SLUAAT9 January   2024 UCC27201A , UCC27282

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Start-Up Operation
  5. 2Design Considerations
  6. 3Proper Sizing of Bootstrap and VDD Capacitors
  7. 4High Power Continuous Operation
  8. 5Design Considerations
  9. 6Summary
  10. 7References

5 Design Considerations

The ways to mitigate the possible overstress on the internal boot diode are the same as with the multiphase start up concern discussed earlier. Determine the required bootstrap capacitance to drive the high-side MOSFETs but do not oversize the capacitance value. Consider making provisions for an external boot diode with the same parameter recommendations previously discussed. Selecting a driver for these applications is important such as the LM5101(A), UCC2720x(A), UCC27211A, UCC27301A, or UCC27311A. Also, if the dead time between the low side MOSFET turn off to the high-side MOSFET turn on can be increased, this allows the boot diode current to reduce to a lower level before the switch node rises.

GUID-20240111-SS0I-BBPQ-9QFG-NFW5CLPCQ9FL-low.svgFigure 5-1 Power MOSFET Example Body Diode VF Vs IF