SBOSA39A April   2025  – October 2025 THS3470

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics ±VS = ±30V
    6. 5.6 Electrical Characteristics ±VS = ±20V
    7. 5.7 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Output Current Limit
      2. 6.3.2 Output Current Enable
      3. 6.3.3 Over Temperature Flag
      4. 6.3.4 Output Current Flags
      5. 6.3.5 Output Current Monitoring
      6. 6.3.6 Die Temperature Monitoring
      7. 6.3.7 External Compensation
    4. 6.4 Device Functional Modes
      1. 6.4.1 Power Modes
      2. 6.4.2 Choosing a Feedback Resistor
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 High-Voltage, High-Precision, Composite Amplifier
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
        3. 7.2.1.3 Application Curves
      2. 7.2.2 120V Bootstrap Amplifier
        1. 7.2.2.1 Design Requirements
        2. 7.2.2.2 Detailed Design Procedure
        3. 7.2.2.3 Application Performance Plots
    3. 7.3 Short Circuit Protection
    4. 7.4 Power Supply Recommendations
    5. 7.5 Layout
      1. 7.5.1 Thermal Considerations
        1. 7.5.1.1 Top-Side Cooling Benefits
        2. 7.5.1.2 THS3470 Safe Operating Area
      2. 7.5.2 Layout Guidelines
      3. 7.5.3 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Documentation Support
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 TAPE AND REEL INFORMATION

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • REB|42
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.2.1.2 Detailed Design Procedure

The THS3470 is designed for use as a high-slew-rate (3000V/μs), high-output-current (±1.35A), and high-output-swing (50VPP) device. These performance features make the THS3470 a great candidate for the output amplifier of a high-voltage and precision composite amplifier. In addition to the performance specifications, the THS3470 has a host of diagnostic functions, such as current and temperature flags and current and temperature monitors, that allow system designers to tightly control and monitor the full system design better than discrete transistors.

The OPA863A is a high-precision, high-bandwidth amplifier that is an excellent choice to perform as an input amplifier in a composite loop. The low offset (95μV) and offset drift (1.2μV/°C) of the OPA863A allows the composite amplifier to settle to the target output-referred error and minimize heating effects from the THS3470 power dissipation into the PCB. Additionally, the high bandwidth of the OP863A (50MHz) allows the small-signal ripple to be minimized for a fast-settling response after the large transient step.

The total composite amplifier loop gain is defined by the external feedback network formed by R1 and R2, which is configured in a gain of 10. This value is chosen to optimize for a 5V DAC, but can be easily adjusted to a gain of 20 by changing R1 to 100Ω to support a 3.3V DAC. The THS3470 amplifier, configured in a local gain of 10 by the feedback network formed by R3 and R4, does not have a large impact on the signal source to DUT output gain. Instead, this amplifier divides the output voltage seen by the OPA863A by a factor of 10. This gain works well for the OPA863A with a 5V supply because the maximum output range of the OPA863A is only 5V. The gain of the THS3470 also gains up the slew rate of the OPA863A to 1000V/μs from the inherent 100V/μs slew rate of the device. Faster slew rates are possible by increasing the THS3470 gain, but an increased slew-rate does not always equate to faster settling time in this configuration.

Figure 7-2 shows an example PCB that was built to characterize the performance of the composite loop design. Without the composite loop, Figure 7-3 shows the output referred error that occurs after RS, on the "DUT side" of the 5Ω isolation resistor, with a normal THS3470EVM. Figure 7-4, by contrast, shows the output referred error on the "DUT side" of the isolation resistor to be less than 10mV for the composite design. For a full 40VPP step, Figure 7-5 shows the transient behavior of the THS3470EVM and composite amplifiers side by side. While the precision of the composite amplifier has been drastically improved, the composite design does come at the expense of worse settling and slew rate performance compared to the default THS3470EVM.

THS3470 THS3470 Composite Amplifier PCB Figure 7-2 THS3470 Composite Amplifier PCB