P A T E N T P LIN D O C #: 1590 E N D I N G LXM1590/LXM1591 C USTOMIZABLE CCFL IN V E RTER MODULES T H E I N F I N I T E P O W E R O F I P N N O VA T I O N R E L I M I N A R Y DESCRIPTION LXM1590 series CCFL (cold cathode fluorescent lamp) Inverter Modules are specifically designed for driving LCD back light lamps in portable computers wher e dimmability, ultrahigh efficiency, low noise emissions, reliable fail safe design, and small form factors are critical parameters. Mechanical form factors and electrical characteristics can be customized for volume applications. Both monochrome and color displays with either one or two lamps are supported. The modules convert unregulated DC voltage from the system battery or AC adapter directly to high-frequency, highvoltage sine waves required to ignite and operate CCFL lamps. The module design is based on a proprietary Linfinity IC that provides important new performance advances. Remarkable improvements in efficiency and RF emissions result from its single stage resonant inverter featuring a patent pending Current Synchronous, Zero Voltage Switching (CS-ZVS) topology. CS-ZVS produces nearly pure sine wave currents in the lamp enabling maximum light delivery while reducing both conducted and radiated noise. This topology simultaneously performs three tasks consisting of line voltage regulation, lamp current regulation, and lamp dimming in a single power stage made up of one or two pairs of low loss FET's. The FET's drive an LC resonant circuit that feeds the primary of a high voltage transformer with a sinusoidal voltage. Required L and C values in the resonant circuit are such that very low loss components can be used to obtain higher electrical efficiency than is possible with previous topologies. Two module versions are available. The half bridge LXM1590 provides peak efficiency when operated with less than 2 watt lamps at input voltages above 6 volts. The LXM1591 achieves higher efficiency at higher output power levels and lower input voltages with its full bridge drive circuit. The modules are equipped with a dimming input that permits full range brightness control from an external potentiometer, and a sleep input that reduces module power to a few microwatts in shut down mode. All modules feature output open and short circuit protection. MEASURED LIGHT OUTPUT VS . POWER INPUT FOR LXM1590 P OPULAR R OYER OSCILLATOR INVERTER WITH DIMMING CONTROL AND A Output Light / Input Power - Lux/Watt 2.0 35% More Light 60% More Light 1.5 S H E E T ■ 35% MORE LIGHT OUTPUT AT 2.5 WATTS ■ CLOSED LOOP, FULLY REGULATING DESIGN ■ 4.5V TO 30V INPUT VOLTAGE RANGES ■ VERSATILE BRIGHTNESS CONTROL INPUT ■ 3 MICROAMP SLEEP CURRENT ■ OUTPUT SHORT CIRCUIT PROTECTION AND AUTOMATIC OVER VOLTAGE LIMITING ■ 8mm MAX HEIGHT, NARROW FOOTPRINTS ■ SINGLE SIDED PCB IS SELF INSULATING A P P L I C AT I O N S ■ NOTEBOOK AND SUB-NOTEBOOK COMPUTERS ■ PERSONAL DIGITAL ASSISTANTS ■ PORTABLE INSTRUMENTATION ■ AUTOMOTIVE DISPLAYS ■ DESKTOP DISPLAYS ■ AIRLINE ENTERTAINMENT CENTERS BENEFITS ■ ULTRA-HIGH EFFICIENCY, LINE VOLTAGE REGULATION AND SLEEP MODE EXTEND COMPUTER BATTERY LIFE ■ COOL OPERATION PERMITS CLOSE PROXIMITY TO LCD PANEL WITHOUT DISPLAY DISTORTION ■ SMOOTH, FULL-RANGE BRIGHTNESS CONTROL GIVES YOUR PRODUCT A HIGH QUALITY IMAGE ■ LOW EMI / RFI DESIGN MINIMIZES SHIELDING REQUIREMENTS LXM1590 ■ NARROW, LOW PROFILE STANDARD MODULES FIT INTO MOST LCD ENCLOSURES Dimmable Royer Oscillator 1.0 A T A K E Y F E AT U R E S PRODUCT HIGHLIGHT 45% More