UCC28780 Adaptive zero voltage switching active-clamp flyback controller | TI.com

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Adaptive zero voltage switching active-clamp flyback controller



UCC28780 is a high-frequency active-clamp flyback controller that enables high-density AC-to-DC power supplies that comply with stringent global efficiency standards such as DoE Level VI and EU CoC V5 Tier-2. User programmable advanced control law features allow performance to be optimized for both Silicon (Si) and Gallium Nitride (GaN) power FETs. Direct operation with switching devices that combine driver and GaN FETs is further enhanced with logic-level gate signals and enable outputs.

Zero voltage switching (ZVS) is achieved over a wide operating range with advanced auto-tuning techniques, adaptive dead-time optimization, and variable switching frequency control law. Using adaptive multimode control that changes the operation based on input and output conditions, UCC28780 enables high efficiency while mitigating audible noise. With a variable switching frequency of up to 1 MHz and accurate programmable over-power protection, which provides consistent power for thermal design across wide line range, the size of passive components can be further reduced and enable high power density.

UCC28780 works with VDS-sensing synchronous rectifier controllers, such as UCC24612, to achieve higher conversion efficiency and very compact designs.


  • Full and Partial Zero Voltage Switching (ZVS) of Primary FET with Adaptive Control
  • Programmable Timing for External Si or GaN FETs
  • High Switching Frequency up to 1 MHz
  • Programmable Adaptive Burst Control and Standby Mode for Light-Load Efficiency with Low Output Ripple and Audible Noise Mitigation
  • Brownout Detection without Direct Line Sensing
  • Accurate Programmable Over-Power Protection (OPP) to Support Peak Power Mode
  • Fault Protections: Over-Temperature, Output Over-Voltage, Output Short-Circuit, Over-Current, and Pin Fault
  • Direct Interface with Optocoupler Based Feedback Allows for Dynamically Scalable Output Voltage
  • Internal Soft Start
  • NTC Thermistor Interface with External Enable

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Part number Order Control method Duty cycle (Max) (%) Frequency (Max) (kHz) UVLO thresholds on/off (V) Features Operating temperature range (C) Package Group Rating Package size: mm2:W x L (PKG)
UCC28780 Order now Secondary-side regulation     99     1000     17.5/10     SSR
Zero Voltage Switching    
-40 to 125     SOIC | 16
WQFN | 16    
Catalog     16SOIC: 59 mm2: 6 x 9.9 (SOIC | 16)
16WQFN: 9 mm2: 3 x 3 (WQFN | 16)    
LM5023 Order now Secondary-side regulation     100     130     12.8/7.5     Quasi-Resonant
Green Mode
Light Load Efficiency    
-40 to 125     VSSOP | 8     Catalog     8VSSOP: 15 mm2: 4.9 x 3 (VSSOP | 8)    
UCC28600 Order now Secondary-side regulation     99     130     10.3/9.3     SSR
Error Amplifier
Green Mode
Light Load Efficiency    
-40 to 105     SOIC | 8     Catalog     8SOIC: 19 mm2: 3.91 x 4.9 (SOIC | 8)    
UCC28610 Order now Secondary-side regulation     100     130     10.2/8     SSR
HV Start-up
-40 to 125     PDIP | 8
SOIC | 8    
Catalog     8PDIP: 93 mm2: 9.43 x 9.81 (PDIP | 8)
8SOIC: 19 mm2: 3.91 x 4.9 (SOIC | 8)    
UCC28704 Order now Primary-side regulation     99     85     21/7.7     PSR
-40 to 125     SOT-23 | 6     Catalog     6SOT-23: 5 mm2: 1.6 x 2.9 (SOT-23 | 6)    
UCC28740 Order now Secondary-side regulation     99     100     21/7.75     SSR
HV Start-up
-40 to 125     SOIC | 7     Catalog     7SOIC: 29 mm2: 6 x 4.9 (SOIC | 7)