TIDUEW9 April   2020

 

  1.    Description
  2.    Resources
  3.    Features
  4.    Applications
  5.    Design Images
  6. 1System Overview
    1. 1.1 Key System Specifications
    2. 1.2 Block Diagram
    3. 1.3 Top Side Pump
    4. 1.4 LED Driver Input Signals
    5. 1.5 LED Driver SDIM/UDIM Settings
    6. 1.6 TPS92641 Board Description
    7. 1.7 Setting the LED Current and Analog Dimming
    8. 1.8 PWM Dimming
  7. 2LED Driver Key Parameters
    1. 2.1 Enable and Disable Delay
    2. 2.2 Rise and Fall Time
    3. 2.3 Ripple
    4. 2.4 Performance Parameters
    5. 2.5 LED Load Capacitor for Rise/Fall Time
    6. 2.6 LED Load Capacitor And Audible Noise
      1. 2.6.1 Layout Considerations
      2. 2.6.2 Electrolytic capacitor considerations
      3. 2.6.3 Standoff Capacitors
    7. 2.7 LED Driver Calculator Tool
  8. 3Layout
  9. 4Related Documentation
    1. 4.1 Trademarks
    2. 4.2 Third-Party Products Disclaimer

1.7 Setting the LED Current and Analog Dimming

Average LED current regulation is set by using a sense resistor in-series with the LEDs. The internal error amplifier regulates the voltage across the sense resistor (VCS) to the IADJ voltage divided by 10. IADJ can be set to any value up to 2.54 V by connecting it to VREF through a resistor divider for static output current settings. IADJ can also be used to change the regulation point if connected to a controlled voltage source or potentiometer to provide analog dimming. The ILED setting is based on the equations in Equation 1.

Equation 1. TIDA-080008 tida080008-equation-1.gif