Light D ■ SINGLE SIDED PCB SAVES EXPENSIVE HIGH VOLTAGE INSULATING TAPES 0.5 CCFL = JKL P/N BF6225 VIN = 10VDC 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Input Power - Watts M O D U L E O R D E R I N F O R M AT I O N HALF BRIDGE DRIVE FULL BRIDGE DRIVE LXM1590-xxxxx-zz LXM1591-xxxxx-zz See instructions inside for completing module part number. F O R F U R T H E R I N F O R M AT I O N C A L L ( 7 1 4 ) 8 9 8 - 8 1 2 1 Copyright © 1995 Rev. 0.9.3 3/96 11861 WESTERN A VENUE , G ARDEN G ROVE , CA. 92841 1 P AT E N T P E N D I N G PRODUCT DATABOOK 1996/1997 LXM1590/LXM1591 C USTOMIZABLE CCFL IN V E RTER MODULES P R E L I M I N A R Y D A T A S H E E T A B S O L U T E M A X I M U M R AT I N G S (Note 1) Input Supply Voltage (VIN)......................................................................................... LXM1590 = -0.3V to 30V/ LXM1591 = -0.3 to 7.0V Output Voltage, no load .............................................................................................................................. Internally Limited to 1900VRMS Output Current .............................................................................................................................................. 8.0mARMS (Internally Limited) Output Power ........................................................................................................................................................................................ 4.2W Input Signal Voltage, (SLEEP and BRITE Inputs) .................................................................................................................. -0.3V to 6.5V Ambient Operating Temperature, zero airflow ........................................................................................................................ 0°C to 60°C Storage Temperature Range ................................................................................................................................................... -40°C to 85°C Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal. R E C O M M E N D E D O P E R A T I N G C O N D I T I O N S (R.C.) This module has been designed to operate over a wide range of input and output conditions. However, best efficiency and performance will be obtained if the module is operated under the condition listed in the 'R.C.' column. Min. and Max. columns indicate values beyond which the inverter, although operational, will not function optimally. Parameter Symbol Input Supply Voltage LXM1590 LXM1591 Output Power Brightness Control Input Voltage Range Lamp Operating Voltage Lamp Current - Full Brightness Operating Ambient Temperature Range VIN PO VBRITE VLAMP IOLAMP TA Recommended Operating Conditions Min. R.C. Max. 7 4.5 12 30 6.5 4.0 2.5 650 7 60 2.5 0.8 240 Units 500 5 0 V V W V VRMS mA RMS °C ELECTRICAL CHARACTERISTICS Unless otherwise specified, these specifications apply over the recommended operating conditions and 25°C ambient temperature for the LXM1590/1591. Parameter Symbol Test Conditions LXM1590/1591 Min. Typ. Max. Units Output Pin Characteristics Full Bright Lamp Current Minimum Lamp Current Lamp Start Voltage Operating Frequency IL (MAX) IL (MIN) VLS fO VBRITE = 2.5 V DC, SLEEP = Logic High VBRITE = 0.9 V DC, SLEEP = Logic High 0°C < TA < 60°C VBRITE = 2.5VDC, SLEEP = Logic High, VIN = 12V 6.2 6.6 2.6 7.0 mA mA RMS VRMS KHz -1000 2.6 nADC VDC VDC 50 5.5 0.8 100 VDC VDC µADC 2.50 2.60 VDC µADC 3 92 90 10 µADC % % 1300 50 Brightness Control Input Current Input Voltage for