JAJSI19D October   2019  – January 2023 LMH32401

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
    5. 6.5 Electrical Characteristics: Gain = 2 kΩ
    6. 6.6 Electrical Characteristics: Gain = 20 kΩ
    7. 6.7 Electrical Characteristics: Both Gains
    8. 6.8 Electrical Characteristics: Logic Threshold and Switching Characteristics
    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 Switched Gain Transimpedance Amplifier
      2. 7.3.2 Clamping and Input Protection
      3. 7.3.3 ESD Protection
      4. 7.3.4 Differential Output Stage
    4. 7.4 Device Functional Modes
      1. 7.4.1 Ambient Light Cancellation (ALC) Mode
      2. 7.4.2 Power-Down Mode (Multiplexer Mode)
  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
      3. 8.2.3 Application Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
    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

デバイスごとのパッケージ図は、PDF版データシートをご参照ください。

メカニカル・データ(パッケージ|ピン)
  • RGT|16
  • Y|0
サーマルパッド・メカニカル・データ
発注情報

Clamping and Input Protection

The LMH32401 device is designed to work with photodiode (PD) configurations that can source or sink current; however, the LMH32401 is optimized for a sinking current configuration. It is assumed that the LMH32401 device is being used with a PD that is configured with its cathode tied to the amplifier input and the anode tied to a negative supply voltage, unless stated otherwise.

The LMH32401 features two internal clamps, a fast recovery clamp and a soft clamp. The fast recovery clamp is the active clamp when the photodiode is sinking a photocurrent. The soft clamp is the active clamp when the photodiode is sourcing a photocurrent. Stray reflections from nearby objects with high reflectivity can produce large output current pulses from the PD. The linear input range of the LMH32401 device is approximately 65 µA in the high-gain configuration and 650 µA in the low-gain configuration (PD sinking the photocurrent).

Input currents in excess of the linear current range cause the internal nodes of the amplifier to saturate, which increases the amplifier recovery time. The end result is a broadening of the output pulse leading to blind zones in the system response. To protect against this condition, the LMH32401 features an integrated clamp that absorbs and diverts the excess current to the positive supply (VDD1) when the amplifier detects its nodes entering a saturated condition. The integrated clamp minimizes the pulse extension to less than a few ns for input pulses up to 100 mA. The power-supply pins (VDD1 and VDD2) must each have their own bypass capacitors to prevent large input pulses from affecting the differential output stage. When the amplifier is in low-power mode, the clamp circuitry is still active, thereby protecting the TIA input.