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Using the UCC25710EVM-654

User's Guide

Literature Number: SLUU487A

March 2011–Revised March 2011

Summary of content (21 pages)

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Using the UCC25710EVM-654 User's Guide Literature Number: SLUU487A March 2011 – Revised March 2011
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User's Guide SLUU487A – March 2011 – Revised March 2011 98-W Resonant LLC, 4-String LED Driver 1 Introduction The UCC25710 Evaluation Module (EVM) was design to demonstrate how the UCC25710 could be used in a multi-transformer LLC half-bridge configuration for driving multiple strings of LEDs, in a high-efficiency application, for the back lighting of a digital TV, with Pulse With Modulation (PWM) dimming.
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Electrical Performance Specifications www.ti.com 3 Electrical Performance Specifications Table 1. UCC285710 EVM-654 Electrical Specifications PARAMETER MIN TYP MAX UNITS Input Characteristics VIN Input voltage IIN Input current 370 390 410 0.275 V A OUTPUT1, OUTPUT2, OUTPUT3, OUTPUT4 Characteristics VLED1, VLED2,VLED3, VLED4 Output voltage set by LED load ILED1, ILED2,ILED3, ILED4 Output current ripple ILED1, ILED2,ILED3, ILED4 Output current 0.245 0.25 0.
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Schematics + + + + + + + + + + + + Schematics + 4 www.ti.com Figure 1.
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Schematics www.ti.com Figure 2.
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Recommended Test Equipment www.ti.com 5 Recommended Test Equipment 5.1 Voltage Sources • • 5.2 Volt Meters • • 5.3 Capable of generating a 270-Hz to 330-Hz square wave with a 0-V to 5-V signal. Capable of duty cycles from 1% to 100% (DC). Network Analyzer • 5.5 Two Volt Meters Five Current Meters Square Wave Generator • • 5.4 500-V DC Source Capable of 150 W 0-V to 20-V DC Power Supply Capable of 2 W Needed to measure voltage loop stability if interested.
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Recommended Test Setups www.ti.com 6 Recommended Test Setups 500V DC Supply Volt Meter 1 Current Meter 5 J1 TP11 Volt Meter 5 TP2 J2 TP1 TP8 TP10 5V, 300Hz Square Wave Generator 100%,10% Duty Cycle Volt Meter 4 TP9 TP6 Volt Meter 3 5V TP14 TP7 TP4 0V Volt Meter 2 0 to 20V Bias Supply TP5 LED2 - LED4 - LED2 + TP17 LED4 + TP13 LED1 - LED1 + LED3 - LED3 + 4X 32 X (275mA LED Diode, Vf = 3.
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Recommended Test Setups www.ti.com 500V DC Supply Volt Meter 1 Current Meter 5 J1 J2 TP2 TP1 5V, 300Hz Square Wave Generator 100%,10% Duty Cycle Volt Meter 2 5V 0V TP14 TP5 0 to 20V Bias Supply LED2 LED1 - LED1 + LED2 + LED3 - LED4 LED3 + LED4 + TP13 TP17 32 X (1.1A LED Diode, Vf = 3.06V) Current Meter 4 Current Meter 3 D1 Current Meter 2 Current Meter 1 D32 Oscilloscope Current Probe Capable of Measuring2A Current Direction Figure 4.
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List of Test Points www.ti.com 7 List of Test Points Table 2.
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Test Data www.ti.com 9 Test Data 9.1 Current Matching With PWM Dimming The following table was taken with a 300-Hz PWM dimming frequency. Each LED output was loaded with 32 Cree XLamp XR-E diodes. At full load the current was controlled to a target current of 250 mA through each LED output string.
