ZHCSMO3D June   2020  – July 2021 OPA2863 , OPA4863 , OPA863

PRODUCTION DATA  

  1. 特性
  2. 应用
  3. 说明
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information: OPA863
    5. 7.5  Thermal Information: OPA2863
    6. 7.6  热性能信息:OPA4863
    7. 7.7  Electrical Characteristics: 10 V
    8. 7.8  Electrical Characteristics: 3 V
    9. 7.9  Typical Characteristics: VS = 10 V
    10. 7.10 Typical Characteristics: VS = 3 V
    11. 7.11 Typical Characteristics: VS = 3 V to 10 V
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Input Stage
      2. 8.3.2 Output Stage
        1. 8.3.2.1 Overload Power Limit
      3. 8.3.3 ESD Protection
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-Down Mode
      2. 8.4.2 Split-Supply Operation (±1.35 V to ±6.3 V)
      3. 8.4.3 Single-Supply Operation (2.7 V to 12.6 V)
  9. Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Amplifier Gain Configurations
    2. 9.2 Low-Side Current Sensing
      1. 9.2.1 Design Requirements
    3. 9.3 Transimpedance Amplifier
      1. 9.3.1 Design Requirements
      2. 9.3.2 Detailed Design Procedure
      3. 9.3.3 Application Curves
    4. 9.4 Low-Power SAR ADC Driver and Reference Buffer
    5. 9.5 Front-End Gain and Filtering
    6. 9.6 Clamp-On Ultrasonic Flow Meter
    7. 9.7 Variable Reference Generator Using MDAC
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Thermal Considerations
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 接收文档更新通知
    3. 12.3 支持资源
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 术语表
  13. 13Mechanical, Packaging, and Orderable Information

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订购信息

Detailed Design Procedure

Figure 9-5 shows how the OPAx863 devices can be used as a transimpedance amplifier (TIA) for converting a photodiode current into an output voltage. The factors which determine the minimum required gain-bandwidth product (GBW) of the amplifier are the transimpedance gain, small-signal bandwidth, and the photodiode capacitance. Increase in the values of any of these three parameters requires higher GBW. Large-area photodiodes with higher sensitivity have a relatively larger photodiode capacitance, sometimes up to 100 pF, which impacts the small-signal bandwidth, and is given below.

GUID-EB6B6A37-B4B1-46AA-916C-246717DEABE6-low.gif

The small input capacitance of OPAx863 helps to achieve a wider small-signal bandwidth, mainly limited by the photodiode capacitance. The feedback resistor RF introduces a zero in the noise gain with the total input capacitance CIN and a 40 dB/dec rate of closure. Figure 9-5 shows the feedback capacitor CF that is needed to cancel the zero due to RF, CIN with a pole in the noise gain, whose value is given below for a 65° phase margin and butterworth response.

GUID-6EF709C5-CC30-477B-B0A0-C12D49C03B23-low.gif

Equation 1 estimates a closed-loop bandwidth of 2.6 MHz. Figure 9-6 and Figure 9-7 show the closed-loop gain and phase plots from TINA-TI simulation of the TIA circuit of Figure 9-5. The 1/β gain curve has a zero from RF and CIN at 142 kHz and a pole from RF and CF cancelling the 1/β zero at 1.87 MHz, resulting in a 20-dB per decade rate-of-closure at the loop-gain crossover frequency (the frequency where AOL equals 1/β), ensuring a stable circuit. A phase margin of 65° is obtained with a closed-loop bandwidth of 2.6 MHz and a 100-kΩ transimpedance gain.