SBOS778D April   2016  – April 2021 THS4551


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Companion Devices
  6. Pin Configuration and Functions
  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. 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. 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. AC-Coupled Signal Path Considerations for Single-Ended Input to Differential Output Conversions
        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. AC-Coupled, Differential-Input to Differential-Output Design Issues
        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. Design Requirements
        2. Detailed Design Procedure
        3. Application Curves
      2. 10.2.2 Differential Transimpedance Output to a High-Grade Audio PCM DAC Application
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curves
      3. 10.2.3 ADC3k Driver with a 2nd-Order RLC Interstage Filter Application
        1. Design Requirements
        2. Detailed Design Procedure
        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

Differential Transimpedance Output to a High-Grade Audio PCM DAC Application

The highest-grade audio digital-to-analog converters (DACs) are a differential current-mode output. These devices normally suggest a two-amplifier transimpedance stage to hold the DAC output voltages fixed when the amplifiers produce a differential voltage swing at the outputs. Often, the differential voltage swing is then converted to single-ended in a differencing amplifier stage to drive headphone loads (see Figure 35 in the OPA1611). The emerging high-power class D audio amplifiers often require differential inputs. Applying the THS4551 as a differential transimpedance stage offers a simple solution for very low-distortion, differential-output audio channels.

Starting with the output specifications for a very high-performance PCM1792A audio DAC, the requirements for the THS4551 interface can be extracted. The DAC is a current-sourcing device that requires its outputs to be held at ground when using a transimpedance amplifier. Using the DAC 3.3-V supply and the LM27762 low-noise, low-dropout (LDO) regulator and inverter provides a ±2.5-V supply to the THS4551. Operating the THS4551 on ±2.5-V supplies places all nodes in range for an input VCM equal to GND (and the DAC output voltages as well) and an FDA output VOCM also equal to GND.

The center current in Table 10-2 is a fixed 6.2-mA dc current coming out of the DAC outputs regardless of the DAC code. This dc common-mode current can be absorbed by the –2.5-V supply at the input pins to hold the DAC compliance voltage and FDA input pins at ground. The FDA controls the output common-mode voltage, set to ground in this case, whereas the input pin voltage (which does not move with the DAC output differential current) is controlled with a resistor to the negative supply.

Table 10-2 PCM1792A Analog Output Specification
Gain error –6 ±2 6 % of FSR
Gain mismatch, channel-to-channel –3 ±0.5 3 % of FSR
Bipolar zero (BPZ) error At BPZ –2 ±0.5 2 % of FSR
Output current Full-scale (0 dB) 7.8 mAPP
Center current At BPZ –6.2 mA

This bias is provided by the 402-Ω resistors to –2.5 V, as illustrated in Figure 10-14. This design takes the differential 7.8 mAPP from the DAC and produces a ±1.46-V swing on each output of the THS4551. This configuration gives a full-scale differential 5.85 VPP available on the ±2.5-V supply design centered at ground at both the inputs and outputs. Although the LM27762 provides a very-low noise, –2.5-V supply, using 0.1% resistors in the current sink path to the –2.5-V supply as well as the feedback resistors limits any common-mode noise on the –2.5-V supply to differential mode conversion at the FDA outputs.

GUID-7F6664BD-5D64-468A-BF7A-32CA1A3D1841-low.gif Figure 10-14 PCM1792A DAC Output Driver