LTM8042/LTM8042-1 µModule Boost LED Driver and Current Source FEATURES DESCRIPTION n The LTM®8042 is a complete μModule® Boost LED Driver specifically designed to drive LEDs up to 1A, while the LTM8042-1 drives up to 350mA. It combines a boost power topology with a unique current loop to operate as a constant-current source. The PWM input provides as much as 3000:1 LED dimming, while 10:1 analog dimming can be accomplished by a single resistor or analog voltage applied to the CTL pin. As with any boost topology, the LTM8042/LTM8042-1 has an uninterrupted current path between its input and output and is thus intolerant to a short-circuit or overload from the output to ground. n n n n n n n n True Color PWM™ with 3000:1 Dimming Ratio Operates in Boost, Buck Mode or Buck-Boost Mode Wide Input Voltage Range: Operation from 3V to 30V Transient Protection to 40V Gate Driver for Optional PWM Dimming with P-channel MOSFET Adjustable Frequency: 250kHz to 2MHz Constant-Current and Constant-Voltage Regulation Low Shutdown Current: <1μA RoHS Compliant Package with Gold Pad Finish Tiny, Low Profile (9mm × 15mm × 2.82mm) Surface Mount LGA Package APPLICATIONS n n n n Display Backlighting Automotive and Avionic Lighting Illumination Scanners L, LT, LTC, LTM, Linear Technology, the Linear logo and μModule are registered trademarks and True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. # WHITE LEDS LED CURRENT 12VIN 6 1A LTM8042 24VIN 7 350mA LTM8042-1 8 1A LTM8042 9 350mA LTM8042-1 The LTM8042/LTM8042-1 is packaged in a thermally enhanced, compact overmolded land grid array (LGA) package. The LTM8042/LTM8042-1 is Pb-free and a RoHS compliant. TYPICAL APPLICATION μModule Boost LED Driver, Driving 8 White LEDs at 1A Efficiency vs VIN 97 UP TO 26.8V 96 VCC LTM8042 BSTIN/BKLED– PWM 95 LED+ RUN TG BSTOUT/BKIN 1A SYNC TGEN 4.7μF SS RT EFFICIENCY (%) VIN 16V TO 26V 94 93 92 91 90 89 GND CTL 33.2k fSW = 550kHz 88 4.7μF 87 16 17 18 19 20 21 22 23 24 25 26 VIN (V) 80421 TA01a 80421 TA01b 80421fa 1 LTM8042/LTM8042-1 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) VCC, RUN, PWM, TGEN, BSTIN/BKLED– ...................40V BSTOUT/BKIN, TG, LED+ ..........................................43V TG Pin Below LED+ ...................................................10V CTL, SYNC, SS............................................................6V RT ...............................................................................3V Internal Operating Temperature (Notes 3, 4) ........................................... –40°C to 125°C Solder Temperature .............................................. 245°C Storage Temperature ............................. –55°C to 125°C BSTIN/BKLED– TG 7 VCC BANK 2 BANK 3 BANK 4 BANK 5 6 LED+ BSTOUT/BKIN 5 4 BANK 1 TGEN 3 GND 2 CTL 1 A B C D E F G H RUN SYNC RT J K L SS PWM LGA PACKAGE 77-LEAD (15mm s 9mm s 2.82mm) TJMAX = 125°C, θJA = 15.7°C/W, θJCtop = 13.6°C/W, θJCbottom = 4.5°C/W, θJB = 9.4°C/W θ VALUES DETERMINED PER JESD 51-12 WEIGHT = 1.1g ORDER INFORMATION LEAD FREE FINISH TRAY PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTM8042EV#PBF LTM8042EV#PBF LTM8042V 77-Lead (15mm × 9mm × 2.82mm) LGA –40°C to 125°C LTM8042IV#PBF LTM8042IV#PBF LTM8042V 77-Lead (15mm × 9mm × 2.82mm) LGA –40°C to 125°C LTM8042EV-1#PBF LTM8042EV-1#PBF LTM8042-1V 77-Lead (15mm × 9mm × 2.82mm) LGA –40°C to 125°C LTM8042IV-1#PBF LTM8042IV-1#PBF LTM8042-1V 77-Lead (15mm × 9mm × 2.82mm) LGA –40°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ This product is only offered in trays. For more information go to: http://www.linear.com/packaging/ 80421fa 2 LTM8042/LTM8042-1 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full internal operating temperature range, otherwise specifications are at TA = 25°C. VCC = 5V, buck mode with 4Ω load. SYMBOL PARAMETER VCC(MIN) Minimum Input DC Voltage ILED LTM8042 LED Current CONDITIONS MIN l CTL Open CTL Open, RCTL = 6.81k LTM8042-1 LED Current RCTL = 6.81k TYP MAX 3 0.9 0.45 0.34 0.17 UNITS V 0.5 1.05 0.55 0.39 0.20 A A A A VCLAMP Open LED Clamp Voltage Boost Mode, LED+ Open 36 V ΔIOUT/IOUT Output Current Line Regulation LTM8042, 6V < BSTOUT/BKIN < 30V LTM8042-1, 6V < BSTOUT/BKIN < 30V 0.5 0.5 % % IQVCC VCC Supply Current PWM = 0V RUN = 0V 4.2 0.1 1 mA μA 0.22 0.68 1.7 0.25 0.8 2 0.27 0.92 2.3 MHz MHz MHz 6 9 12 μA 2.5 MHz fSW Switching Frequency RT = 90.9k RT = 22.1k RT = 6.04k ISS Soft-Start Pin Current SS = 0.5V, Out of Pin fSYNC Synchronization Frequency Range ISYNC SYNC Pull-Down Current (Into the Pin) VSYNC(IL) SYNC Input Low VSYNC(IH) SYNC Input High ICTL CTL Input Bias Current VRUN(IH) RUN Input Voltage High VRUN(IL) RUN Input Voltage Low IRUN RUN Pin Bias Current VPWM(IH) PWM Input Voltage High 0.3 VSYNC = 2V 60 μA 0.4 1.5 CTL = 0V, Flows Out of Pin V V 100 μA 1.5 V 60 0.4 V 100 μA 1.5 V VPWM(IL) PWM Input Voltage Low IPWM PWM Pin Bias Current VTG(OH) TG Output High Voltage Relative to LED+, 100k from LED+ to TG 0 V VTG(OL) TG Output Low Voltage Relative to LED+, 100k from LED+ to TG –7 V VTGEN(IH) TGEN Input Voltage High PWM = 0V VTGEN(IL) TGEN Input Voltage Low ITGEN TGEN Pin Bias Current 60 Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Absolute maximum voltage at VCC, RUN, PWM, TGEN, BSTIN/ BKLED– pins is 40V for non-repetitive one second transients and 30V for continuous operation. Note 3: The LTM8042E/LTM8042E-1 are guaranteed to meet performance specifications from 0°C to 125°C ambient. Specifications over the full –40°C to 125°C internal operating temperature range are assured by design, characterization and correlation with statistical process controls. 0.4 V 120 μA 1.5 V 100 0.4 V 200 μA The LTM8042I/LTM8042I-1 are guaranteed to meet specifications over the full –40°C to 125°C internal operating temperature range. Note that the maximum internal temperature is determined by specific operating conditions in conjunction with board layout, the rated package thermal resistance and other environmental factors. Note 4: This device includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed the maximum internal operating temperature when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability. 