SBOSA51 December   2020 THS4567

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: Differential TIA Mode, ICM loop enabled
    6. 6.6 Electrical Characteristics: FDA operation, ICM loop disabled
    7. 6.7 Typical Characteristics: (VS+) – (VS–) = 5 V
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Main Amplifier
      2. 7.3.2 Output Common-Mode Control
      3. 7.3.3 Input Common-Mode Control
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Differential Transimpedance Amplifier Mode
      3. 7.4.3 Fully Differential Amplifier (FDA) Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Noise Analysis
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure (THS4567 in TIA Mode)
        1. 8.2.2.1 OPA Mode Configuration
      3. 8.2.3 Application Curves
    3. 8.3 Differential TIA with 0-V Biased Photodiode
    4. 8.4 Differential AC Coupled TIA
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Board Layout Recommendations
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.2.2.1 OPA Mode Configuration

The OPA mode configuration is shown in Figure 8-3. This configuration results in a reverse bias of (5.25 V - 5 V = 0.25 V) across the PD thereby greatly increasing the PD capacitance compared to the TIA mode.

In the OPA mode there is no input common-mode current cancellation so the maximum value of feedback resistance (RF, RF') is the ratio of the maximum single-ended output swing and the maximum single-ended input current as shown in Equation 5.

Equation 5. Maximum TIA gain = (5 V/15 µA) = 333.33 kΩ

The total differential swing is 333.33 kΩ × 10 µAPP = 3.33 V. To maximize the ADC gain range a subsequent amplifier gain stage is needed. The second gain stage which is typically implemented with a standard FDA like the THS4561 will also adjust the output common-mode to match the ADCs input common-mode compliance range.

As the level of ambient light increases relative to the differential signal from the PD, the maximum gain configuration in the OPA mode will decrease while it stays constant for the THS4567 TIA mode.