SDAA210 November   2025 LM5125-Q1 , LM51251A-Q1 , LM5125A-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Application Implementation
  6. 3Design Considerations
  7. 4Test Results
    1. 4.1 Efficiency Measurements
    2. 4.2 Device Features
      1. 4.2.1 Soft-Start (SS)
      2. 4.2.2 Over-Voltage Protection (OVP)
      3. 4.2.3 Second phase enable (EN2)
      4. 4.2.4 Bypass mode
    3. 4.3 Load Transient
    4. 4.4 Line Transient
    5. 4.5 Temperature Measurements
    6. 4.6 Bode Plot
  8. 5Summary
  9. 6References

5 Summary

As shown in the above images and scope plots, the LM5125x works properly in asynchronous mode. Nevertheless, some drawbacks have to be considered: even if overall BOM will be lower by replacing the high-side FET with a diode and removing the bootstrap capacitor, but the converter have a 2 to 3% lower efficiency (because of higher conduction losses of the diodes with respect to a transistors) and will therefore have higher heat dissipation at the same output voltage. With that being said, in order to make the LM5125x working in asynchronous mode, the evaluation module can be reworked to build the 5V step required between HBx and SWx pins to correctly operate the high-side driver (even if the HO1/HO2 pins are left floating).