80421fa 3 LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTM8042 Efficiency vs VIN, Boost Operation, 6.8V at 1A LED String Efficiency vs VIN, Boost Operation, 10.1V at 1A LED String 90 Efficiency vs VIN, Boost Operation, 13.4V at 1A LED String 95 94 94 92 93 87 90 92 86 85 84 83 EFFICIENCY (%) 88 EFFICIENCY (%) EFFICIENCY (%) 89 88 86 91 90 89 88 84 87 82 82 81 86 80 80 5 VIN (V) 4 85 7 6 5 6 8 9 10 7 VIN (V) 80421 G02 80421 G01 Efficiency vs VIN, Boost Operation, 16.7V at 1A LED String 8 9 10 VIN (V) 11 12 13 80421 G03 Efficiency vs VIN, Boost Operation, 20.1V at 1A LED String Efficiency vs VIN, Boost Operation, 23.4V at 1A LED String 97 97 95 95 93 93 90 EFFICIENCY (%) EFFICIENCY (%) 92 88 86 EFFICIENCY (%) 94 91 89 91 89 84 87 87 82 85 85 83 80 8 9 10 11 12 13 VIN (V) 14 15 83 11 16 12 13 14 15 16 VIN (V) 17 18 19 12 13 14 15 16 17 18 19 20 21 22 VIN (V) 80421 G05 80421 G04 80421 G06 Efficiency vs VIN, Buck Mode, 3.5V at 1A LED String Efficiency vs VIN, Boost Operation, 26.8V at 1A LED String Efficiency vs VIN, Buck Mode, 6.8V at 1A LED String 97 94 EFFICIENCY (%) EFFICIENCY (%) 95 93 92 91 90 89 94 87 92 85 90 EFFICIENCY (%) 96 83 81 88 86 79 84 77 82 89 88 87 75 16 17 18 19 20 21 22 23 24 25 26 VIN (V) 80421 G07 80 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 VIN (V) 80421 G08 8 10 12 14 16 18 20 22 24 26 28 30 32 34 VIN (V) 80421 G09 80421fa 4 LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTM8042 Efficiency vs VIN, Buck Mode, 13.4V at 1A LED String Efficiency vs VIN, Buck Mode, 16.7V at 1A LED String 97 97 94 96 96 93 95 95 92 94 94 91 90 89 88 EFFICIENCY (%) 95 EFFICIENCY (%) EFFICIENCY (%) Efficiency vs VIN, Buck Mode, 10.1V at 1A LED String 93 92 91 92 91 90 90 87 89 89 86 88 88 85 87 12 14 16 18 20 22 24 26 28 30 32 34 VIN (V) 87 15 17 19 21 23 25 27 29 31 33 VIN (V) 80421 G10 19 21 23 25 27 VIN (V) 80421 G11 Efficiency vs VIN, Buck-Boost Mode, 3.6V at 1A LED String 29 31 33 80421 G12 Efficiency vs VIN, Buck-Boost Mode, 6.8V at 1A LED String Efficiency vs VIN, Buck-Boost Mode, 10.1V at 1A LED String 90 85 87 86 80 85 70 65 85 EFFICIENCY (%) EFFICIENCY (%) 75 80 84 83 82 75 60 81 70 55 80 8 4 6 8 10 12 14 16 18 20 22 24 26 28 30 VIN (V) 10 12 14 16 18 20 22 24 26 VIN (V) 12 13 14 15 16 17 18 19 20 21 22 23 24 VIN (V) 80421 G14 80421 G13 80421 G15 Maximum LED Current vs Input Voltage, Boost Operation Efficiency vs VIN, Buck-Boost Mode, 13.4V at 1A LED String 90 1200 MAXIMUM LED CURRENT (mA) 89 88 EFFICIENCY (%) EFFICIENCY (%) 93 87 86 85 84 83 82 1000 800 600 7.4V AT 1A 10.9V AT 1A 14.5V AT 1A 18.1V AT 1A 21.4V AT 1A 24.8V AT 1A 28.2V AT 1A 400 200 81 80 0 15 16 17 18 VIN (V) 19 20 80421 G16 0 5 10 15 20 INPUT VOLTAGE (V) 25 30 80421 G17 80421fa 5 LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTM8042 Maximum LED Current vs VIN, Buck Mode Maximum LED Current vs Input Voltage, Buck-Boost Mode 1000 1200 MAXIMUM LED CURRENT (mA) 900 LED CURRENT (mA) 800 700 600 500 400 3.8V AT 1A 7.4V AT 1A 10.9V AT 1A 14.5V AT 1A 18.1V AT 1A 21.4V AT 1A 24.8V AT 1A 300 200 100 0 0 5 10 15 VIN (N) 20 25 1000 800 600 7.4V AT 1A 10.9V AT 1A 14.5V AT 1A 18.1V AT 1A 21.4V AT 1A 24.8V AT 1A 28.2V AT 1A 400 200 0 30 0 10 20 30 INPUT VOLTAGE (V) 80421 G18 80421 G19 Junction Temperature Rise vs Load, Boost Operation, 8.3V at 1A LED String Quiescent Current vs Input Voltage, Open LED LED Current vs CTL Voltage 40 25 35 80 60 40 20 20 30 TEMPERATURE (°C) QUIESCENT CURRENT (mA) LED CURRENT SCALING (%) 100 40 25 20 15 5VIN 15 10 10 5 5 0 0 0 200 400 600 800 1000 ADJUST VOLTAGE (mV) 1200 0 0 5 10 15 20 INPUT VOLTAGE (V) 25 80421 G20 30 0 400 600 LED CURRENT (mA) 800 80421 G21 Junction Temperature Rise vs Load, Boost Operation, 10.9V at 1A LED String 1000 80421 G22 Junction Temperature Rise vs Load, Boost Operation, 13.6V at 1A LED String 20 Junction Temperature Rise vs Load, Boost Operation, 18.1V at 1A LED String 35 25 18 30 16 20 7VIN 12 10 8 6 4 8VIN TEMPERATURE (°C) 14 TEMPERATURE (°C) TEMPERATURE (°C) 200 15 10 25 9VIN 20 15 10 5 5 2 0 0 0 0 200 400 600 LED CURRENT (mA) 800 1000 80421 G23 0 200 400 600 LED CURRENT (mA) 800 1000 80421 G24 0 200 400 600 LED CURRENT (mA) 800 1000 80421 G25 80421fa 6 LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTM8042 Junction Temperature Rise vs Load, Buck Mode, 3.8V at 1A LED String 18 18 16 16 12 25 20 14 24VIN TEMPERATURE (°C) 10 8 12VIN 6 12 10 8 12VIN 6 4 4 2 2 0 24VIN 200 400 600 LED CURRENT (mA) 800 1000 0 200 400 600 LED CURRENT (mA) 800 80421 G26 0 20 24VIN 15 10 800 1000 10 0 0 200 400 600 LED CURRENT (mA) 800 80421 G29 0 1000 TEMPERATURE (°C) 5VIN 800 1000 80421 G31 40 35 25 20 15 400 600 LED CURRENT (mA) Junction Temperature Rise vs Load, Buck-Boost Mode, 8.3V at 1A LED String 30 25 24VIN 200 80421 G30 Junction Temperature Rise vs Load, Buck-Boost Mode, 3.8V at 1A LED String Junction Temperature Rise vs Load, Buck-Boost Mode, 2.9V at 1A LED String 10 24VIN 15 5 0 400 600 LED CURRENT (mA) 1000 20 5 200 800 25 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 5 0 400 600 LED CURRENT (mA) Junction Temperature Rise vs Load, Buck Mode, 18.1V at 1A LED String 25 10 200 80421 G28 30 20 TEMPERATURE (°C) 0 1000 Junction Temperature Rise vs Load, Buck Mode, 13.6V at 1A LED String 25 24VIN 12VIN 80421 G27 Junction Temperature Rise vs Load, Buck Mode, 10.9V at 1A LED String 15 10 0 0 0 24VIN 15 5 5VIN 30 20 24VIN 15 12VIN 10 TEMPERATURE (°C) TEMPERATURE (°C) 14 Junction Temperature Rise vs Load, Buck Mode, 8.3V at 1A LED String TEMPERATURE (°C) Junction Temperature Rise vs Load, Buck Mode, 2.9V at 1A LED String 12VIN 25 20 15 10 5 5 12VIN 5 0 0 0 0 200 400 600 LED CURRENT (mA) 800 1000 80421 G32 0 200 400 600 LED CURRENT (mA) 800 1000 80421 G33 0 200 400 600 LED CURRENT (mA) 800 1000 80421 G34 80421fa 7 LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTM8042 Junction Temperature Rise vs