SLVAE69 July   2019 TPS568215 , TPS56C215

 

  1.   Expand Buck Converter Minimum Input Voltage with External VCC Bias
    1.     Trademarks
    2. 1 TPS56C215 Introduction
    3. 2 12 V / 5 V O-ring supply for DDR application
    4. 3 Schematic and Bench Results
      1. 3.1 Efficiency Comparison
      2. 3.2 Bench Waveforms
    5. 4 Conclusion
    6. 5 References

4 Conclusion

5 V and 12 V ORing supply rails are common in server applications. Using the system 5 V rail as an external VCC bias supply could extend the minimum input voltage while also improving 12 V rail efficiency. The detailed schematic based on TPS56C215, along with bench testing, both verify the theory.