SBOS778D April   2016  – April 2021 THS4551

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Companion Devices
  6. 6 Pin Configuration and 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: (VS+) – (VS–) = 5 V
    8. 7.8 Typical Characteristics: (VS+) – (VS–) = 3 V
    9. 7.9 Typical Characteristics: 3-V to 5-V Supply Range
  8. 8 Parameter Measurement Information
    1. 8.1 Example Characterization Circuits
    2. 8.2 Output Interface Circuit for DC-Coupled Differential Testing
    3. 8.3 Output Common-Mode Measurements
    4. 8.4 Differential Amplifier Noise Measurements
    5. 8.5 Balanced Split-Supply Versus Single-Supply Characterization
    6. 8.6 Simulated Characterization Curves
    7. 8.7 Terminology and Application Assumptions
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Differential Open-Loop Gain and Output Impedance
      2. 9.3.2 Setting Resistor Values Versus Gain
      3. 9.3.3 I/O Headroom Considerations
      4. 9.3.4 Output DC Error and Drift Calculations and the Effect of Resistor Imbalances
    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 Conversions
        2. 9.4.1.2 DC-Coupled Input Signal Path Considerations for Single-Ended to Differential Conversions
      2. 9.4.2 Operation from a Differential Input to a Differential Output
        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
      3. 9.4.3 Input Overdrive Performance
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Noise Analysis
      2. 10.1.2 Factors Influencing Harmonic Distortion
      3. 10.1.3 Driving Capacitive Loads
      4. 10.1.4 Interfacing to High-Performance Precision ADCs
      5. 10.1.5 Operating the Power Shutdown Feature
      6. 10.1.6 Designing Attenuators
      7. 10.1.7 The Effect of Adding a Feedback Capacitor
    2. 10.2 Typical Applications
      1. 10.2.1 An MFB Filter Driving an ADC Application
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
        3. 10.2.1.3 Application Curves
      2. 10.2.2 Differential Transimpedance Output to a High-Grade Audio PCM DAC Application
        1. 10.2.2.1 Design Requirements
        2. 10.2.2.2 Detailed Design Procedure
        3. 10.2.2.3 Application Curves
      3. 10.2.3 ADC3k Driver with a 2nd-Order RLC Interstage Filter Application
        1. 10.2.3.1 Design Requirements
        2. 10.2.3.2 Detailed Design Procedure
        3. 10.2.3.3 Application Curve
  11. 11Power Supply Recommendations
    1. 11.1 Thermal Analysis
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 Board Layout Recommendations
    2. 12.2 Layout Example
    3. 12.3 EVM Board
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 TINA-TI 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

10.1.4 Interfacing to High-Performance Precision ADCs

The THS4551 provides a simple interface to a wide variety of precision SAR and delta-sigma (ΔΣ) ADCs. To deliver the exceptional distortion at the output pins, considerably wider bandwidth than what is typically required in the signal path to the ADC inputs is provided by the THS4551. This wide amplifier bandwidth provides the low broadband, closed-loop output impedance to supply the sampling glitches and to recover quickly for the best SFDR. A particularly challenging task is to drive the high-frequency modulator sample rates for a precision ΔΣ converter where the modulator frequency can be far higher than the final output data rate. Figure 10-2 shows a tested example circuit using the THS4551 in a 500-kHz, active multiple feedback (MFB) filter driving the 24-bit ADS127L01. This filter is designed for FO = 500 kHz and Q = 0.63 to give a linear phase response with the –3-dB frequency at 443 kHz. This example circuit is available as a TINA-TI™ simulation file.

GUID-385553E7-1054-47E7-8AC9-9762D28369BB-low.gifFigure 10-2 500-kHz Low-Pass Active Filter

This 3-V supply example provides a low-power interface to the very low-power ADC. This circuit is available on the ADS127L01EVM board.

The 5-Ω resistors inside the loop at the output pins and the 1-nF differential capacitor across the FDA input pins are not part of the filter design. These elements function to improve the loop-phase margin with minimal interaction with the active filter operation To observe the loop gain and phase margin, use the SBOC461 TINA-TI™ simulation file. Tested performance with the ADS127L01 at a 4-kHz input shows the exceptional THD and SNR of –114 dBc and 106 dB, respectively. Figure 10-3 uses the ADS127L01 at a modulator frequency of 16 MHz.

GUID-66FEC652-7CEB-4AE8-927A-4D7E855BAF54-low.gifFigure 10-3 4-kHz FFT Test for the Gain of 1 V/V Interface in Figure 10-2