Load, Buck-Boost Mode, 10.9V at 1A LED String Junction Temperature Rise vs Load, Buck-Boost Mode, 13.6V at 1A LED String 50 Junction Temperature Rise vs Load, Buck-Boost Mode, 15.5V at 350mA LED String 60 25 45 50 12VIN 30 25 20 15 10 20 40 12VIN 16VIN 30 20 TEMPERATURE (°C) TEMPERATURE (°C) 35 TEMPERATURE (°C) 40 12VIN 15 10 5 10 5 0 0 0 200 400 600 LED CURRENT (mA) 800 1000 0 0 200 400 600 LED CURRENT (mA) 80421 G35 800 1000 0 50 100 150 200 250 LED CURRENT (mA) 80421 G36 300 350 80421 G37 LTM8042/LTM8042-1 RUN Pin Current vs Voltage 160 140 RUN CURRENT (μA) 120 100 80 60 40 20 0 10 0 20 30 RUN VOLTAGE (V) 80421 G38 LTM8042-1 Efficiency vs VIN, Boost Operation, 6.7V at 350mA LED String Efficiency vs VIN, Boost Operation, 9.7V at 350mA LED String Efficiency vs VIN, Boost Operation, 12.6V at 350mA LED String 95 95 90 90 90 85 85 85 80 75 EFFICIENCY (%) 95 EFFICIENCY (%) EFFICIENCY (%) 40 80 75 70 70 2 3 4 VIN (V) 5 6 65 2.5 4.5 6.5 8.5 VIN (V) 80421 G39 75 70 65 65 80 80421 G40 3 5 7 VIN (V) 9 11 80421 G41 80421fa 8 LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTM8042-1 Efficiency vs VIN, Boost Operation, 18.6V at 350mA LED String 95 90 90 90 85 85 85 80 75 EFFICIENCY (%) 95 70 80 75 5 6 7 8 9 10 11 12 13 14 15 VIN (V) 75 65 65 4 80 70 70 65 5 6 7 8 9 10 11 12 13 14 15 16 17 18 VIN (V) 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 VIN (V) 80421 G42 80421 G44 80421 G43 Efficiency vs VIN, Boost Operation, 24.8V at 350mA LED String Efficiency vs VIN, Buck Mode, 3.7V at 350mA LED String Efficiency vs VIN, Buck Mode, 6.7V at 350mA LED String 93 96 91 91 94 89 89 87 87 85 83 81 92 EFFICIENCY (%) EFFICIENCY (%) 93 EFFICIENCY (%) Efficiency vs VIN, Boost Operation, 21.6V at 350mA LED String 95 EFFICIENCY (%) EFFICIENCY (%) Efficiency vs VIN, Boost Operation, 15.6V at 350mA LED String 85 83 81 90 88 86 79 79 84 77 77 82 75 75 6 8 10 12 14 16 VIN (V) 18 20 22 80 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 VIN (V) 24 8 10 12 14 16 18 20 22 24 26 28 30 32 34 VIN (V) 80421 G46 80421 G45 Efficiency vs VIN, Buck Mode, 9.7V at 350mA LED String 80421 G47 Efficiency vs VIN, Buck Mode, 12.6V at 350mA LED String 98 Efficiency vs VIN, Buck Mode, 15.6V at 350mA LED String 97 97 95 95 93 93 96 90 88 86 EFFICIENCY (%) 92 EFFICIENCY (%) EFFICIENCY (%) 94 91 89 91 89 84 87 87 82 85 80 11 13 15 17 19 21 23 25 27 29 31 33 VIN (V) 80421 G48 85 14 16 18 20 22 24 VIN (V) 26 28 30 32 80421 G49 17 19 21 23 25 27 VIN (V) 29 31 33 80421 G50 80421fa 9 LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTM8042-1 Efficiency vs VIN, Buck Mode, 18.6V at 350mA LED String Efficiency vs VIN, Buck-Boost Mode, 3.7V at 350mA LED String 97 Efficiency vs VIN, Buck-Boost Mode, 6.7V at 350mA LED String 90 90 80 85 70 80 91 89 60 EFFICIENCY (%) 93 EFFICIENCY (%) EFFICIENCY (%) 95 50 40 30 23 25 27 29 VIN (V) 31 45 0 40 33 10 0 20 VIN (V) 30 0 40 5 10 15 VIN (V) 20 Efficiency vs VIN, Buck-Boost Mode, 12.6V at 350mA LED String 90 25 30 80421 G53 80421 G52 Efficiency vs VIN, Buck-Boost Mode, 9.7V at 350mA LED String Efficiency vs VIN, Buck-Boost Mode, 15.6V at 350mA LED String 88 90 86 85 85 84 75 70 65 80 EFFICIENCY (%) EFFICIENCY (%) 80 EFFICIENCY (%) 60 10 80421 G51 75 70 60 82 80 78 76 74 65 55 72 50 70 60 5 10 15 VIN (V) 20 25 30 0 5 10 15 VIN (V) 20 Maximum LED Current vs Input Voltage, Boost Operation 87 MAXIMUM LED CURRENT (mA) 81 79 77 400 350 350 300 250 200 150 6.3V AT 350mA 15.5V AT 350mA 18.6V AT 350mA 21.7V AT 350mA 24.8V AT 350mA 50 75 Maximum LED Current vs Input Voltage, Buck Mode 400 100 7 9 11 13 15 VIN (V) 80421 G57 300 250 200 150 3.2V AT 350mA 6.3V AT 350mA 9.4V AT 350mA 12.4V AT 350mA 15.5V AT 350mA 18.6V AT 350mA 100 50 0 5 0 0 5 10 15 INPUT VOLTAGE (V) 20 80421 G56 80421 G55 Efficiency vs VIN, Buck-Boost Mode, 18.6V at 350mA LED String 83 15 VIN (V) 80421 G54 85 10 0 25 MAXIMUM LED CURRENT (mA) 0 EFFICIENCY (%) 65 50 87 21 70 55 20 85 75 20 25 80421 G58 0 10 20 30 INPUT VOLTAGE (V) 40 80421 G59 80421fa 10 LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTM8042-1 Maximum LED Current vs Input Voltage, Buck-Boost Mode 400 120 300 250 200 150 3.2V AT 350mA 6.3V AT 350mA 9.4V AT 350mA 12.4V AT 350mA 15.5V AT 350mA 18.6V AT 350mA 100 50 0 10 0 80 70 100 QUIESCENT CURRENT (mA) LED CURRENT SCALING (%) 350 MAXIMUM LED CURRENT (mA) Quiescent Current vs Input Voltage, Open LED LED Current vs CTL Voltage 80 60 40 20 40 200 400 600 800 CTL VOLTAGE (mV) 1000 80421 G60 0 5VIN 2 0 7 8 6 7 5VIN 4 3 2 5VIN 5 4 3 2 1 0 0 0 50 100 150 200 250 LED CURRENT (mA) 80421 G63 300 0 350 50 100 150 200 250 LED CURRENT (mA) Junction Temperature Rise vs Load, Buck Mode, 2.3V at 350mA LED String 350 Junction Temperature Rise vs Load, Buck Mode, 3.2V at 350mA LED String 10 14 300 80421 G65 80421 G64 Junction Temperature Rise vs Load, Boost Operation, 15.5V at 350mA LED String 35 6 5 350 30 80421 G62 1 300 10 15 20 25 INPUT VOLTAGE (V) Junction Temperature Rise vs Load, Boost Operation, 11.2V at 350mA LED String TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 3 5 80421 G61 1 6 9 8 TEMPERATURE (°C) 10 5VIN 8 6 4 5 24VIN 7 TEMPERATURE (°C) 12 TEMPERATURE (°C) 20 1200 4 100 150 200 250 LED CURRENT (mA) 30 Junction Temperature Rise vs Load, Boost Operation, 9.4V at 350mA LED String 5 50 40 0 0 Junction Temperature Rise vs Load, Boost Operation, 6.8V at 350mA LED String 0 50 10 0 20 30 INPUT VOLTAGE (V) 60 6 5 12VIN 4 3 2 2 4 12VIN 3 2 5VIN 1 1 0 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350 80421 G66 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350 80421 G67 0 50 100 150 200 250 LED CURRENT (mA) 300 350 80421 G68 80421fa 11 LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTM8042-1 Junction Temperature Rise vs Load, Buck Mode, 9.4V at 350mA LED String Junction Temperature Rise vs Load, Buck Mode, 6.8V at 350mA LED String 10 TEMPERATURE (°C) TEMPERATURE (°C) 24VIN 8 6 12VIN 4 14 14 12 12 10 TEMPERATURE (°C) 12 Junction Temperature Rise vs Load, Buck Mode, 11.2V at 350mA LED String 24VIN 8 6 4 2 50 