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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 ...
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Texas Instruments UCC2891 - 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 ...
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Texas Instruments UCC2891 - page 3
1 Introduction 2 Description User's Guide SLUU178A – November 2003 – Revised December 2006 Using the UCC2891 Active Clamp Current Mode PWM Controller The UCC2891EVM evaluation module (EVM) is a forward converter providing a 3.3-V regulated output at 30 A of load current, operating from a 48-V input. The EVM operates over the full 36 V to 7 ...
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Texas Instruments UCC2891 - page 4
www.ti.com 2.1 Applications 2.2 Features Description 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 The UCC2891EVM fea ...
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Texas Instruments UCC2891 - page 5
www.ti.com 3 UCC2891EVM Electrical Performance Specifications 4 Schematic UCC2891EVM Electrical Performance Specifications The UCC2891EVM electrical performance specifications are listed in Table 1 . Table 1. UCC2891EVM Performance Summary PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Input Characteristics Input voltage range 36 48 72 V No load intpu ...
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Texas Instruments UCC2891 - page 6
www.ti.com + + + + Schematic Figure 1. UCC2891EVM Schematic 6 Using the UCC2891 Active Clamp Current Mode PWM Controller SLUU178A – November 2003 – Revised December 2006 Submit Documentation Feedback ...
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Texas Instruments UCC2891 - page 7
www.ti.com 5 EVM Test Setup V 2 - + J 1 + V out -V out J 9 J 10 Loo p+ Loo p- J 6 J 7 T exas I ns trum e nts H P A 03 4 U C C 2891 A c ti v e C l am p C onver te r J 3 V -C l am p J 2 Q 2 G ate J 4 SR -Q F G ate J 5 SR -Q R G ate LO A D 1 3.3V/30A - + A 1 V I N - + V 1 F A N + + - - - + + V I N -V I N DA NG E R HI GH V OL T A GE + V O U T -V OU T J ...
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Texas Instruments UCC2891 - page 8
www.ti.com 5.1 Output Load (LOAD1) 5.2 DC Input Source (VIN) 5.3 Network Analyzer 5.4 Recommended Wire Guage 5.5 Fan EVM Test Setup For the output load to VOUT, a programmable electronic load set to constant current mode and capable of sinking between 0A DC and 30A DC , is used. Using a dc voltmeter, V2, it is also advised to make all output voltag ...
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Texas Instruments UCC2891 - page 9
www.ti.com 6 Power Up/Down Test Procedures Power Up/Down Test Procedures The following test procedure is recommended primarily for power up and shutting down the EVM. Whenever the EVM is running above an output load of 15 A DC , the fan should be turned on. Also, never walk away from a powered EVM for extended periods of time. 1. Working at an ESD ...
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Texas Instruments UCC2891 - page 10
www.ti.com 7 Power Up/Down Test Procedures 81 79 87 83 91 89 93 85 2 6 18 26 22 10 14 I OUT - Output Current - A V IN = 36 V V IN = 72 V V IN = 48 V Percent Efficiency - % V OUT = 3.3 V f S = 300 kHz OVERA LL EFFICIENCY vs OUTPUT CURRENT 10 -40 -60 100 1 k 10 k 100 k 0 -20 40 20 60 -120 -180 0 -60 120 60 180 V IN = 36 V I OUT = 10 A g M = -8 dB F M ...
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Texas Instruments UCC2891 - page 11
www.ti.com t − T ime − 2.5 µ s/div V IN = 36 V I OUT = 30 A 500 mV/div 1 V peak-to-peak Input Ripple V oltage 10 -40 -60 100 1 k 10 k 100 k 0 -20 40 20 60 -120 -180 0 -60 120 60 180 V IN = 48 V I OUT = 10 A g M = -10 dB F M = 50° Gain Phase f - Frequency - Hz Gain - dB Phase - ° GAIN A ND PHA SE vs FREQUENCY t − T ime − 2.5 µ s/div V IN ...
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Texas Instruments UCC2891 - page 12
www.ti.com t − T ime − 1 µ s/div V IN = 36 V 6.3 V , QF Gate (J5) (5 V/div) 8.4 V , QR Gate (J6) (5 V/div) SR Gate Drive t − T ime − 2.5 µ s/div V IN = 36 V I OUT = 30 A 50 mV/div 23 mV peak-to-peak Output Ripple V oltage t − T ime − 1 µ s/div V IN = 72 V 12.3 V , QF Gate (J5) (5 V/div) 5.4 V , QR Gate (J6) (5 V/div) SR Gate Drive t ...
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Texas Instruments UCC2891 - page 13
www.ti.com 8 EVM Assembly Drawing and Layout EVM Assembly Drawing and Layout Figure 14 through Figure 20 show the top-side and bottom-side component placement for the EVM, as well as device pin numbers where necessary. A four layer PCB was designed using the top and bottom layers for signal traces and component placement along with an internal grou ...
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Texas Instruments UCC2891 - page 14
www.ti.com EVM Assembly Drawing and Layout Figure 15. Top Side Silk Screen Figure 16. Top Signal Trace Layer 14 Using the UCC2891 Active Clamp Current Mode PWM Controller SLUU178A – November 2003 – Revised December 2006 Submit Documentation Feedback ...
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Texas Instruments UCC2891 - page 15
www.ti.com 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 15 Submit Documentation Feedback ...
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Texas Instruments UCC2891 - page 16
www.ti.com 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 16 SLUU178A – November 2003 – Revised December 2006 Submit Documentation Feedback ...
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Texas Instruments UCC2891 - page 17
www.ti.com 9 List of Materials List of Materials The following table lists the UCC2891EVM components corresponding to the schematic shown in Figure 1 . Table 2. List of Materials QT REF DESCRIPTION MFR PART NUMBER Y C1, C2, C4 3 Capacitor, ceramic, 2.2 µ F, 100 V, X7R, 20%, 1812 TDK C4532X7R2A225M C3, C14, C17 3 Capacitor, ceramic, 0.1 µ F, 50 V, ...
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Texas Instruments UCC2891 - page 18
www.ti.com 10 References References Table 2. List of Materials (continued) QT REF DESCRIPTION MFR PART NUMBER Y R1 1 Resistor, chip, 8.45 k Ω , 1/10 W, 1%, 805 Vishay CRCW0805-8451-F R2 1 Resistor, chip, 57.6 k Ω , 1/10 W, 1%, 805 Vishay CRCW0805-5762-F R3 1 Resistor, chip, 76.8 k Ω , 1/10 W, 1%, 805 Vishay CRCW0805-7682-F R4, R10, R15, R16, ...
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Texas Instruments UCC2891 - page 19
EVM IMPORT ANT NOTICE T exas Instr ument s (TI) provi des the encl osed product (s) under the f oll owing condi ti ons: This eval uati on kit bei ng sold by TI is i ntended for use for ENGI NEERING DEVELOPMENT OR EV ALUA TION PURPOSES ONL Y and is not considered by TI to be fi t f or commer cial use. As such, the goods bei ng provi ded may not be c ...
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Texas Instruments UCC2891 - page 20
DYNAMIC W ARNINGS AND RESTRICTI ONS It is impor tant to oper ate thi s EVM wit hin t he input voltage r ange of 0 Vdc t o 72 Vdc. Exceeding t he specif ied input r ange may cause unexpected oper ati on and/or i rr eversi ble damage to the EVM. If ther e are questi ons concerning t he input r ange, please contact a TI fiel d repr esentat ive pr ior ...
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