SLASF08 December   2021 DAC43508 , DAC53508

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configurations 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
    6. 7.6  Timing Requirements: SPI
    7. 7.7  Timing Requirements: Logic
    8. 7.8  Timing Diagrams
    9. 7.9  Typical Characteristics: Static Performance
    10. 7.10 Typical Characteristics: Dynamic Performance
    11. 7.11 Typical Characteristics: General
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Digital-to-Analog Converter (DAC) Architecture
        1. 8.3.1.1 DAC Transfer Function
        2. 8.3.1.2 DAC Register Update and LDAC Functionality
        3. 8.3.1.3 CLR Functionality
        4. 8.3.1.4 Output Amplifier
      2. 8.3.2 Reference
      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 Peripheral Interface (SPI)
    6. 8.6 Register Map
      1. 8.6.1 DEVICE_CONFIG Register (address = 01h) [reset = 00FFh]
      2. 8.6.2 STATUS_TRIGGER Register (address = 02h) [reset = 0000h]
      3. 8.6.3 BRDCAST Register (address = 03h) [reset = 0000h]
      4. 8.6.4 DACn_DATA Register (address = 08h to 0Fh) [reset = 0000h]
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Programmable LED Biasing
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curve
      2. 9.2.2 Programmable Window Comparator
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.1.2 Detailed Design Procedure

The DAC is used to set the source current of a MOSFET using a unity-gain buffer, as shown in Figure 9-1. Connect the LED between the power supply and the drain of the MOSFET. This configuration allows the DAC to control or set the amount of current through the LED. The buffer following the DAC controls the gate-source voltage of the MOSFET inside the feedback loop, thus compensating this drop and corresponding drift due to temperature, current, and ageing of the MOSFET. The current set by the DAC that flows through the LED is calculated with Equation 2. To generate 0 mA to 20 mA from a 0 V to 5 V DAC output range, a 250-Ω RSET is required.

Equation 2. I S E T = V D A C R S E T

The following pseudocode is provided to help get started with the LED biasing application:

//SYNTAX: WRITE <REGISTER NAME(Hex Code)>, <DATA>
//Power-up the device and channels
WRITE DEVICE_CONFIG(0x01), 0x0000
//Program mid code (or the desired voltage) on all channels
WRITE DACA_DATA(0x08), 0x07FC //10-bit MSB aligned
WRITE DACB_DATA(0x09), 0x07FC //10-bit MSB aligned
WRITE DACC_DATA(0x0A), 0x07FC //10-bit MSB aligned
WRITE DACD_DATA(0x0B), 0x07FC //10-bit MSB aligned
WRITE DACE_DATA(0x0C), 0x07FC //10-bit MSB aligned
WRITE DACF_DATA(0x0D), 0x07FC //10-bit MSB aligned
WRITE DACG_DATA(0x0E), 0x07FC //10-bit MSB aligned
WRITE DACH_DATA(0x0F), 0x07FC //10-bit MSB aligned