100 150 200 250 LED CURRENT (mA) 300 0 350 50 100 150 200 250 LED CURRENT (mA) 300 0 350 24VIN 6 4 24VIN 12VIN 6 4 2 5VIN 2 300 350 0 50 12VIN 6 4 5VIN 3.3VIN 0 100 150 200 250 LED CURRENT (mA) 300 350 0 50 100 150 200 250 LED CURRENT (mA) 80421 G73 80421 G72 300 350 80421 G74 Junction Temperature Rise vs Load, Buck-Boost Mode, 9.4V at 350mA LED String Junction Temperature Rise vs Load, Buck-Boost Mode, 6.8V at 350mA LED String 16 12 14 10 12 12VIN TEMPERATURE (°C) TEMPERATURE (°C) 8 2 3.3VIN 0 0 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 8 350 10 8 24VIN 300 12 12 100 150 200 250 LED CURRENT (mA) 100 150 200 250 LED CURRENT (mA) Junction Temperature Rise vs Load, Buck-Boost Mode, 3.2V at 350mA LED String 10 50 50 80421 G71 Junction Temperature Rise vs Load, Buck-Boost Mode, 2.3V at 350mA LED String 14 0 4 80421 G70 80421 G69 Junction Temperature Rise vs Load, Buck Mode, 15.5V at 350mA LED String 10 6 0 0 0 24VIN 8 2 2 0 10 8 6 5VIN 4 10 12VIN 8 5VIN 6 4 2 2 0 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350 80421 G75 0 50 100 150 200 250 LED CURRENT (mA) 300 350 80421 G76 80421fa 12 LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTM8042-1 Junction Temperature Rise vs Load, Buck-Boost Mode, 11.2V at 350mA LED String Junction Temperature Rise vs Load, Buck-Boost Mode, 15.5V at 350mA LED String 30 18 16 25 TEMPERATURE (°C) TEMPERATURE (°C) 14 12 12VIN 10 8 5VIN 6 20 15 12VIN 10 5VIN 4 5 2 0 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350 80421 G77 0 50 100 150 200 250 LED CURRENT (mA) 300 350 80421 G78 PIN FUNCTIONS GND (Bank 1): Signal and Power Return. Tie these pads to a local ground plane below the LTM8042/LTM8042-1 and the circuit components. In most applications, the bulk of the heat flow out of the LTM8042/LTM8042-1 is through these pads, so the printed circuit design has a large impact on the thermal performance of the part. See the PCB Layout and Thermal Considerations sections for more details. VCC (Bank 2): Internal Housekeeping Power for the LTM8042/LTM8042-1. Connect to an external power source between 3V and 30V. The LTM8042/LTM8042-1 can withstand transients of 40V. BSTIN/BKLED– (Bank 3): Power Input for Boost Operation, as Well as the Cathode Connection for the LED String in Buck Mode. If the LTM8042/LTM8042-1 is used in boost mode, these pins must be locally decoupled. BSTOUT/BKIN (Bank 4): Output of the Boost Converter, as Well as the Input for Buck Mode. If the LTM8042/ LTM8042-1 is used in buck mode, these pins must be locally decoupled. LED+ (Bank 5): Connect this to the anode of the LED string. This can also be connected to the PWM dimming MOSFET if used. RUN (Pin F1): Module Enable. Tie to 1.5V or higher to enable the LTM8042/LTM8042-1 or 0.4V or less to disable device. SYNC (Pin G1): Frequency Synchronization Pin. Tie an external clock signal here. The RT resistor should be chosen to program a switching frequency that is 20% slower than SYNC pulse frequency. Tie the SYNC pin to GND if this feature is not used. RT (Pin H1): Timing Resistor Pin. Used to program the switching frequency of the LTM8042/LTM8042-1 by connecting a resistor from this pin to GND. The Applications Information section of the data sheet includes a table to determine the resistance value based on the desired switching frequency. Minimize capacitance at this pin. SS (Pin J1): Soft-Start Pin. Place a soft-start capacitor here. Leave the pin open if not used. 80421fa 13 LTM8042/LTM8042-1 PIN FUNCTIONS TG (Pin J7): Top Gate Driver Output. In response to an active high PWM signal, this pin will drive the gate of an external series P-channel MOSFET device low. An internal 7V clamp protects the PFET gate. This pin can also be used to disconnect the load when RUN is pulled low. Leave TG unconnected if not used. PWM (Pin K1): Pulse Width Modulation Input Pin. A low signal turns off the LED string, disables the main switch and pulls the TG pin high. Drive above 1.55V to deliver current to the output. Tie the PWM pin to the RUN pin if not used. There is an equivalent 50k resistor from PWM pin to ground internally. CTL (Pin L2): LED Current Adjustment Pin. Apply a voltage between approximately 1V and 0V to modulate the LED+ output current, or tie a resistor to GND to modulate the LED+ current. CTL is internally tied to a 2V precision reference via a 20k 1% resistor. Leave floating if unused. TGEN (Pin L3): Top Gate (TG) Enable Input Pin. Tie to 1.5V or higher to enable the P-channel MOSFET driver function. Tie the TGEN pin to ground if the TG function is not used. There is an internal 40k resistor from TGEN to GND. BLOCK DIAGRAM BSTOUT/BKIN 4.7μH BSTIN/BKLED– 0.1μF 1M 0.1μF RSNS 0.10Ω (LTM8042) 0.27Ω (LTM8042-1) VCC OPEN LED PROTECTION (1V THRESHOLD) 0.1μF CURRENT MODE LED CONTROLLER RUN SS 28.0k CURRENT SENSE+ CURRENT SENSE– TG PWM SYNC LED+ 2V 20.0k 1% 50k GND RT TGEN CTL 80421 BD 80421fa 14 LTM8042/LTM8042-1 OPERATION The LTM8042/LTM8042-1 is a complete, full featured, current mode regulator specifically designed to drive light emitting diodes (LEDs) or other loads where a constant current up to 1A (350mA for the LTM8042-1) is required. The LTM8042/LTM8042-1 can operate in any of three LED drive topologies: boost, buck mode and buck-boost mode. The device features both analog and PWM dimming, a PWM P-channel MOSFET driver, and a suite of control functions: RUN control, soft-start, user programmable switching frequency, and external frequency synchronization. Operation can be best understood by referring to the Block Diagram. The power stage is a boost converter that regulates the output current by reading the voltage across a power sense resistor that is in series with the output. As with any boost topology, there is an uninterrupted current path between the input and output terminals. Current between these two terminals is not limited, so the device is intolerant to a short-circuit or overload from any of the output terminals (LED+, BSTOUT/BKIN) to GND. There are two ways to dim