Page 2 - Literature Number: SLUU178A
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 - Using the UCC2891 Active Clamp Current Mode PWM; Using the UCC2891 Active Clamp Current Mode PWM Controller
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 at30 A of load current, operating from a 48-V input. ...
Page 4 - Description
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 andhigh-power density for very low-output voltage, high-current converter applications, including: • Server Systems • Datacom • Telecom • DSP's, ASIC's,...
Page 5 - UCC2891EVM Electrical Performance Specifications; Table 1; Table 1. UCC2891EVM Performance Summary; A schematic of the UCC2891EVM is shown in
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 Characteri...
Page 6 - Schematic
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
Page 7 - DANGER HIGH VOLTAGE; EVM Test Setup; Figure 2; Figure 2. Recommended EVM Test Configuration
www.ti.com 5 EVM Test Setup V 2 - + J1 +V out -V out J9 J10 Loop+ Loop- J6 J7 Texas InstrumentsHPA 034UCC2891 A ctive Clamp Converter J3 V -Clamp J2 Q2 Gate J4 SR-QF Gate J5 SR-QR Gate LOA D1 3.3V /30A - + A 1 V IN - + V 1 FA N + + - - - + +V IN -V IN DANGER HIGH VOLTAGE +V OUT -V OUT J8 EVM Test Se...
Page 9 - Power Up/Down Test Procedures
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 fo...
Page 10 - rc; GAIN AND PHASE
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 P e rc e n t E ff ic ie n c y - % V OUT = 3.3 V f S = 300 kHz OVERALL EFFICIENCY vs OUTPUT CURRENT 10 -40 -60 100 1 k 10 k 100 k 0 -20 40 20 60 -120 -1...
Page 11 - Input Ripple Voltage; Output Ripple Voltage
www.ti.com t − Time − 2.5 µ s/div V IN = 36 V I OUT = 30 A 500 mV/div 1 V peak-to-peak Input Ripple Voltage 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 G a in - d B P h a s e - ° GAIN AND PHASE ...
Page 12 - SR Gate Drive; SR Gate Drive
www.ti.com t − Time − 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 − Time − 2.5 µ s/div V IN = 36 V I OUT = 30 A 50 mV/div 23 mV peak-to-peak Output Ripple Voltage t − Time − 1 µ s/div V IN = 72 V 12.3 V, QF Gate (J5)(5 V/div) 5.4 V, QR Gate (J6)(5 ...
Page 13 - EVM Assembly Drawing and Layout; through; Figure 14. Top Side Component Assembly
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 bottomlayers for signal traces an...
Page 14 - Figure 15. Top Side Silk Screen
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
Page 15 - Figure 17. Internal Split Ground Plane
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
Page 16 - Figure 19. Bottom Signal Trace Layer
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
Page 17 - List of Materials; Figure 1; Table 2. List of Materials; QT
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 C...
Page 18 - References
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%, 80...
Page 19 - EVM IMPORTANT NOTICE; This evaluation kit being sold by TI is intended for use for; ENGINEERING DEVELOPMENT OR; and is not considered by TI to be fit for commercial use. As such,; is not exclusive; TI assumes
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, the goods b...
Page 20 - DYNAMIC WARNINGS AND RESTRICTIONS; C as long as
DYNAMIC WARNINGS AND RESTRICTIONS It is important to operate this EVM within the input voltage range of 0 Vdc to 72 Vdc. Exceeding the specified input range may cause unexpected operation and/or irreversible damageto the EVM. If there are questions concerning the input range, please contact a TI fie...
