JAJSKH1C March   2022  – October 2023 LMH34400

PRODUCTION DATA  

  1.   1
  2. 特長
  3. アプリケーション
  4. 概要
  5. Pin Configuration and Functions
  6. Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Electrical Characteristics: Logic Threshold and Switching Characteristics
    7. 5.7 Typical Characteristics
  7. Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Clamping and Input Protection
      2. 6.3.2 ESD Protection
      3. 6.3.3 Single-Ended Output Stage
    4. 6.4 Device Functional Modes
      1. 6.4.1 Ambient Light Cancellation Mode
      2. 6.4.2 Power-Down Mode (Multiplexer Mode)
  8. Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 LMH34400 Test Circuit
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
        3. 7.2.1.3 Application Curves
      2. 7.2.2 LMH34400 Signal Chain With Comparator
        1. 7.2.2.1 Design Requirements
        2. 7.2.2.2 Detailed Design Procedure
        3. 7.2.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 サポート・リソース
    5. 8.5 Trademarks
    6. 8.6 静電気放電に関する注意事項
    7. 8.7 用語集
  10. Revision History
  11. 10Mechanical, 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

Ambient Light Cancellation Mode

The LMH34400 has an integrated DC cancellation loop that can used to cancel any voltage offsets resulting from ambient light. The DC cancellation loop is enabled by setting IDC_EN low. Incident ambient light on a photodiode produces a DC current resulting in an offset voltage at the output of the TIA stage. If the photodiode produces a DC output current resulting from ambient light, then the output of the level-shift buffer stage is offset from the reference voltage VREF. The ALC loop detects this offset and produces an opposing DC current to compensate for the differential offset voltage at its input. The loop has a high-pass cutoff frequency of 400 kHz. The ambient light cancellation loop is disabled when the amplifier is placed in low-power mode.

The shot noise current introduced by the DC cancellation loop increases the overall amplifier noise. So, if the ambient light level is negligible, then disable the loop to improve SNR. The cancellation loop helps save PCB space and system costs by eliminating the need for external AC coupling passive components. Additionally, the extra trace inductance and PCB capacitance introduced by using external AC coupling components degrades the LMH34400 dynamic performance.