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Summary of Contents for Texas Instruments UCC2891
- Page 1 48-V to 3.3-V Forward Converter with Active Clamp Reset Using the UCC2891 Active Clamp Current Mode PWM Controller User's Guide December 2006 Power Supply MAN SLUU178A...
- Page 2 48-V to 3.3-V Forward Converter with Active Clamp Reset Using the UCC2891 Active Clamp Current Mode PWM Controller User's Guide Literature Number: SLUU178A November 2003 – Revised December 2006...
- Page 3 30 A of load current, operating from a 48-V input. The EVM operates over the full 36 V to 72 V telecom input range, and is able to fully regulate down to zero load current. The module uses the UCC2891 current mode active clamp PWM controller for effectively demonstrating the active clamp transformer reset technique.
- Page 4 Description Applications The UCC2891 is suited for use in isolated telecom 48-V input systems requiring high-efficiency and high-power density for very low-output voltage, high-current converter applications, including: Server Systems Datacom Telecom DSP's, ASIC's, FPGA's Features The UCC2891EVM features include: ZVS transformer reset using active clamp technique in forward converter All surface mount components, double sided half brick (2.2...
- Page 5 J8 is the output and return for the 3.3-V output voltage. On the primary side, U1 is the UCC2891 shown with the necessary discrete circuitry for configuring the controller to operate at 300 kHz with the maximum duty clamp set for 0.65. The EVM is programmed to start at VIN=36 V, as determined by R11 and R12.
- Page 6 Schematic Figure 1. UCC2891EVM Schematic Using the UCC2891 Active Clamp Current Mode PWM Controller SLUU178A – November 2003 – Revised December 2006 Submit Documentation Feedback...
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Page 7: Evm Test Setup
SLUU178A – November 2003 – Revised December 2006 Submit Documentation Feedback +VOUT +Vout -Vout -VOUT SR-QF Gate SR-QR Gate Loop+ Loop- Texas Instruments HPA034 UCC2891 Active Clamp Converter Using the UCC2891 Active Clamp Current Mode PWM Controller EVM Test Setup LOAD1 3.3V/30A... - Page 8 200-400 LFM is recommended to reduce component temperatures when operating at or above 50% maximum rated load current. Using the UCC2891 Active Clamp Current Mode PWM Controller , is used. Using a dc voltmeter, V2, it is also advised to make all output Figure 2.
- Page 9 , the fan should be turned on. Also, never Figure 2. Set LOAD1 to constant current mode to sink 0 A Figure to 30 A to 0 V. Using the UCC2891 Active Clamp Current Mode PWM Controller Power Up/Down Test Procedures Figure Figure before...
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Page 10: Output Current
= 3.3 V = 300 kHz = 72 V = 36 V - Output Current - A Figure 4. Using the UCC2891 Active Clamp Current Mode PWM Controller OVERALL EFFICIENCY OUTPUT CURRENT = 48 V = 72 V = 36 V - Output Current - A Figure 3. - Page 11 = 72 V = 30 A -120 -180 100 k t − Time − 2.5 s/div Using the UCC2891 Active Clamp Current Mode PWM Controller Power Up/Down Test Procedures 500 mV/div 1 V peak-to-peak t − Time − 2.5 s/div Figure 8.
- Page 12 = 48 V = 10 A (0.5 A/div) t − Time − 2.5 s/div Figure 11. Using the UCC2891 Active Clamp Current Mode PWM Controller = 36 V 6.3 V, QF Gate (J5) (5 V/div) 50 mV/div 8.4 V, QR Gate (J6)
- Page 13 SLUU178A – November 2003 – Revised December 2006 Submit Documentation Feedback show the top-side and bottom-side component placement for the EVM, as Using the UCC2891 Active Clamp Current Mode PWM Controller EVM Assembly Drawing and Layout Figure 15. All components are...
- Page 14 EVM Assembly Drawing and Layout Figure 15. Top Side Silk Screen Figure 16. Top Signal Trace Layer Using the UCC2891 Active Clamp Current Mode PWM Controller SLUU178A – November 2003 – Revised December 2006 Submit Documentation Feedback...
- Page 15 EVM Assembly Drawing and Layout Figure 17. Internal Split Ground Plane Figure 18. Internal Signal Trace Layer SLUU178A – November 2003 – Revised December 2006 Using the UCC2891 Active Clamp Current Mode PWM Controller Submit Documentation Feedback...
- Page 16 EVM Assembly Drawing and Layout Figure 19. Bottom Signal Trace Layer Figure 20. Bottom Side Component Assembly Using the UCC2891 Active Clamp Current Mode PWM Controller SLUU178A – November 2003 – Revised December 2006 Submit Documentation Feedback...
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Page 17: List Of Materials
Vishay Vishay Sanyo Vishay Philips/NXP Vishay 0.35 Mill Max 0.35 0.780 Pulse Vishay Renesas Vishay Using the UCC2891 Active Clamp Current Mode PWM Controller List of Materials PART NUMBER C4532X7R2A225M VJ0805Y104MXAA VJ0805A101KXAA C2012X7R1H224M VJ0805Y103MXAA GRM31CR72E333KW03L 595D476X9016C2T C3216X5R1C106M C2012X5R1A155M VJ0805Y823KXAA VJ0805A221KXAA... - Page 18 IC, phototransistor, CTR 100%-300%, SOP-4 References 1. UCC2891 Current Mode Active Clamp PWM Controller, Datasheet, (SLUS542) 2. Designing for High Efficiency with the UCC2891 Active Clamp PWM Controller, by Steve Mappus, Application Note (SLUA299) Using the UCC2891 Active Clamp Current Mode PWM Controller Table 2.
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Page 19: Evm Important Notice
EVM IMPORTANT NOTICE Texas Instruments (TI) provides the enclosed product(s) under the following conditions: This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not considered by TI to be fit for commercial use. As such,... - Page 20 EVM schematic located in the EVM User’s Guide. When placing measurement probes near these devices during operation, please be aware that these devices may be very warm to the touch. Copyright © 2003--2006, Texas Instruments Incorporated Mailing Address: Texas Instruments...
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Page 21: Important Notice
TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated products in automotive applications, TI will not be responsible for any failure to meet such requirements. Following are URLs where you can obtain information on other Texas Instruments products and application solutions: Products Amplifiers amplifier.ti.com...
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