a LED with the LTM8042/ LTM8042-1. One way is to adjust the current on the LED array by setting the analog voltage on the CTL pin. The CTL pin is internally pulled up to a precision 2V reference through a 1% 20k resistor. Leaving the CTL pin floating sets the LED pin current to 1A. Reducing the voltage below 1.1V on the CTL pin proportionally reduces the current flowing out of LED+. This can be accomplished by connecting a resistor from the CTL pin to GND, forming a divider network with the internal 20k resistor, or by driving the CTL pin directly to a voltage source, such as a DAC. The other way the LTM8042/LTM8042-1 can dim a LED array is by pulse width modulation using the PWM pin and an optional external P-channel MOSFET. The external P-channel MOSFET can be conveniently operated by the integrated gate driver at pin TG. The gate drive function can be enabled or disabled by the TGEN pin. If the PWM pin is pulled high, the part operates normally. If the PWM pin is unconnected or pulled low, the LTM8042/LTM8042-1 stops switching and the internal control circuitry is held in its present state. This way, the LTM8042/LTM8042-1 “remembers” the current sourced from the LED+ output until PWM is pulled high again. This leads to a highly linear relationship between pulse width and output light, allowing for a large and accurate dimming range. The RUN pin is used to deactivate the LTM8042/LTM8042-1. When the RUN pin is pulled to a logic low state, the device is shut down and draws typically less than 1μA of current. The SS pin is used to limit inrush current during start-up. The LTM8042/LTM8042-1 integrates a current source with this function, so only a capacitor is necessary to establish the soft-start characteristics of the output current. The switching frequency is set by applying a single resistor from the RT pin to GND, allowing operation anywhere from 250kHz to 2MHz, and the SYNC pin allows synchronization to an external source between 300kHz and 2.5MHz. 80421fa 15 LTM8042/LTM8042-1 APPLICATIONS INFORMATION For most applications, the design process is straight forward, summarized as follows: 1. Decide whether the LTM8042/LTM8042-1 should operate in boost, buck, or buck-boost mode. 2. Look at Tables 1 through 6 and find the line that best matches the input and output conditions of the system under consideration. 3. Connect CIN, COUT, CVCC and RT as indicated in the appropriate table. 4. Connect the remaining pins as needed by the system requirements. While these component combinations have been tested for proper operation, it is incumbent upon the user to verify proper operation over the intended system’s line, load and environmental conditions. If the desired LED current is not listed in Tables 1 through 6, set it by applying the proper voltage the CTL pin. Graphs of the LTM8042/LTM8042-1 LED current scaling vs CTL voltage are given in the Typical Performance Characteristics section. If a voltage source is not available to drive the CTL pin, a resistor may be applied from the CTL pin to GND. The CTL pin is internally pulled up to a 2V reference voltage through a 20k resistor (please see the Block Diagram for details). Open LED Protection The LTM8042/LTM8042-1 has internal open LED circuit protection. If the LED is absent or fails open, the LTM8042/LTM8042-1 clamps the voltage on the LED+ and BSTOUT/BKIN pin to protect the output against overvoltage. The internal boost switching converter then regulates its output to 36V. In buck mode, the full open LED voltage is stood off by the internal power Schottky diode. At high operating temperatures, the power Schottky reverse leakage current will rise. This increases the power dissipation within the diode, which raises the junction temperature. This temperature rise can be large, so care needs to be taken at high operating temperatures. Setting the Switching Frequency The LTM8042/LTM8042-1 uses a constant frequency architecture that can be programmed over a 250kHz to 2MHz range with a single external timing resistor from the RT pin to ground. Table 7 shows suggested RT selections for a variety of switching frequencies. Table 7. Switching Frequency vs RT SWITCHING FREQUENCY (kHz) RT (kΩ) 250 86.6 500 37.4 800 21.0 1000 15.8 1500 9.09 2000 6.04 The other way to set the operating frequency of the LTM8042/LTM8042-1 is to drive the SYNC pin with an external signal. For proper operation, a resistor should be connected at the RT pin and be able to generate a switching frequency 20% lower than the external clock when the external clock is absent. In general, a lower switching frequency should be used where either very high or very low switching duty cycle operation is required, or high efficiency is desired. Selection of a higher switching frequency will allow use of smaller value external components and yield a smaller solution size and profile. Operating Modes The LTM8042/LTM8042-1 employs a ground referred power switch to implement a boost power switching circuit. As such, it can be used to implement the three most popular LED driving topologies: boost, buck mode, and buck-boost mode. Example layouts of each operating mode are given in Figures 2 through 4 and schematics are shown in the Typical Applications section. 