SLASFL3 September   2026 DAC90802

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
    6. 5.6 Timing Requirements
    7. 5.7 Timing Diagrams
    8. 5.8 Typical Characteristics
      1. 5.8.1 Typical Characteristics: Linearity
      2. 5.8.2 Typical Characteristics: Glitch
      3. 5.8.3 Typical Characteristics: Multiplying Mode
      4. 5.8.4 Typical Characteristics: Fast-Settling Mode
      5. 5.8.5 Typical Characteristics: AWG Mode
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Digital-to-Analog Converters
        1. 6.3.1.1 Reference
        2. 6.3.1.2 Output Span
          1. 6.3.1.2.1 Gain Overrange
        3. 6.3.1.3 Output Synchronization
        4. 6.3.1.4 Thermal Sensors
      2. 6.3.2 Power-On
      3. 6.3.3 Serial Data Interface
        1. 6.3.3.1 SPI Configurations
        2. 6.3.3.2 SPI Stream Mode
        3. 6.3.3.3 SPI Daisy Chain Mode
    4. 6.4 Device Functional Modes
      1. 6.4.1 AWG Mode
      2. 6.4.2 Fast Settling Mode
      3. 6.4.3 Multiplying Mode
  8. 7 Register Maps
    1. 7.1 COMMON Registers
    2. 7.2 HS_DATA Registers
    3. 7.3 HR_DATA Registers
  9. 8 Application and Implementation
    1. 8.1 Application
    2. 8.2 Design Requirements
      1. 8.2.1 Reference Signal Chain Information
        1. 8.2.1.1 DC Reference
        2. 8.2.1.2 AC Reference
      2. 8.2.2 Optimising the Self-Heating Trim to Achieve Lowest THD Across Frequencies for High Voltage Swing
      3. 8.2.3 Digital Interface
      4. 8.2.4 Grounding Recommendations
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Recommendation
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

8.2.1.2 AC Reference

The DAC90802 architecture enables time-varying reference input (AC reference) in Multiplying Mode. Electrical parameters of importance in this mode are Multiplying Bandwidth, Multiplying THD and Multiplying Feedthrough. The device supports two reference-input configurations in this mode:

  • REFIN Configuration: REFIN configuration is recommended to achieve the best multiplying mode performance and utilizes the internal temperature-coefficient-matched resistors of DAC90802 (refer to inversion-resistor-ratio-mismatch drift from Section 5.5). This method preserves the phase of the scaled signal and requires VREFP_Sx and VREFP_Fx to be connected to a quiet analog ground, as illustrated in Figure 8-3.
DAC90802 AC Reference Signal Chain Using Internal Inversion Figure 8-3 AC Reference Signal Chain Using Internal Inversion
  • REFN Configuration (Direct Reference): In REFN configuration, VREFP_Sx and VREFP_Fx are connected to a quiet analog ground (see Figure 8-4). This method provides the most compact implementation and results in a phase inversion at the output.
DAC90802 AC Reference Signal Chain Using External Inversion Figure 8-4 AC Reference Signal Chain Using External Inversion

Depending on the application, the reference buffer must be chosen appropriately to achieve best device performance:

  • Multiplying bandwidth Requirement: The amplifier (C) must exhibit sufficient bandwidth and slew rate to accommodate the reference voltage swing.
  • THD measurements: The amplifier (C) must provide ultra-low THD at the reference voltage and frequency range of interest.

Recommended operational amplifier selections for multiplying mode are listed in Table 8-4.

Table 8-4 Operational Amplifiers Recommendation for Multiplying Mode
OP-AMP GAIN-BANDWIDTH (MHz) SLEW RATE (V/μs) THD (dB) at 100kHz DESCRIPTION
TH4631 210 550 < –90 THS4631 provides the best bandwidth across output swing to large slew rate
OPA891 180 105 < –119 OPA891 provides the best THD across frequency while supporting respectable bandwidth across output swing