Max. Lamp Current Input Voltage for 50% Lamp Current IBRITE VC VC VBRITE = 0V DC IO (LAMP) = 100% IO (LAMP) = 50% 2.4 -200 2.5 1.25 SLEEP Input Input Logic 1 Input Logc 0 Input Current VIH VIL IIN 2.2 0 VSLEEP = 0 - 5VDC Voltage Reference Output Voltage Output Current V REF IREF 0 < IREF < 500µA 2.40 500 Power Characteristics Sleep Current Electrical Efficiency (calculated values) 2 IIN (MIN) η VIN = 5VDC , SLEEP = Logic 0 LXM1590, VIN = 12VDC, IO (LAMP) = 5mARMS LXM1591, VIN = 5VDC, IO (LAMP) = 5mARMS Copyright © 1995 Rev. 0.9.3 3/96 PRODUCT DATABOOK 1996/1997 P AT E N T P E N D I N G LXM1590/LXM1591 C USTOMIZABLE CCFL IN V E RTER MODULES P R E L I M I N A R Y D A T A S H E E T FUNCTIONAL PIN DESCRIPTION Conn. CN1 Pin Description CN1-1 CN1-2 VIN Input voltage. (+7 to +30VDC ) CN1-3 CN1-4 GND Power supply return. CN1-5 SLEEP Logical high on this pin enables inverter operation. Logical low removes power from the module and the lamp. A floating input is sensed as a logical low and will disable inverter operation. If not used, connect SLEEP through a 33kΩ resistor to VIN or directly to any voltage between 2.5 and 7V. May be used to modulate lamp intensity by varying duty cycle. CN1-6 BRITE Brightness control input. Apply 0.9 to 2.5 volts DC to control lamp brightness. Lamp current varies linearly with input voltage. Open circuit or 2.5V gives maximum brightness. CN1-7 AGND Brightness control signal return. For best results do not run VIN power supply current return through this pin. CN1-8 VREF Reference Voltage Output. 2.5V @ 500µA max. For use with external dimming circuit. CN2-1 LAMP HI High voltage connection to high side of lamp. Connect to lamp terminal with shortest lead length. Do not connect to ground. CN2-2 LAMP LO High voltage connection to low side of lamp. Connect to lamp terminal with longer lead length. Do not connect to ground. CN2 Copyright © 1995 Rev. 0.9.3 3/96 3 P AT E N T P E N D I N G PRODUCT DATABOOK 1996/1997 LXM1590/LXM1591 C USTOMIZABLE CCFL IN V E RTER MODULES P R E L I M I N A R Y D S A T A H E E T CCFL INVERTER EFFICIENCY - THE EVOLUTION CONTINUES 1.03 1.02 Relative Efficiency 1.01 POUT = 1.7W 1.00 1.03 1.02 1.01 0.99 1.00 POUT = 1.7W 0.99 0.98 0.97 POUT = 3.4W 0.96 0.95 0.94 0.93 4 4.5 5.5 5 6 VIN - Input Voltage - (V) FIGURE 3. — LIGHT OUTPUT vs. POWER INPUT 5 VIN = 10V CCFL = JKL P/N BF6225 4 Light Output - Lux FIGURE 1. — RELATIVE EFFICIENCY vs. VIN FOR THE LXM1590 FIGURE 2. — RELATIVE EFFICIENCY vs. VIN FOR THE LXM1591 Relative Efficiency Portable computing is dependent on low power flat panel LCD display technology. Each new shrinking of computer size and weight has resulted in exponential market growth. New LCD's with richer color now promise yet another order of magnitude growth in notebook sized machines. Great looking color displays need lots of light, more than monochrome displays. The power to generate that light must come from the system battery. But the battery cannot grow in size and weight, so the conversion from battery power to visible light must be made more efficient. The LXM1590/1591 modules are the latest evolution in inverter technology and represent the most efficient method yet, generating 35% to 60% more light from a CCFL tube than today's most popular solutions¹. Present technologies are based on the venerable Royer oscillator circuit enhanced with various types of voltage regulator circuits that permit operation from an unregulated battery input and enable the dimming function needed in portable