80421fa 16 LTM8042/LTM8042-1 APPLICATIONS INFORMATION Which mode to use depends upon the operating conditions. Boost is generally selected when the voltage across the LED string is always higher than the input voltage. Buck mode is the dual of boost, used when the voltage across the LED string is always lower than VIN. Finally, buck-boost mode is used when the VIN can vary both above and below the voltage across the LED string. The land grid array of the LTM8042/LTM8042-1 is designed to conveniently accommodate all three operating modes. Please refer to the PCB Layout section for suggested examples of how to lay out each operating mode. PWMRATIO = Dimming Control There are two methods to control the current source for dimming using the LTM8042/LTM8042-1. One method uses the PWM pin to modulate the current source between zero and full current to achieve a precisely programmed average current. To make this method of current control more accurate, the switch demand current is internally stored during the quiescent phase (PWM low). This feature minimizes recovery time when the PWM signal returns high. When using PWM dimming, use a P-channel MOSFET disconnect switch in the LED current path (see Figure 1) to prevent the output capacitor from discharging during the PWM off-time. Enable this function by pulling TGEN above 1.5V. LTM8042 VIN The minimum PWM on or off-time will depend on the choice of operating frequency through the RT input pin or the SYNC pin. When using the SYNC function, the SYNC and PWM signals must have the rising edges aligned to achieve the optimized high PWM dimming ratio. For best current accuracy, the minimum PWM low or high time should be at least six switching cycles (3μs for ƒSW = 2MHz). The maximum PWM period is determined by the system. The maximum PWM dimming ratio (PWMRATIO) can be calculated from the maximum PWM period (TMAX) and the minimum PWM pulse width (TMIN) as follows: VCC BSTIN/BKLED– TGEN (1) A set of values that give a 3000:1 dimming ratio, for example, would be a switching frequency of ƒSW = 2MHz, TMAX = 9ms and TMIN = 3μs. Equation (1) becomes: PWMRATIO = 9ms/3μs = 3000:1 The second method of dimming control uses the CTL pin to linearly adjust the current sense threshold during the PWM high state. When the CTL pin voltage is less than 1V, the LED current is: ILED = VCTL When VCTL is higher than 1.1V, the LED current is clamped to 1A. The LED current programming feature can be used in conjunction with the PWM to possibly increase the total dimming range by an additional factor of ten. LED+ RUN TMAX TMIN TG BSTOUT/BKIN PWM SYNC SS RT GND CTL 80421 TA01a Figure 1. The LTM8042/LTM8042-1 Can Control a P-Channel PWM Switch 80421fa 17 LTM8042/LTM8042-1 APPLICATIONS INFORMATION PCB Layout Most of the headaches associated with PCB layout have been alleviated or even eliminated by the high level of integration of the LTM8042/LTM8042-1. The device is nevertheless a switching power supply, and care must be taken to minimize EMI and ensure proper operation. Even with the high level of integration, you may fail to achieve specified operation with a haphazard or poor layout. See Figures 2, 3 and 4 for suggested layouts of boost, buck and buck-boost operating modes. 4. Place the CIN, CVCC and COUT capacitors such that their ground current flows directly adjacent to or underneath the LTM8042/LTM8042-1. 5. Connect all of the GND connections to as large a copper pour or plane area as possible on the top layer. Avoid breaking the ground connection between the external components and the LTM8042/LTM8042-1. Use vias to connect the GND copper area to the board’s internal ground planes. Liberally distribute these GND vias to provide both a good ground connection and thermal path to the internal planes of the printed circuit board. Pay attention to the location and density of the thermal vias in Figures 2 through 4. The LTM8042/LTM8042-1 can benefit from the heat sinking afforded by vias that connect to internal GND planes at these locations, due to their proximity to internal power handling components. The optimum number of thermal vias depends upon the printed circuit board design. For example, a board might use very small via holes. It should employ more thermal vias than a board that uses larger holes. Ensure that the grounding and heat sinking are acceptable. A few rules to keep in mind are: 1. Place the RT resistor as close as possible to its respective pins. 2. Place the CIN and CVCC capacitor as close as possible to the VIN and GND connections of the LTM8042/ LTM8042-1. 3. Place the COUT capacitor as close as possible to the BSTOUT/BKIN or BSTIN/BKLED– and GND connection of the LTM8042/LTM8042-1. TO LED STRING GND CIN VIN COUT LED+ BSTIN/BKLED– TG LED+ VCC BSTOUT/BKIN CVCC GND TGEN CTL PWM SS SYNC RUN GND 80421 F02 RT THERMAL VIAS TO GROUND PLANE Figure 2. Suggested Layout for Boost Operation 80421fa 18 LTM8042/LTM8042-1 APPLICATIONS INFORMATION TO LED STRING COUT VIN CVCC VIN LED+ CIN BSTIN/BKLED– TG LED+ VCC BSTOUT/BKIN GND TGEN CTL 80421 F03 PWM SS SYNC RUN GND RT THERMAL VIAS TO GROUND PLANE Figure 3. Suggested Layout for Buck Mode TO LED STRING TO LED STRING COUT2 COUT1 LED+ CIN VIN BSTIN/BKLED– TG LED+ VCC BSTOUT/BKIN CVCC TGEN CTL PWM SS SYNC RUN GND 80421 F04 RT THERMAL VIAS TO GROUND PLANE Figure 4. Suggested Layout for Buck-Boost Mode 80421fa 19 LTM8042/LTM8042-1 APPLICATIONS INFORMATION Table 1. LTM8042 Recommended Values and Configuration for Boost (TA = 25°C) VIN RANGE (BSTIN/ BKLED–) 3V to 3.6V 3V to 5.1V 3V to 6.3V 3V to 9.3V 3V to 10V 3V to 12.6V 3.7V to 15V 3V to 3.85V 3V to 5.6V 3V to 7V 3V to 10.2V 4V to 12.6V 4V to 14.5V 6.3V to 18.7V 3V to 3.8V 3V to 5.5V 3.3V to 7V 4.1V to 10V 5.5V to 12.5V 6.4V to 15V 9V to 20.8V 3V to 3.8V 3.3V to 5.7V 4V to 7.2V 5.2V to 10.4V 7V to 13V 8.2V to 15.5V 11.8V to 21.2V 3.3V to 3.5V 4V to 5.8V 5V to 7.6V 7V to 11V 9.5V to 13.5V 11V to 16V 16.5V to 21V 5V to 5.8V 6.4V to 7.7V 8.6V to 11.3V 11.3V to 13.8V 13.4V to 16.5V 20.5V to 22.5V VCC Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– Connect to BSTIN/BKLED– CIN (BSTIN/BKLED– TO GND) 1μF 0805 X7R 10V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 1μF 0805 X7R 16V 1μF 0805 X7R 16V 4.7μF 1206 X7R 10V 4.7μF 1206 X7R 10V 4.7μF 1206 X7R 10V 4.7μF 1206 X7R 16V 4.7μF 1206 X7R 16V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 25V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 1μF 1206 X7R 16V 1μF 1206 X7R 16V 2.2μF 1206 X7R 25V 1μF 1206 X7R 10V 1μF 1206 X7R 10V 1μF 1206 X7R 10V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 25V 1μF 1206 X7R 10V4 1μF 1206 X7R 10V 1μF 1206 X7R 10V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 25V 1μF 1206 X7R 10V 1μF 1206 X7R 