Using the UCC2897A-EVM User's Guide Literature Number: SLUU357 November 2009
User's Guide SLUU357 – November 2009 48-V to 3.3-V Forward Converter with Active Clamp Reset Using the UCC2897A Active Clamp Current Mode PWM Controller 1 Introduction The UCC2897A evaluation module (EVM) is an active clamp reset forward converter providing a 3.3-V regulated output at 30 A of load current, operating from a 48-V input. The design operates over the full 36-V to 72-V telecom input range, and is able to fully regulate down to zero load current.
Description www.ti.com 2.1 Typical Applications 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 2.2 Features • • • • • • • • • • • • • • ZVS transformer reset using active clamp technique in forward converter. All surface mount components, double sided half brick (2.2” x 2.28” x 0.5”).
Electrical Performance Specifications 3 www.ti.com Electrical Performance Specifications Table 1. Electrical Performance Specifications PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Input Characteristics Input voltage range No load input current 36 VIN = 36 V, IOUT = 0 A 48 72 V 75 100 mA Input undervoltage limit 35 Input overvoltage limit 73 V Max input current VIN = 36 V, IOUT = 30 A 3 3.25 A Input voltage ripple VIN = 72 V, IOUT = 30 A 1.5 1.
Schematic www.ti.com Schematic + + 4 Figure 1. UCC2897A-EVM Schematic SLUU357 – November 2009 Submit Documentation Feedback 48-V to 3.
Test Setup 5 Test Setup 5.1 Test Equipment www.ti.com Voltage Source, VIN: The input voltage shall be a variable DC source capable of supplying between 0 VDC and 75 VDC at no less than 3.5 ADC, and connected to J1 and A1 as shown in Figure 2. For fault protection to the unit, good common practice is to limit the source current to no more than 3.5 ADC for a 36-V input. A DC ammeter, A1 should also be inserted between VIN and J1 as shown in Figure 2.
Test Setup www.ti.com 5.2 Recommended Test Setup + Vin Source - V1 Load1 3.3V30A A1 + V2 FAN Figure 2. Recommended Test Set Up SLUU357 – November 2009 Submit Documentation Feedback 48-V to 3.
Power Up/Down Procedure 6 www.ti.com Power Up/Down Procedure 1. Working at an ESD workstation, make sure that any wrist straps, bootstraps or mats are connected referencing the user to earth ground before power is applied to the unit. electrostatic smock and safety glasses should also be worn. 2. Prior to connecting the DC input source, VIN, it is advisable to limit the source current from VIN to 3.5 A maximum. Make sure VIN is initially set to 0 V and connected to J1 as shown in Figure 2. 3.
Performance Data and Typical Characteristic Curves www.ti.com 7 Performance Data and Typical Characteristic Curves through present typical performance curves for UCC2897A-EVM. 100 3.35 VO U T - O u tpu t V o ltag e - V Ð - Efficiency - % 90 80 70 60 3.33 3.31 3.29 3.27 50 36.0 V 48.0 V 36.0 V 72.0 V 48.0 V 72.0 V 3.25 40 0 5 10 15 IOUT - Load Current - A 20 25 30 0 5 10 15 20 25 30 IOUT - Load Current - A Figure 3. UCC2897A-EVM Efficiency Figure 4.
Performance Data and Typical Characteristic Curves 10 www.ti.com Figure 9. 10-A Load with 5-A Transient Figure 10. Output Ripple, (24mVpp, noise 151.2mVpp) Figure 11. Synchronous Rectifier Gate Drive (VIN = 36 V) Figure 12. Synchronous Rectifier Gate Drive (VIN = 72 V) 48-V to 3.
Performance Data and Typical Characteristic Curves www.ti.com Figure 13. Turn-On Waveform 30 V in a 30-A Load Figure 14. Power Off Waveform Figure 15. Q1 and Q2 Gate to Source Voltage VIN = 48 V, IOUT = 10 A SLUU357 – November 2009 Submit Documentation Feedback 48-V to 3.
EVM Assembly Drawing and PCB Layout 8 www.ti.com EVM Assembly Drawing and PCB Layout Figures Figure 16 through Figure 21 show the design of the UCC2897A-EVM printed circuit board. The PCB is a four-layer board using 4-oz copper on all layers. Figure 16. Top Layer Assembly Drawing (top view) 12 48-V to 3.
EVM Assembly Drawing and PCB Layout www.ti.com Figure 17. Bottom Assembly Drawing (bottom view) SLUU357 – November 2009 Submit Documentation Feedback 48-V to 3.
EVM Assembly Drawing and PCB Layout www.ti.com Figure 18. Top Copper (top view) 14 48-V to 3.
EVM Assembly Drawing and PCB Layout www.ti.com Figure 19. Internal Layer 1 (top view) SLUU357 – November 2009 Submit Documentation Feedback 48-V to 3.
EVM Assembly Drawing and PCB Layout www.ti.com Figure 20. Internal Layer 2 (top view) 16 48-V to 3.
EVM Assembly Drawing and PCB Layout www.ti.com Figure 21. Bottom Copper (top view) SLUU357 – November 2009 Submit Documentation Feedback 48-V to 3.
List of Materials 9 www.ti.com List of Materials Table 2. EVM Components (shown in Figure 1) COUNT 18 REF DES DESCRIPTION PART NUMBER MFR 3 C1, C2, C4 Capacitor, ceramic, 2.2 µF, 100 V, X7R, 20%, 1812 C4532X7R2A225M TDK 2 C10, C12 Capacitor, ceramic, 16 V, X5R, 20%, 10 µF, 1206 std std 0 C11 Capacitor, ceramic, vvV, [temp], [tol], open, 1210 Std Vishay 1 C13 Capacitor, ceramic, 25 V, X5R, 10%, 2.
List of Materials www.ti.com Table 2. EVM Components (shown in Figure 1) (continued) COUNT REF DES DESCRIPTION PART NUMBER MFR 2 R25, R30 Resistor, chip, 1/8 W, 1%, 51.1 Ω, 0805 std std 1 R26 Resistor, chip, 1/8 W, 1%, 28.7 kΩ, 0805 std std 1 R27 Resistor, chip, 1/8 W, 1%, 12.1 kΩ, 0805 std std 1 R28 Resistor, chip, 1/8 W, 1%, 4.99 kΩ, 0805 std std 1 R3 Resistor, chip, 1/8 W, 1%, 88.
List of Materials www.ti.com Table 3. EVALUATION BOARD/KIT IMPORTANT NOTICE Texas Instruments (TI) provides the enclosed product(s) under the following conditions: This evaluation board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY and is not considered by TI to be a finished end-product fit for general consumer use. Persons handling the product(s) must have electronics training and observe good engineering practice standards.
IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.
