SNVU822 May   2022

 

  1.   Trademarks
  2. 1Introduction
  3. 2Warnings and Cautions
  4. 3Description
    1. 3.1 Typical Applications
    2. 3.2 Features
    3. 3.3 Connector and Test Point Description
    4. 3.4 Electrical Performance Specifications
  5. 4Test Setup
    1. 4.1 Input Supplies and LED Load Connections
    2. 4.2 Analog Duty Cycle Control Using APWM
    3. 4.3 Analog Dimming Using IADJ
    4. 4.4 PWM Dimming Using nExt_PWM Test Points
    5. 4.5 Switching Frequency Set Point Using RON
  6. 5Performance Data and Typical Characteristic Curves
    1. 5.1 Efficiency
    2. 5.2 Analog Dimming
    3. 5.3 PWM Dimming
    4. 5.4 PWM Dimming Waveforms
  7. 6Schematic
  8. 7TPS92643EVM-204 PCB Layout
  9. 8Bill of Materials

4.3 Analog Dimming Using IADJ

Analog Dimming is controlled by IADJ (TP8) test point or by using the resistor divider attached to VCC. The voltage on the IADJ pin sets the regulated LED current by the following equation.

Equation 1.
Figure 4-4 IADJ Using External Supply

There is a placeholder for resistor divider and RFB2 (R7) and RFB1 (R12) has to be calculated for the desired ILED. See Figure 4-5 and Equation 2 for the circuit diagram and equation. The voltage on IADJ (TP8) controls the output current. See Figure 4-6.

Equation 2.
Figure 4-5 Setting IADJ Using On-Board Resistor Divider
Figure 4-6 IADJ Using Resistor Divider