10V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 16V 4.7μF 1206 X7R 25V 4.7μF 1206 X7R 25V COUT (BSTOUT/BKIN TO GND) 1μF 0805 X7R 10V 1μF 0805 X7R 10V 1μF 0805 X7R 16V 1μF 0805 X7R 16V 1μF 0805 X7R 25V 1μF 0805 X7R 25V 1μF 0805 X7R 50V 2.2μF 1206 X7R 10V 2.2μF 1206 X7R 10V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 25V 2.2μF 1206 X7R 25V 2.2μF 1206 X7R 50V 2.2μF 1206 X7R 10V 2.2μF 1206 X7R 10V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 25V 2.2μF 1206 X7R 25V 2.2μF 1206 X7R 50V 2.2μF 1206 X7R 10V 2.2μF 1206 X7R 10V 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 16V 4.7μF 1206 X7R 25V 4.7μF 1206 X7R 25V 4.7μF 1206 X7R 50V 4.7μF 1206 X7R 10V 4.7μF 1206 X7R 10V 4.7μF 1206 X7R 16V 4.7μF 1206 X7R 16V 4.7μF 1206 X7R 25V 4.7μF 1206 X7R 25V 4.7μF 1206 X7R 50V 4.7μF 1206 X7R 10V 4.7μF 1206 X7R 16V 4.7μF 1206 X7R 16V 4.7μF 1206 X7R 25V 4.7μF 1206 X7R 25V 4.7μF 1206 X7R 50V LED STRING VOLTAGE LED (LED+ TO STRING GND) CURRENT RCTL 4V to 6V 35mA 523 6V to 9V 35mA 523 8V to 12V 35mA 523 12V to 16V 35mA 523 15V to 21V 35mA 523 18V to 24V 35mA 523 24V to 32V 35mA 523 4V to 6V 100mA 1.30k 6V to 9V 100mA 1.30k 8V to 12V 100mA 1.30k 12V to 16V 100mA 1.30k 15V to 21V 100mA 1.30k 18V to 24V 100mA 1.30k 24V to 32V 100mA 1.30k 4V to 6V 350mA 4.75k 6V to 9V 350mA 4.75k 8V to 12V 350mA 4.75k 12V to 16V 350mA 4.75k 15V to 21V 350mA 4.75k 18V to 24V 350mA 4.75k 24V to 32V 350mA 4.75k 4V to 6V 500mA 7.32k 6V to 9V 500mA 7.32k 8V to 12V 500mA 7.32k 12V to 16V 500mA 7.32k 15V to 21V 500mA 7.32k 18V to 24V 500mA 7.32k 24V to 32V 500mA 7.32k 4V to 6V 700mA 11.8k 6V to 9V 700mA 11.8k 8V to 12V 700mA 11.8k 12V to 16V 700mA 11.8k 15V to 21V 700mA 11.8k 18V to 24V 700mA 11.8k 24V to 32V 700mA 11.8k 6V to 9V 1A Open 8V to 12V 1A Open 12V to 16V 1A Open 15V to 21V 1A Open 18V to 24V 1A Open 24V to 32V 1A Open RT f (OPTI- (OPTI- RT f MAL) MAL) (MIN) (MAX) 86.6k 250k 37.4k 500k 76.8k 275k 37.4k 500k 69.8k 300k 37.4k 500k 48.7k 400k 30.1k 600k 37.4k 500k 27.4k 650k 33.2k 550k 24.9k 700k 30.1k 600k 24.9k 700k 86.6k 250k 37.4k 500k 76.8k 275k 37.4k 500k 69.8k 300k 37.4k 500k 48.7k 400k 30.1k 600k 37.4k 500k 30.1k 600k 30.1k 600k 24.9k 700k 24.9k 700k 21.0k 800k 27.4k 650k 16.9k 950k 27.4k 650k 16.9k 950k 27.4k 650k 16.9k 950k 19.6k 850k 15.8k 1M 18.2k 900k 12.4k 1.2M 16.9k 950k 14.0k 1.1M 16.9k 950k 14.0k 1.1M 27.4k 650k 16.9k 950k 24.9k 700k 16.9k 950k 24.9k 700k 16.9k 950k 18.2k 900k 12.4k 1.2M 18.2k 900k 14.0k 1.1M 18.2k 900k 14.0k 1.1M 16.9k 950k 15.8k 1M 27.4k 650k 16.9k 950k 24.9k 700k 21.0k 800k 24.9k 700k 22.6k 750k 18.2k 900k 16.9k 950k 18.2k 900k 16.9k 950k 18.2k 900k 16.9k 950k 16.9k 950k 15.8k 1M 30.1k 600k 22.6k 750k 30.1k 600k 24.9k 700k 24.9k 700k 22.6k 750k 21.0k 800k 19.6k 850k 27.4k 650k 24.9k 700k 33.2k 550k 30.1k 600k 80421fa 20 LTM8042/LTM8042-1 APPLICATIONS INFORMATION Table 2. LTM8042 Recommended Values and Configuration for Buck Mode (TA = 25°C) VIN RANGE (BSTOUT/BKIN) VCC CVCC CIN (BSTOUT/BKIN TO GND) 4.4V to 5.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V LED STRING VOLTAGE (LED+ TO RT f COUT LED BSTIN/ (OPTI- (OPTI- RT f (BSTOUT/BKIN TO STRING BKLED–) CURRENT RCTL MAL) MAL) (MIN) (MAX) BSTIN/BKLED–) 2.2μF 1206 X7R 10V 2V to 4V 35mA 523 86.6k 250k 86.6k 250k 6.8V to 14V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1206 X7R 10V 4V to 6V 35mA 523 86.6k 250k 86.6k 250k 9.6V to 26V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1206 X7R 16V 6V to 9V 35mA 523 86.6k 250k 86.6k 250k 12.5V to 33V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1210 X7R 16V 8V to 12V 35mA 523 86.6k 250k 86.6k 250k 16.6V to 33V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1210 X7R 25V 12V to 16V 35mA 523 86.6k 250k 46.4k 420k 21.8V to 33V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1210 X7R 25V 15V to 21V 35mA 523 86.6k 250k 33.2k 550k 24.5V to 33V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1210 X7R 25V 18V to 24V 35mA 523 86.6k 250k 26.1k 670k 4.5V to 21V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1206 X7R 10V 2V to 4V 100mA 1.30k 86.6k 250k 86.6k 250k 6.8V to 33.8V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1206 X7R 10V 4V to 6V 100mA 1.30k 86.6k 250k 86.6k 250k 9.9V to 33.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 16V 6V to 9V 100mA 1.30k 76.8k 275k 69.8k 300k 13V to 33.4V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 16V 8V to 12V 100mA 1.30k 69.8k 300k 48.7k 400k 17.2V to 33.1V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 12V to 16V 100mA 1.30k 37.4k 500k 31.6k 575k 23V to 33V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 15V to 21V 100mA 1.30k 24.9k 700k 19.1k 870k 26V to 33V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 18V to 24V 100mA 1.30k 21.0k 800k 12.4k 1.2M 5.2V to 33.6V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1206 X7R 10V 2V to 4V 350mA 4.75k 61.9k 330k 54.9k 365k 7V to 33.4V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1206 X7R 10V 4V to 6V 350mA 4.75k 30.1k 600k 24.9k 700k 10.5V to 33.3V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 16V 6V to 9V 350mA 4.75k 21.0k 800k 15.8k 14.5V to 33.2V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 16V 8V to 12V 350mA 4.75k 12.4k 1.2M 8.25k 1.6M 1M 19.2V to 33V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 12V to 16V 350mA 4.75k 11.0k 1.3M 3.74k 2.5M 25V to 33V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 15V to 21V 350mA 4.75k 11.0k 1.3M 3.74k 2.5M 4.9V to 33V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1206 X7R 10V 2V to 4V 500mA 7.32k 37.4k 500k 33.2k 550k 7.3V to 33.2V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1206 X7R 10V 4V to 6V 500mA 7.32k 21.0k 800k 18.2k 900k 10.7V to 33V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 16V 6V to 9V 500mA 7.32k 15.8k 1M 11.0k 1.3M 14.1V to 32.8V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 16V 8V to 12V 500mA 7.32k 15.8k 1M 7.50k 1.7M 18.5V to 32.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 12V to 16V 500mA 7.32k 15.8k 1M 3.74 2.5M 24.3V to 32.