SLYT837 January   2023 TPS543B22 , TPS548A28 , TPS56121

 

  1. 1 Introduction
  2. 2 Selecting and bounding the application
  3. 3 Designing the second-stage filter
  4. 4 Voltage-mode control architecture
  5. 5 D-CAP3 control architecture
  6. 6 Advanced current mode (ACM) control architecture
  7. 7 Efficiency penalty
  8. 8 Conclusion
  9. 9 References
  10. 10Related Websites

2 Selecting and bounding the application

Three different power supplies were designed and built to demonstrate the performance of each control mode under similar operating conditions. For each design, the input voltage is 12 V, the output voltage is 1 V and the output current for each device is capable of 15-A. These requirements are typical for powering a high-performance SoC that integrates sensitive analog circuitry, requiring low output voltage ripple.

To bound the filter design and performance expectations, the allowable ripple voltage is ±0.15 percent, or ±1.5 mV (3 mVpp) of the output voltage. Our comparison features three TI DC/DC converters: a 15-A D-CAP3™ buck converter (TPS548A28), a 20-A internally compensated advanced current-mode (ACM) buck converter (TPS543B22) and a 15-A voltage-mode buck converter (TPS56121). We selected output voltage, output current and operating frequencies as close as possible to one another within the converter’s capability to support similar second-stage filter components.