computers. Figures 1 and 2 below characterize relative efficiency over a broad range of input voltage and at typical one and two lamp CCFL output power levels. Figure 3 compares actual light outputs of the LXM1591 module at various battery power levels with a popular dimmable Royer oscillator based solution. The data in Figure 3 was measured in a specially built and carefully calibrated fixture using the same physical CCFL tube for both circuits. Lamp current and voltage of the test CCFL is typical of single tube notebook display applications. The actual amount of light output from the lamp you are using may differ from this curve, but the relative increase in performance over the Royer based circuit will remain. LXM1590 3 2 Dimming Royer Oscillator 1 0.98 POUT = 3.0W 0.97 0 0.96 0 0.95 1 2 3 Power Inputs - Watts 0.94 Note: 1 Lux = 1 Lm/m² = 1 Lumen/meter² = 10.76 foot candles. 0.93 5 10 15 20 25 VIN - Input Voltage - (V) ¹ See "A New and Improved Control Technique Greatly Simplifies The Design Of Highly Efficient Dimming CCFL Backlight Inverter Circuits". Nalbant, LMI, 1994 4 Copyright © 1995 Rev. 0.9.3 3/96 PRODUCT DATABOOK 1996/1997 P AT E N T P E N D I N G LXM1590/LXM1591 C USTOMIZABLE CCFL IN V E RTER MODULES P R E L I M I N A R Y D A T A S H E E T T Y P I C A L A P P L I C AT I O N S AC/DC Adapter VIN VREF LAMP HI R1 100k Sytem Battery (NiCd, NiMH, etc.) BRITE LXM1590/91 3.3 or 5V From Power Management Logic SLEEP CMOS or TTL R2 56k LAMP LO AGND GND CFL TUBE Inside LCD Panel FIGURE 4. — NOTEBOOK SYSTEM APPLICATION CMOS or TTL gate From Power Management Logic VIN SLEEP VREF R1 BRITE Lamp Current (%) = LAMP HI CFL TUBE LXM1590/91 R2 LAMP LO AGND VBRITE x 100 VREF R1 = 100k typical, 5k minimum R2 = Value optional to determine lowest brightness setting R2 = 0.5 R1 minimum GND Longest Lead FIGURE 5. — POTENTIOMETER BRIGHTNESS CONTROL & SLEEP MODE +5V S1 "Increase" +5V U1 47k N.O. UC From Logic (optional) D N.O. S2 "Decrease" 47k DC RH VREF RW RL BRITE R1 AGND LXM1590/91 • S1 & S2 are momentary push buttons, normally open contacts. • U1 = Dallas Semiconductor DS1669100, 100k digital pot. • R1 value optional for choosing dimming range: for R1 = 100k, Range = 100% to 50% for R1 = 50k, Range = 100% to 33% • R1 minimum value is 0.5 RPOT. +5V FIGURE 6. — NON-VOLATILE DIGITAL BRIGHTNESS CONTROL Copyright © 1995 Rev. 0.9.3 3/96 5 PRODUCT DATABOOK 1996/1997 P AT E N T P E N D I N G LXM1590/LXM1591 C USTOMIZABLE CCFL IN V E RTER MODULES P R E L I M I N A R Y D S A T A T Y P I C A L A P P L I C AT I O N S R1 100k BRITE A Logic Inputs R3 402k (continued) • Drivers are open collector. • Run separate ground from driver chip to LXM1590/91 AGND to prevent noise pickup. VREF R2 150k H E E T • This scheme may be expanded to 3 or 4 bits for more resolution. Lamp Current (% Full On) = AGND LXM1590/91 B VBRITE x 100 VREF A B Lamp Current 0 0 1 1 0 1 0 1 52% 60% 80% 100% FIGURE 7. — LOW COST DIGITAL BRIGHTNESS CONTROL 1kHz Standard CMOS Gate 100k 20k 1N914 Brightness (% Full On) = VREF BRITE 1µF VBRITE x 100 VREF AGND LXM1590/91 Input Duty Cycle Lamp Current * 100% 50% 0% 100% 70% 33% * 100% DC is a logic HI at CMOS gate input. FIGURE 8. — PWM BRIGHTNESS CONTROL 6 Copyright © 1995 Rev. 0.9.3 3/96 PRODUCT DATABOOK 1996/1997 P AT E N T P E N D I N G LXM1590/LXM1591 C USTOMIZABLE CCFL IN V E RTER MODULES P R E L I M I N A R Y D S A T A H E E T COMPLETING THE MODULE PART NUMBER LXM159 Module Type = = - Half Bridge Drive (7.0V to 30V Battery Voltage) Full Bridge Drive (4.5V to 6.5V