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UCC28950
SLUSA16D – MARCH 2010 – REVISED NOVEMBER 2016
UCC28950 Green Phase-Shifted Full-Bridge Controller With Synchronous Rectification
1 Features
•1 Enhanced Wide Range Resonant Zero Voltage Switching (ZVS) Capability
• Direct Synchronous Rectifier (SR) Control • Light-Load Efficiency Management Including
– Burst Mode Operation – Discontinuous Conduction Mode (DCM),
Dynamic SR On and Off Control with Programmable Threshold – Programmable Adaptive Delay • Average or Peak Current Mode Control With Programmable Slope Compensation and Voltage Mode Control • Naturally Handles Pre-Biased Start Up With DCM Mode • Closed Loop Soft Start and Enable Function • Programmable Switching Frequency up to 1 MHz with Bi-Directional Synchronization • (±3%) Cycle-by-Cycle Current Limit Protection With Hiccup Mode Support • 150-µA Start-Up Current • VDD Undervoltage Lockout • Wide Temperature Range –40°C to +125°C
2 Applications
• Phase-Shifted Full-Bridge Converters • Datacom, Telecom, and Wireless Base-Station
Power • Server, Power Supplies • Industrial Power Systems • High-Density Power Architectures • Solar Inverters, and Electric Vehicles
3 Description
The UCC28950 enhanced phase-shifted controller builds upon Texas Instrument’s industry standard UCx895 phase-shifted controller family with enhancements that offer best in class efficiency in today’s high performance power systems. The UCC28950 implements advanced control of the fullbridge along with active control of the synchronous rectifier output stage.
The primary-side signals allow programmable delays to ensure ZVS operation over wide-load current and input voltage range, while the load current naturally tunes the secondary-side synchronous rectifiers switching delays, maximizing overall system efficiency.
The UCC28950 also offers multiple light-load management features including burst mode and dynamic SR on/off control when transitioning in and out of Discontinuous Current Mode (DCM) operation, ensuring ZVS operation is extended down to much lighter loads.
In addition, the UCC28950 includes support for current or voltage mode control. Programmable switching frequency up to 1 MHz and a wide set of protection features including cycle-by-cycle current limit, UVLO and thermal shutdown. A 90-degree phase-shifted interleaved synchronized operation can be easily arranged between two converters.
The UCC28950 is available in TSSOP-24 package.
Device Information(1)
PART NUMBER PACKAGE
BODY SIZE (NOM)
UCC28950
TSSOP (24)
7.80 mm x 4.40 mm
(1) For all available packages, see the orderable addendum at the end of the datasheet.
+ VIN
CIN -
VSENSE
UCC28950 Typical Application
CT VBIAS
CREF R1
R2
UCC28950
1 VREF
GND 24
CVDD
VDD RLF2
2 EA+
VDD 23
R3
R6 R4 C3
C2
ENABLE
C1 R5
CSS RAB RCD
3 EA4 COMP 5 SS/EN 6 DELAB 7 DELCD
REF 8 DELEF
RTMIN RT
9 TMIN
VREF 10 RT
RSUM
11 RSUM
RDCMHI VREF 12 DCM
OUTA 22 .