocouple signal conditioning system in a single IC package.
  2. Flexible pinout provides for operation as a setpoint controller or as a standalone Celsius thermometer.
  3. Rugged inputs withstand 4 kV ESD and provide over-voltage protection (OVP) up to VS ± 25 V.
  4. Differential inputs reject common-mode noise on the thermocouple leads.
  5. Reference pin voltage can be offset to measure 0°C on single supplies.
  6. Available in a small, 8-lead MSOP that is fully RoHS compliant.

Applications

  • J type thermocouple temperature measurement
  • Setpoint controller
  • Celsius thermometer
  • Universal cold junction compensator
  • White goods (oven, stove top) temperature measurements
  • Exhaust gas temperature sensing
  • Catalytic converter temperature sensing

AD8496
Full J-Type Range 25° to 100° Thermocouple Amplifier w/Cold Junction Compensation
AD8494-8495-8496-8497 Functional Block Diagram AD8494-8495-8496-8497 Pin Configuration
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Evaluation Kits

eval board
EVAL-AD8496

AD8496 Evaluation Board

Features and Benefits

  • J type thermocouple (provided)
  • Low cost
  • Pretrimmed for J type thermocouple
  • Internal cold junction compensation
  • Reference pin allows offset adjustment

Product Details

This user guide is a description of functionality for the AD8494 series evaluation board. The evaluation board can be configured for the AD8494, AD8495, AD8496, and AD8497 to ensure that the metals and alloys are properly matched for the thermocouple type for which the device is trimmed. The 4-layer evaluation board is designed to allow users to quickly prototype the precision thermocouple amplifiers for various user defined configurations for different applications. The evaluation board has three modes of operation: linear mode, setpoint controller mode, and hysteresis on setpoint controller mode.

The AD8494/AD8495/AD8496/AD8497 data sheet is available at www.analog.com. This data sheet provides additional information on the AD8494, AD8495, AD8496, and AD8497 and must be consulted in conjunction with this user guide when using the evaluation board.

EVAL-AD8496
AD8496 Evaluation Board
AD849x Evaluation Board AD849x Evaluation Board - Bottom View AD849x Evaluation Board - Top View

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