Battery Voltage) Nominal Input Voltage (4 thru 11 NiMH cells) = = = = 4.8 VDC 6.0 VDC 7.2 VDC 8.4 VDC 5 6 7 8 = = = = 9.6 VDC 10.8 VDC 12.0 VDC 13.2 VDC 9 0 = = 5 6 7 8 = = = = 8.1 VDC 9.0 VDC 9.9 VDC 10.8 VDC 9 0 = = RSVD * RSVD * 450 VRMS 500 VRMS 550 VRMS 600 VRMS 9 0 = = RSVD * RSVD * 900 VRMS 1000 VRMS 1100 VRMS 7 8 9 = = = 1200 VRMS 1300 VRMS 1400 VRMS = = RSVD * RSVD * = = = = 4.5 VDC 5.4 VDC 6.3 VDC 7.2 VDC M Minimum Input Voltage 1 2 3 4 X X X X R X - Z Z RSVD * RSVD * P 1 2 3 4 X L 0 1 X E 1. Choose either the half or full bridge version by comparing your operating conditions and efficiency needs to the efficiency curves in Figures 1 & 2. 2. Choose the nominal input voltage you will be using, that is, the voltage where you want efficiency to be highest. Selections are in 1.2V increments to match the 1.2V/cell potential of NiCd and NiMH batteries. If a different type of power source is being used, select the closest nominal voltage. 3. Choose the minimum input voltage where full lamp brightness is needed. For convenience, selections are in 0.9V increments, corresponding to end of discharge potential for NiCd and NiMH cells. Your selection need not correspond to the number of cells selected for nominal voltage input. 4. Specify lamp running voltage. 5. Specify maximum lamp start voltage. 6. Specify lamp running current. 7. Choose over temperature option. (See "Over Temperature Protection Option" Section on Page 3 for complete description of this option.) 8. Choose mechanical configuration (-zz) from the specific mechanical data sheets below. Nominal Lamp Operating Voltage 1 2 3 4 = = = = 250 VRMS 300 VRMS 350 VRMS 400 VRMS 5 6 7 8 = = = = 1 2 3 = = = 600 VRMS 700 VRMS 800 VRMS A Maximum Lamp Start Voltage 4 5 6 = = = Nominal Lamp Operating Current at Full Brightness = = = = 2 mARMS 3 mARMS 4 mARMS 5 mARMS S 1 2 3 4 5 6 7 8 = = = = 6 mARMS 7 mARMS 10 mARMS 12 mARMS 9 0 Reserved Mechanical Configuration See following Specific Data Sheets RSVD = Reserved for Special Requirements * Note: Other configurations are available. If you need a configuration not listed above please call us. Copyright © 1995 Rev. 0.9.3 3/96 7 PRODUCT DATABOOK 1996/1997 P AT E N T P E N D I N G LXM1590/LXM1591 C USTOMIZABLE CCFL IN V E RTER MODULES P R E L I M I N A R Y D A T A S H E E T PHYSICAL DIMENSIONS LXM1590-xxxxx-01 .44 (11.2) 4.03 (102.4) 3.450 (87.63) 1-1 2-1 .695 (17.65) .18 (4.6) .350 (8.89) 2-4 1-8 Connector CN-1 0.125 (3.18) Diameter Hole, 2 places No other holes on board. Connector CN-2 .315 Max. (8) .031 (0.8) All dimensions in inches (mm) CN-1 = MOLEX 53261-0890 CN-2 = JST SM02(8.0) B-BHS-TB Connector Pinouts CN1-1 CN1-2 CN1-3 CN1-4 8 = = = = VIN VIN VCC GND CN1-5 CN1-6 CN1-7 CN1-8 = = = = GND SLEEP BRITE V REF CN2-1 = LAMP HI CN2-2 = LAMP LO Copyright © 1995 Rev. 0.9.3 3/96 PRODUCT DATABOOK 1996/1997 P AT E N T P E N D I N G LXM1590/LXM1591 C USTOMIZABLE CCFL IN V E RTER MODULES P R E L I M I N A R Y D A T A S H E E T PHYSICAL DIMENSIONS LXM1591-xxxxx-01 .40 (10.16) 4.79 (121.6) 3.88 (98.55) 2-1 1-1 .72 (18.29) .160 (4.06) .400 (10.16) 2-2 1-8 0.125 (3.18) Diameter Hole, 2 places No other holes on board. Connector CN-1 Connector CN-2 .315 Max. (8) Warning!! High Voltage Present .031 (0.8) All dimensions in inches (mm) CN-1 = MOLEX 53261-0890 CN-2 = JST SM02(8.0) B-BHS-TB Connector Pinouts CN1-1 CN1-2 CN1-3 CN1-4 Copyright © 1995 Rev. 0.9.3 3/96 = = = = VIN VIN GND GND CN1-5 CN1-6 CN1-7 CN1-8 = = = = SLEEP BRITE AGND VREF CN2-1 = LAMP HI CN2-2 = LAMP LO 9