SLAT163 July   2024 AFE43902-Q1 , AFE439A2 , AFE53902-Q1 , AFE539A4 , AFE539F1-Q1 , AFE639D2 , DAC43204 , DAC43401 , DAC43401-Q1 , DAC43701 , DAC43701-Q1 , DAC43901-Q1 , DAC43902-Q1 , DAC53001 , DAC53002 , DAC53004 , DAC53004W , DAC53202 , DAC53204 , DAC53204-Q1 , DAC53204W , DAC53401 , DAC53401-Q1 , DAC53701-Q1 , DAC539E4W , DAC539G2-Q1 , DAC63001 , DAC63002 , DAC63004 , DAC63004W , DAC63202 , DAC63202W , DAC63204 , DAC63204-Q1 , DAC63204W

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1What is a Smart DAC?
  5. 2What is a Smart Analog Front End (AFE)?
  6. 3Smart DAC selection guide
  7. 4Smart AFE Selection Guide
  8. 5Applications
    1. 5.1 Lightning
      1. 5.1.1 Light Emitting Diode (LED) Biasing and Linear Fade-In Fade-Out
      2. 5.1.2 LED Biasing With LED Driver
      3. 5.1.3 Analog Thermal Foldback
        1. 5.1.3.1 Single Slope Thermal Foldback
        2. 5.1.3.2 Multi-Slope Thermal Foldback
      4. 5.1.4 Logarithmic Fade-In/Fade-Out
      5. 5.1.5 LED Sequencing
    2. 5.2 Control
      1. 5.2.1 Voltage Margining and Scaling With Voltage Output Smart DAC
      2. 5.2.2 Thermoelectric Cooling (TEC) Control
        1. 5.2.2.1 TEC Control Using DC/DC Driver
        2. 5.2.2.2 TEC control using h-Bridge driver
      3. 5.2.3 Analog Power Control (APC) of a Laser
      4. 5.2.4 Constant Power Control
    3. 5.3 Microcontroller Independent Fault Management and Communication
      1. 5.3.1 Programmable Comparator Using Smart DAC
      2. 5.3.2 GPI-to-PWM
      3. 5.3.3 If-Then-Else Logic
    4. 5.4 Driver
      1. 5.4.1 Lens Positioning Control for Camera Module Auto-Focus and Image Stabilization
      2. 5.4.2 Laser Drive
    5. 5.5 Miscellaneous Smart DAC Applications
      1. 5.5.1 Software-less Medical Alarm Generation
      2. 5.5.2 555 Timer

5.1.4 Logarithmic Fade-In/Fade-Out

The human eye does not perceive light linearly. To trick the eye, logarithmic fade-in and fade-out is often used to make dimming look more natural. Most of the time a combination of a micro-controller and a LED driver is used for such application. The micro-controller calculates all of the required timings and progressively increases the duty cycle of the PWM to much logarithmic dimming requirement.

With DAC43902 however, there is no need for software to implement such operation. The smart DAC using the internal state machine progressively increases (if fading-in) or decreases (if fading out) the duty cycle of the PWM signal supplied to LED driver. This increase/decrease of the PWM duty cycle produces logarithmic animation to the LEDs.

The dimming timing, PWM frequency, and duty cycle can be customized through the internal registers and stored into the device non-volatile memory to remove the need for run-time software.

Table 5-5 Design Implementation
Hardware Block DiagramFigure 5-5 Hardware Block Diagram
Design BenefitsSuggested device
  • Processor-less logarithmic dimming
  • Logarithmic increase of PWM duty cycle
  • PWM output up to 48.8kHz
  • Fully customizable timing
  • NVM to store all configurations to remove the need for run-time software
End EquipmentDesign help