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Test Data www.ti.com 9.2 Efficiency Measuring efficiency with PWM dimming requires the use of power analyzers on the LED output/s. The following efficiency table was taken with LED voltage strings set to roughly 98 V. 98-W EFFICIENCY WITH PWM DIMMING 95 94 93 Efficiency - % 92 91 90 89 88 87 Efficiency 390 V 86 Efficiency 370 V Efficiency 410 V 85 10 25 40 70 55 85 100 Dimming - % Figure 8. Efficiency 10% to 100% PWM Dimming 9.
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Test Data 9.4 www.ti.com Zero Voltage Switching One of the major benefits of a LLC resonant half-bridge converter is the ability to achieve Zero Voltage Switching (ZVS) at the primary switch node. Figure 10 shows the primary transformer current (CH4), the current sense voltage (CH3), the switch node on the primary at the drain of FET Q2 (Q2g) and the gate drive signal to FET Q2 (Q2g). The gate drive signal going to FET Q1 is the inverse of CH1.
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Test Data www.ti.com 9.5 9.5.1 LED Current Startup Behavior (VIN = 390 V) Total LED Current = 1 A, Individual LED Current ≈ 0.25 A CH1 = V@R13 CH4 = (LED2 +) Current CH3 = (LED1 +) Current Figure 11. Current LED1 (CH3) and LED2 (CH4) CH1 = V@R13 CH4 = (LED4 +) Current CH3 = (LED3 +) Current Figure 12.
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Test Data 9.6 9.6.1 www.ti.com LED Current During 300-Hz PWM Dimming (VIN = 390 V) 90% PWM Dimming CH1 = V@R13 CH4 = (LED2 +) Current CH3 = (LED1 +) Current Figure 13. Current LED1 (CH3) and LED2 (CH4) CH1 = V@R13 CH4 = (LED4 +) Current CH3 = (LED3 +) Current Figure 14.
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Test Data www.ti.com 9.6.2 1% PWM Dimming, Peak LED Current ≈ 0.25 A CH1 = V@R13 CH4 = (LED2 +) Current CH3 = (LED1 +) Current Figure 15. Current LED1 (CH3) and LED2 (CH4) CH1 = V@R13 CH4 = (LED4 +) Current CH3 = (LED3 +) Current Figure 16.
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Assembly Drawings and Layout 10 www.ti.com Assembly Drawings and Layout Figure 17. Top Assembly TEXAS I NSTRUMENTS Figure 18.
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List of Materials www.ti.com 11 List of Materials Table 3. UCC25710EVM-654 98-W LLC 4-String LED Driver COUNT REF DES DESCRIPTION 5 C1, C6, C15, C22, C23 Capacitor, ceramic, 1 µF, 50 V, X7R, +/- 10%, 0805 8 C10, C11, C12, C13, C14, C16, C17, C18 Capacitor, aluminum, 10 µF ,160 V, +105°C, 20%, 10.00 ECA2CM100 mm Panasonic 1 C19 Capacitor, ceramic, 220 pF, 50 V, X7R, +/- 10%, 0805 Std Std 5 Capacitor, aluminum, 10 µF, 450 V, ±20%, 12.5 x 20.
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List of Materials www.ti.com Table 3. UCC25710EVM-654 98-W LLC 4-String LED Driver (continued) COUNT 18 REF DES DESCRIPTION PART NUMBER MFR 2 Q1, Q2 MOSFET, N-channel, 550 V, 10 A, 350 mΩ, TO-220V IPP50R350CP Infineon 1 Q3 Transistor, NPN, 40 V, 600 mA, TO 92 P2N2222A On Semi 1 Q4 Transistor, PNP, 60 V, 600 mA, TO 92 PN2907A "Micro Commercial Components 1 Q5 MOSFET, N-channel, 250 V, 51 A, 60 mΩ, TO-220V STD STD 2 R1, R9 Resistor, chip, 1.
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List of Materials www.ti.com Table 3. UCC25710EVM-654 98-W LLC 4-String LED Driver (continued) COUNT REF DES DESCRIPTION PART NUMBER MFR 1 T1 Transformer, gate drive, 0.453 x 0.492 inch 56PR3362 Vitec Electronics 4 T2, T3, T4, T5 Transformer 1:2, 1.213 x 1.276 inch 75PR8112 Vitec Electronics 1 T6 Current transformer 1:100, 0.495 x 0.495 inch 57PR3634 Vitec Electronics 18 TP1, TP2, TP3, TP4, TP5, TP6, TP7, TP8, TP9, Pin, thru hole, tin plate, for 0.062 PCB's, 0.
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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.
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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.