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

5.1.3.1 Single Slope Thermal Foldback

For a simple single-slope thermal foldback implementation, the feedback pin and the smart DAC PWM generation are used. Analog temperature sensing mechanism such as negative temperature coefficient (NTC) or an analog temperature sensor is connected to the feedback pin of the smart DAC. As the temperature rises, the voltage at the feedback pin drops due to the increase of resistivity of the NTC. The PWM duty cycle generated by the smart DAC decreases as the temperature rises. The PWM in return controls the LED driver and brightness.

The device has an integrated non-volatile memory to store configuration and autonomously generate PWM signal without the need for runtime software.

Table 5-3 Design Implementation
Hardware Block Diagram Figure 5-3 Hardware Block Diagram
Design Benefits Suggested device
  • Processor-less single-slope thermal foldback
  • PWM with duty cycle following foldback curve
End Equipment Design help