SLUAAU4 June   2024 UCC28750

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Retrofit Items
  6. 3Implement SR with UCC24612-1EVM
  7. 4UCC28750 Benefits in Aux Power
  8. 5Common Issues
  9. 6Summary
  10. 7References

4 UCC28750 Benefits in Aux Power

  1. UCC28750 has dedicated fault pin to disable IC by external signal.
    In high power application, the main power stage controller uses MCU or has house keeping IC, so customer can disable Aux power when the PSU triggers the protection or the sequence requirement.
    Customer can short FLT pin to GND to disable IC easily by MCU GPIO signal.
  2. The main power stage like PFC and LLC or PSFB is very noisy and Auxpower can be modular at daughter card then closes to the main power stage components.
    UCC28750 is CCM controller, and is less sensitive than QR flyback controller, because QR flyback controller needs to sense the Auxwinding voltage to achieve the valley switching and input and output voltage detection.
  3. IC supports the power boost mode to increase the switching frequency up to two times so IC can avoid the transformer saturation during peak load, and the IC control law as Figure 4-1.
    In Auxpowr application, the main output loading is bias power for Fan, and has peak load requirement to speed up the thermal dissipation.
  4. UCC28750 is the economical flyback controller in TI.
IC Control Law Figure 4-1 IC Control Law