SLOS930B November   2015  – November 2019 THS4541-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      Single to Differential Gain of 2, 2-VPP Output
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics: (Vs+) – Vs– = 5 V
    6. 7.6 Electrical Characteristics: (Vs+) – Vs– = 3 V
    7. 7.7 Typical Characteristics
      1. 7.7.1 5-V Single Supply
      2. 7.7.2 3-V Single Supply
      3. 7.7.3 3-V to 5-V Supply Range
  8. 8 Parameter Measurement Information
    1. 8.1 Example Characterization Circuits
    2. 8.2 Frequency-Response Shape Factors
    3. 8.3 I/O Headroom Considerations
    4. 8.4 Output DC Error and Drift Calculations and the Effect of Resistor Imbalances
    5. 8.5 Noise Analysis
    6. 8.6 Factors Influencing Harmonic Distortion
    7. 8.7 Driving Capacitive Loads
    8. 8.8 Thermal Analysis
  9. 9 Detailed Description
    1. 9.1 Overview
      1. 9.1.1 Terminology and Application Assumptions
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Differential I/O
      2. 9.3.2 Power-Down Control Pin (PD)
        1. 9.3.2.1 Operating the Power Shutdown Feature
      3. 9.3.3 Input Overdrive Operation
    4. 9.4 Device Functional Modes
      1. 9.4.1 Operation from Single-Ended Sources to Differential Outputs
        1. 9.4.1.1 AC-Coupled Signal Path Considerations for Single-Ended Input to Differential Output Conversion
        2. 9.4.1.2 DC-Coupled Input Signal Path Considerations for Single-Ended to Differential Conversion
        3. 9.4.1.3 Resistor Design Equations for the Single-Ended to Differential Configuration of the FDA
        4. 9.4.1.4 Input Impedance for the Single-Ended to Differential FDA Configuration
      2. 9.4.2 Differential-Input to Differential-Output Operation
        1. 9.4.2.1 AC-Coupled, Differential-Input to Differential-Output Design Issues
        2. 9.4.2.2 DC-Coupled, Differential-Input to Differential-Output Design Issues
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Applications
      1. 10.2.1 Designing Attenuators
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
        3. 10.2.1.3 Application Curve
      2. 10.2.2 Interfacing to High-Performance ADCs
        1. 10.2.2.1 Design Requirements
        2. 10.2.2.2 Detailed Design Procedure
        3. 10.2.2.3 Application Curve
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Development Support
        1. 13.1.1.1 TINA Simulation Model Features
    2. 13.2 Documentation Support
      1. 13.2.1 Related Documentation
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Support Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

8.7 Driving Capacitive Loads

A very common requirement is driving the capacitive load of an ADC or some other next stage device. Directly driving a capacitive load with a closed-loop amplifier such as the THS4541-Q1 can lead to an unstable response, as shown in the step response plots into a capacitive load (see Figure 8 and Figure 26). One typical remedy for this instability is to add two small series resistors (Ro in Figure 71) at the outputs of the THS4541-Q1. Figure 6 and Figure 24 provide parametric plots of recommended Ro values versus differential capacitive load values and gain.

THS4541-Q1 ro_los375.gifFigure 71. Including Ro when Driving Capacitive Loads

Operating at higher gains requires lower Ro values to achieve a ±0.5-dB flat response for the same capacitive load. Some direct parasitic loading is acceptable with no series Ro that increases with gain setting, as illustrated in Figure 6 and Figure 24 where the Ro value is 0 Ω. Even when these plots suggest no series Ro is required, good practice is to include a place for the Ro elements in the board layout (0-Ω load initially) for later adjustment, in case the response appears unacceptable. The TINA simulation model does a good job of predicting this effect and showing the impact for different choices of capacitive load isolating resistors (Ro).