SLVAFW9 August   2024 LM51772

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Parallel or Multiphase Power Stages
    1. 2.1 Paralleling Power Stages
      1. 2.1.1 Load Balancing Requirement
    2. 2.2 Clock Generation
    3. 2.3 Interconnection of the Power Stages
  6. 3Application Implementation
    1. 3.1 Soft-start Capacitor
    2. 3.2 Compensation
    3. 3.3 Input and Output Capacitor
    4. 3.4 Usage of the Average Current Sensor
  7. 4Test Results
    1. 4.1 Load Current Balancing
    2. 4.2 Inductor Current
    3. 4.3 Thermal Images
      1. 4.3.1 Dual Phase Operation at Variable Load
      2. 4.3.2 Comparison Between Single Phase and Dual Phase Operation
  8. 5Summary
  9. 6References

2.2 Clock Generation

For an implemention of two phases, the best current balance can be obtained when running with 180 degree phase shift between the two controllers. With the R2D interface, the LM51772 can be configured to output the clock on the SYNC pin or to use the clock provided at the SYNC pin with inverted polarity. Based on that, a 2-phase operation can be easily implemented without additional external hardware. For that, the SYNC pin of both controllers needs to be connected. The first device is then configured to output the clock with EN_SYNC_OUT set to enabled, and the second device is set to use the clock on SYNC on the falling edge with SYNC_IN_FALLING set to enabled by R2D setting on CFG2 pin.

When operating the LM51772 converters with more then two phases, the clock needs to be provided from external with a phase shift between the clock for the different controllers of 360 degree or number of phases. A implementation for a clock generataion for more phases is shown in the Parallel Operation of the Buck-Boost Converters Using LM5177 Buck-Boost Controller application note.