SLVAFK5A December   2023  – February 2024 LM5177

 

  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
  10. 7Revision History

3 Application Implementation

To demonstrate the practical implementation for the parallel operation of two buck-boost converters using LM5177 devices, an evaluation module is designed based on the block diagram shown in Figure 3-1. The designed setup has an overall power rating of 300 W and an output voltage of 16 V. Additionally, the selected peak current limit and the average current limit for each converter is 25 A and 3 A, respectively.

GUID-20230308-SS0I-2C48-XVTH-64CNKDV4RDND-low.svgFigure 3-1 Block Diagram of Two LM5177 in Parallel Operation

The value for the external components used in the power stage and with LM5177 controller can easily selected by using the LM5177 BuckBoost Quickstart Calculator Tool. Additionally, the customer can calculate these component values using the formulas shown in the application note How to Design Synchronous, Non-Inverting 4-Switch Buck-Boost Converter Using the LM5177x. These values need to be calculated for an individual power stage. Therefore, the total load current value can be divided by the number of power stages to calculate the external component values for each converter. Apart from this, some components required a special setting, as mentioned below: