SBAS794E november   2018  – august 2023 DAC60501 , DAC70501 , DAC80501

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Device Comparison Table
  7. 6 Pin Configuration and Functions
  8. 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
    6. 7.6  Timing Requirements: SPI Mode
    7. 7.7  Timing Requirements: I2C Standard Mode
    8. 7.8  Timing Requirements: I2C Fast Mode
    9. 7.9  Timing Requirements: I2C Fast-Mode Plus
    10. 7.10 Timing Diagrams
    11. 7.11 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 DAC Architecture
        1. 8.3.1.1 DAC Transfer Function
        2. 8.3.1.2 DAC Register Structure
        3. 8.3.1.3 Output Amplifier
      2. 8.3.2 Internal Reference
        1. 8.3.2.1 Solder Heat Reflow
      3. 8.3.3 Power-On-Reset (POR)
      4. 8.3.4 Software Reset
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-Down Mode
    5. 8.5 Programming
      1. 8.5.1 Serial Interface
        1. 8.5.1.1 SPI Mode
          1. 8.5.1.1.1 SYNC Interrupt
        2. 8.5.1.2 I2C Mode
          1. 8.5.1.2.1 F/S Mode Protocol
          2. 8.5.1.2.2 I2C Update Sequence
            1. 8.5.1.2.2.1 Address Byte
            2. 8.5.1.2.2.2 Command Byte
            3. 8.5.1.2.2.3 Data Byte (MSDB and LSDB)
          3. 8.5.1.2.3 I2C Read Sequence
    6. 8.6 Register Map
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Charge Injection
        2. 9.2.2.2 Voltage Droop
        3. 9.2.2.3 Output Offset Error
        4. 9.2.2.4 Switch Selection
        5. 9.2.2.5 Amplifier Selection
        6. 9.2.2.6 Hold Capacitor Selection
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2.3 Output Offset Error

The output offset error of a sample-and-hold channel is the cumulative error contributed by the DAC offset error, amplifier offset error, and sample-and-hold pedestal error due to charge injection. The amplifier offset error can be made negligible by choosing a low-offset amplifier, such as the OPA4317. The OPA4317 has a maximum offset error of 0.1 mV. The DAC80501 has a maximum offset error of ±1.5 mV. Thus, to achieve a total offset error less than ±3 mV, limit the offset error contributed by the sample-and-hold circuit to ±1.5 mV.

Considering the bias current of 300 pA in the OPA4317, and a typical switch leakage current of 1 nA, a 2‑nF hold capacitor results in a droop rate of 0.65 V/s. When the sample-and-hold circuit refreshes at a rate of more than 100 µs, the voltage droop is 65 µV. This small offset error can be ignored for the simplicity of calculation. Thus, the only contributor to the sample-and-hold offset error is the pedestal error. For a charge injection of 3 pC and a pedestal error of 1.5 mV, the value of the hold capacitor is calculated as 2 nF, according to Equation 2. A capacitive load of 2 nF can be handled by the DAC80501. The switch-on resistance and optional series resistance RS further helps in the stability of the DAC output amplifier. RS can be omitted for better settling time.