SBOS508A December   2009  – December 2015 INA129-EP

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
      1. 7.4.1 Noise Performance
      2. 7.4.2 Input Common-Mode Range
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Setting the Gain
        2. 8.2.2.2 Dynamic Performance
        3. 8.2.2.3 Offset Trimming
        4. 8.2.2.4 Input Bias Current Return Path
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Low Voltage Operation
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Community Resources
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

7 Detailed Description

7.1 Overview

The INA129-EP instrumentation amplifier is a type of differential amplifier that has been outfitted with input protection circuit and input buffer amplifiers, which eliminate the need for input impedance matching and make the amplifier particularly suitable for use in measurement and test equipment. Additional characteristics of the INA129-EP include a very low DC offset, low drift, low noise, very high open-loop gain, very high common-mode rejection ratio, and very high input impedances. The INA129-EP is used where great accuracy and stability of the circuit both short and long-term are required.

7.2 Functional Block Diagram

INA129-EP fbd_bos501.gif

7.3 Feature Description

The INA129-EP device is a low power, general-purpose instrumentation amplifier that offers excellent accuracy. The versatile three-operational-amplifier design and small size make the amplifier ideal for a wide range of applications. Current-feedback input circuitry provides wide bandwidth, even at high gain. A single external resistor sets any gain from 1 to 10,000. The INA129-EP device is laser trimmed for very low offset voltage (50 μV) and high common-mode rejection (93 dB at G ≥ 100). This device operates with power supplies as low as ±2.25 V, and quiescent current of 2 mA, typically. The internal input protection can withstand up to ±40 V without damage.

7.4 Device Functional Modes

A single external resistor sets the any gain from 1 to 10000. TI INA129-EP provides an industry standard gain equation, as highlighted in Figure 16.

7.4.1 Noise Performance

The INA129-EP provides very low noise in most applications. Low frequency noise is approximately 0.2 μVPP measured from 0.1 Hz to 10 Hz (G ≥ 100). This provides dramatically improved noise when compared to state-of-the-art chopper-stabilized amplifiers.

INA129-EP vnoise_bos501.gif
G ≥ 100
Figure 15. 0.1-Hz to 10-Hz Input-Referred Voltage Noise

7.4.2 Input Common-Mode Range

The linear input voltage range of the input circuitry of the INA129-EP is from approximately 1.4 V below the positive supply voltage to 1.7 V above the negative supply. As a differential input voltage causes the output voltage increase, however, the linear input range will be limited by the output voltage swing of amplifiers A1 and A2. So the linear common-mode input range is related to the output voltage of the complete amplifier. This behavior also depends on supply voltage (see Figure 5 and Figure 6).

Input-overload can produce an output voltage that appears normal. For example, if an input overload condition drives both input amplifiers to their positive output swing limit, the difference voltage measured by the output amplifier will be near zero. The output of A3 will be near 0 V even though both inputs are overloaded.