SLVUBB4B November   2017  – February 2023

 

  1.   Abstract
  2.   Trademarks
  3. 1 Topologies Window
  4. 2 FET Losses Calculator
  5. 3 Load Step Calculator
  6. 4 Capacitor Current Sharing Calculator
  7. 5 AC/DC Bulk Capacitor Calculator
  8. 6 RCD-Snubber Calculator for Flyback Converters
  9. 7 RC-Snubber Calculator
  10. 8 Output Voltage Resistor Divider
  11. 9 Dynamic Analog Output Voltage Scaling
  12. 10Dynamic Digital Output Voltage Scaling
  13. 11Unit Converter
  14. 12Loop Calculator
    1. 12.1 Inputs
    2. 12.2 Transfer Functions
      1. 12.2.1  Output Impedance Transfer Function
      2. 12.2.2  Transfer Function VMC Buck Power Stage
      3. 12.2.3  Transfer Function CMC Buck Power Stage
      4. 12.2.4  Transfer Function CMC Boost Power Stage
      5. 12.2.5  Transfer Function CMC Inverting Buck-Boost Power Stage
      6. 12.2.6  Transfer Function CMC Forward Power Stage
      7. 12.2.7  Transfer Function CMC Flyback Power Stage
      8. 12.2.8  Transfer Function Closed Loop
        1. 12.2.8.1 Transfer Function Type II Compensation Network
        2. 12.2.8.2 Transfer Function Type II Transconductance Compensation Network
        3. 12.2.8.3 Transfer Function Type III Compensation Network
      9. 12.2.9  Transfer Function Isolated Type II Compensation Network With a Zener Clamp
      10. 12.2.10 Transfer Function Isolated Type II Compensation Network Without a Zener Clamp
  15. 13Filter Designer
    1. 13.1 Impedances
    2. 13.2 Transfer Functions
    3. 13.3 Filter Output Impedance
    4. 13.4 Damping Factor
  16. 14Additional Information
  17. 15Revision History

9 Dynamic Analog Output Voltage Scaling

If the output voltage of a power supply must be adjustable, add a third resistor to the feedback resistor divider and apply an analog voltage to this resistor (for example, with the DAC of a microcontroller). The analog signal can also be provided by smoothing a PWM signal with a low-pass filter. After entering the minimum output voltage, maximum output voltage, reference voltage, maximum adjusting voltage signal, and the desired value for the top feedback resistor, Power Stage Designer calculates the required bottom feedback resistance and the adjusting voltage signal series resistance, as well as the minimum bias current going through the top feedback resistor.

#T5147377-30 shows the Dynamic Output Voltage Scaling Calculator window.

GUID-C7D85D80-752F-45EA-AA31-560C46F91096-low.pngFigure 9-1 Dynamic Output Voltage Scaling Calculator Window
I R 1 , m i n = V o u t , m i n - V r e f R 1
R 3 = R 1 × V a d j , m a x V o u t , m a x - V r e f - R 1 × I R 1 , m i n
Equation 26. R 2 = R 1 × R 3 × V r e f R 3 × V o u t , m a x - R 3 × V r e f - R 1 × V r e f