SLUA987C October   2019  – February 2023 UCC27531-Q1 , UCC28700-Q1 , UCC28730-Q1 , UCC28740-Q1 , UCC28C40-Q1 , UCC28C41-Q1 , UCC28C42-Q1 , UCC28C43-Q1 , UCC28C44-Q1 , UCC28C45-Q1


  1.   Abstract
  2.   Trademarks
  3. 1Introduction
  4. 2Selecting Devices
  5. 3Start-Up Circuitry
  6. 4Noise Coupling
  7. 5Safety
  8. 6Summary
  9. 7Related Documentation
  10. 8Revision History


The distance between the high-voltage area at the primary side, and low-voltage area at the secondary side, must have enough clearance to comply with standards such as IEC 60664-1. The ground of the low-voltage side can be connected to a 12-V battery or vehicle chassis, which a user can come in contact with. Therefore, a transformer with reinforced isolation and AEC-Q200 Grade 1 compliance is recommended for this application.

The primary-side regulated flyback solutions, UCC28700-Q1 and UCC28730-Q1, do not require an optocoupler for feedback. This eliminates a component crossing the isolation barrier, and provides a more cost-effective solution. UCC28C56H-Q1 can be configured as a primary-side regulated solution by using an auxiliary winding for feedback.

Not all system can be actively cooled through water or fans. So hot points like the transformer windings, power transistor, or rectification diodes can be managed using thermal vias, internal layers, and heatsinks.