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

3.1 Efficiency Comparison

With external VREG5 supplied, the internal LDO is disabled. The analog circuitry and driver power supply will come from the external VREG5 supply. While monitoring 12 V normal input rail efficiency, it could be observed that the external VREG5 supply efficiency is slightly higher than internal VREG5 supply. The comparison curve is shown in Figure 5.

Figure5-TPS56C215-Efficiency.gifFigure 5. Efficiency Comparison Between Internal and External VREG5 Power Supply