JAJSEY8A March   2018  – January 2021 OPA197-Q1 , OPA2197-Q1 , OPA4197-Q1

PRODUCTION DATA  

  1. 特長
  2. アプリケーション
  3. 概要
  4. Revision History
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information: OPA197-Q1
    5. 6.5 Thermal Information: OPA2197-Q1
    6. 6.6 Thermal Information: OPA4197-Q1
    7. 6.7 Electrical Characteristics: VS = ±4 V to ±18 V (VS = 8 V to 36 V)
    8. 6.8 Electrical Characteristics: VS = ±2.25 V to ±4 V (VS = 4.5 V to 8 V)
    9. 6.9 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Input Protection Circuitry
      2. 7.3.2 EMI Rejection
      3. 7.3.3 Phase Reversal Protection
      4. 7.3.4 Thermal Protection
      5. 7.3.5 Capacitive Load and Stability
      6. 7.3.6 Common-Mode Voltage Range
      7. 7.3.7 Electrical Overstress
      8. 7.3.8 Overload Recovery
    4. 7.4 Device Functional Modes
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 16-Bit Precision Multiplexed Data-Acquisition System
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curve
      2. 8.2.2 Slew-Rate Limit for Input Protection
      3. 8.2.3 Precision Reference Buffer
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 TINA-TI™ Simulation Software (Free Download)
        2. 11.1.1.2 TI Precision Designs
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 ドキュメントの更新通知を受け取る方法
    4. 11.4 サポート・リソース
    5. 11.5 Trademarks
    6. 11.6 静電気放電に関する注意事項
    7. 11.7 用語集
  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

Capacitive Load and Stability

The OPAx197-Q1 feature a patented output stage capable of driving large capacitive loads, and in a unity-gain configuration, directly drive up to 1 nF of pure capacitive load. Increasing the gain enhances the ability of these amplifiers to drive greater capacitive loads; see #SBOS6207401 and #SBOS6207860. The particular op-amp circuit configuration, layout, gain, and output loading are some of the factors to consider when establishing whether an amplifier is stable in operation.

GUID-1AC7E65C-7B7E-4BFB-AAB1-89494062DA46-low.gifFigure 7-7 Small-Signal Overshoot vs Capacitive Load (100-mV Output Step)
GUID-1C78AA73-4A98-44D2-88F9-BE91190E96C9-low.gifFigure 7-8 Small-Signal Overshoot vs Capacitive Load (100-mV Output Step)

 

For additional drive capability in unity-gain configurations, improve capacitive load drive by inserting a small (10-Ω to 20-Ω) resistor, RISO, in series with the output, as shown in #SBOS6209187. This resistor significantly reduces ringing and maintains dc performance for purely capacitive loads. However, if a resistive load is in parallel with the capacitive load, then a voltage divider is created, thus introducing a gain error at the output and slightly reducing the output swing. The error introduced is proportional to the ratio RISO / RL, and is generally negligible at low output levels. A high capacitive load drive makes the OPAx197-Q1 a great choice for applications such as reference buffers, MOSFET gate drives, and cable-shield drives. The circuit shown in #SBOS6209187 uses an isolation resistor, RISO, to stabilize the output of an op amp. RISO modifies the open-loop gain of the system for increased phase margin, and results using the OPAx197-Q1 are summarized in Table 7-2. For additional information on techniques to optimize and design using this circuit, TI Precision Design TIPD128 details complete design goals, simulation, and test results.

GUID-C67D8012-6F61-43A4-830D-4A934B8558F9-low.gifFigure 7-9 Extending Capacitive Load Drive With the OPAx197-Q1
Table 7-2 OPAx197-Q1 Capacitive Load Drive Solution Using Isolation Resistor Comparison of Calculated and Measured Results
PARAMETERVALUE
Capacitive Load100 pF1000 pF0.01 µF0.1 µF1 µF
Phase Margin45°60°45°60°45°60°45°60°45°60°
RISO (Ω)473602410020516.215.824.7
Measured Overshoot (%)23.2 8.610.422.5922.18.723.18.6218.6
Calculated PM45.1°58.1°45.8°59.7°46.1°60.1°45.2°60.2°47.2°60.2°
For step-by-step design procedure, circuit schematics, bill of materials, printed circuit board (PCB) files, simulation results, and test results, see TI Precision Design TIPD128Capacitive Load Drive Solution using an Isolation Resistor.