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[FAQ] PMP21251: How do UCC28056 and UCC256304 help maintain high efficiency across all load operations in low cost, high efficiency, offline AC/DC converters?

Part Number: PMP21251
Other Parts Discussed in Thread: UCC28056, UCC256304

How do UCC28056 and UCC256304 help maintain high efficiency across all load operations in low cost, high efficiency, offline AC/DC converters?

  • PMP21251 is a TI Power Reference Design solution that helps develop high efficiency and cost effective power solutions for delivering isolated 12V/170W for offline AC/DC industrial and personal electronic applications.

    UCC28056 is a high performance CRM/DCM PFC controller that operates in Transition mode (TM) at full load and seamlessly transitions into Discontinuous Conduction mode (DCM) at light loads. Additionally, this device incorporates burst mode operation to further improve light load performance, enabling systems to meet challenging energy standards while eliminating the need to switch off the PFC.

    In this application, UCC256304 LLC resonant controller provides an isolated 12V/10.8A output (continuous, 14.4A peak) after the PFC AC/DC conversion. With advanced burst mode, this PFC + LLC system can achieve 94% peak efficiency and 89 mW no-load standby power without turning off the PFC at 230 VAC input, surpassing all the stringent energy standards. Many systems previously used auxiliary Flybacks and had to switch off the PFC at standby to meet these energy standards. UCC256304 plus UCC28056 can achieve 89mW standby power with PFC always on, and this eliminates the need for the auxiliary Flyback, thus saving cost greatly.

    Each of these features is demonstrated in the PMP21251 Reference Design, which can be used to power numerous industrial and personal electronic AC/DC applications, such as all-in-one PC, LCD TV, and adapters.

    To learn more about the performance of this reference design under typical and stress test conditions, refer to section 2 "Testing and Results" of the User Guide for PMP21251.

    You can also download the design files (BOM, Schematic, Gerber) for this reference design from the PMP21251 folder.