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 15V to 21V 500mA 7.32k 15.8k 1M 3.74k 2.5M 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1206 X7R 10V 2V to 4V 700mA 11.8k 33.2k 550k 30.1k 600k 5V to 33.2V 3V to 30V 7.3V to 32.7V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1206 X7R 10V 4V to 6V 700mA 11.8k 21.0k 800k 18.2k 900k 10.8V to 32.7V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 16V 6V to 9V 700mA 11.8k 15.8k 14.4V to 32.2V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 16V 8V to 12V 700mA 11.8k 15.8k 1M 7.50k 1.7M 18.8V to 31.7V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 12V to 16V 700mA 11.8k 15.8k 1M 3.74k 2.5M 24.3V to 31.8V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 15V to 21V 700mA 11.8k 15.8k 1M 3.74k 2.5M 1M 11.0k 1.3M 5V to 32V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 50V 4.7μF 1206 X7R 10V 2V to 4V 1A Open 33.2k 550k 30.1k 600k 7.2V to 32V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 50V 4.7μF 1206 X7R 10V 4V to 6V 1A Open 21.0k 800k 16.9k 950k 10.8V to 31V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 50V 4.7μF 1210 X7R 16V 6V to 9V 1A Open 15.8k 1M 11.0k 1.3M 14.3V to 30.5V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 50V 4.7μF 1210 X7R 16V 8V to 12V 1A Open 15.8k 1M 7.50k 1.7M 18.9V to 30.5V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 50V 4.7μF 1210 X7R 25V 12V to 16V 1A Open 15.8k 1M 3.74k 2.5M 24.6V to 30.5V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 50V 4.7μF 1210 X7R 25V 15V to 21V 1A Open 15.8k 1M 3.74k 2.5M 80421fa 21 LTM8042/LTM8042-1 APPLICATIONS INFORMATION Table 3. LTM8042 Recommended Values and Configuration for Buck-Boost Mode (TA = 25°C) VIN RANGE (BSTIN/ BKLED–) 3V to 6V LED STRING VOLTAGE LED (LED+ to STRING RT f BSTIN/ CURR(OPTI- (OPTI- RT f BKLED–) ENT RCTL MAL) MAL) (MIN) (MAX) VCC CVCC (VCC to GND) CIN (BSTIN/BKLED– TO GND) COUT1 (BSTOUT/BKIN TO BSTIN/ BKLED–) COUT2 (BSTOUT/BKIN TO GND) 3V to 30V 1μF 0805 X7R 50V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 2V to 4V 35mA 523 86.6k 250k 86.6k 250k 3V to 14V 3V to 30V 1μF 0805 X7R 50V 1μF 0805 X7R 16V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 4V to 6V 35mA 523 86.6k 250k 86.6k 250k 3V to 20V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 6V to 9V 35mA 523 86.6k 250k 86.6k 250k 3V to 21V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 16V 1μF 0805 X7R 16V 8V to 12V 35mA 523 86.6k 250k 57.6k 350k 3V to 17.8V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 16V 1μF 1206 X7R 25V 12V to 16V 35mA 523 48.7k 400k 27.4k 650k 3V to 13V 3V to 30V 1μF 0805 X7R 50V 1μF 0805 X7R 16V 1μF 1206 X7R 25V 1μF 1206 X7R 25V 15V to 21V 35mA 523 37.4k 500k 10.0k 1.4M 3.5V to 10.1V 3V to 30V 1μF 0805 X7R 50V 1μF 0805 X7R 16V 1μF 1206 X7R 25V 1μF 1206 X7R 25V 18V to 24V 35mA 523 22.6k 750k 3.74k 2.5M 3V to 21V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 2V to 4V 100mA 1.30k 86.6k 250k 69.8k 300k 3V to 22.8V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 4V to 6V 100mA 1.30k 48.7k 400k 43.2k 450k 3V to 23.4V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 6V to 9V 100mA 1.30k 37.4k 500k 30.1k 600k 3V to 21.8V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 16V 1μF 1206 X7R 25V 8V to 12V 100mA 1.30k 21.0k 800k 16.9k 950k 3V to 17.9V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 16V 1μF 1206 X7R 25V 12V to 16V 100mA 1.30k 19.6k 850k 11.0k 1.3M 3V to 12.6V 3V to 30V 1μF 0805 X7R 50V 1μF 0805 X7R 16V 1μF 1206 X7R 25V 1μF 1206 X7R 25V 15V to 21V 100mA 1.30k 19.6k 850k 4.02k 2.4M 3.7V to 9.7V 3V to 30V 1μF 0805 X7R 50V 1μF 0805 X7R 10V 1μF 1206 X7R 25V 1μF 1206 X7R 25V 18V to 24V 100mA 1.30k 19.6k 850k 3.74k 2.5M 3V to 28V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 2V to 4V 350mA 4.75k 43.2k 450k 37.4k 500k 700k 3V to 27.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 4V to 6V 350mA 4.75k 33.2k 550k 24.9k 4.5V to 24.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 6V to 9V 350mA 4.75k 24.9k 700k 10.7k 1.35M 5.5V to 20.7V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 2.2μF 1206 X7R 16V 1μF 1206 X7R 25V 8V to 12V 350mA 4.75k 15.8k 1M 6.19k 1.9M 7V to 17.1V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 2.2μF 1206 X7R 16V 1μF 1206 X7R 25V 12V to 16V 350mA 4.75k 15.8k 1M 3.74k 2.5M 8.2V to 11.4V 3V to 30V 1μF 0805 X7R 50V 1μF 0805 X7R 16V 4.7μF 1210 X7R 25V 1μF 1206 X7R 25V 15V to 21V 350mA 4.75k 18.2k 900k 3.74k 2.5M 3V to 23V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 2V to 4V 500mA 7.32k 27.4k 650k 24.9k 700k 4.5V to 27V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 4V to 6V 500mA 7.32k 21.0k 800k 19.6k 850k 6V to 24V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 6V to 9V 500mA 7.32k 15.8k 1M 10.0k 1.4M 7.3V to 20.3V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 2.2μF 1206 X7R 16V 1μF 1206 X7R 25V 8V to 12V 500mA 7.32k 15.8k 1M 6.34k 1.85M 1μF 0805 X7R 16V 2.2μF 1206 X7R 16V 1μF 1206 X7R 25V 12V to 16V 500mA 7.32k 15.8k 9.4V to 15V 3V to 30V 1μF 0805 X7R 50V 1M 3.74k 2.5M 4.2V to 23.8V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 25V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 2V to 4V 700mA 11.8k 24.9k 700k 22.6k 750k 4.7V to 27V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 50V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 4V to 6V 700mA 11.8k 16.9k 950k 15.8k 1M 6.1V to 23V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 25V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 6V to 9V 700mA 11.8k 16.9k 950k 9.09k 1.5M 7.3V to 20V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 25V 2.2μF 1206 X7R 16V 1μF 1206 X7R 25V 8V to 12V 700mA 11.8k 16.9k 950k 6.19k 1.9M 10.5V to 16.5V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 25V 4.7μF 1210 X7R 16V 1μF 1206 X7R 25V 12V to 16V 700mA 11.8k 15.8k 4.7V to 28.5V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 50V 4.7μF 1206 X7R 10V 1μF 0805 X7R 10V 1M 3.74k 2.5M 2V to 4V 1A Open 24.9k 700k 22.6k 750k 6.7V to 26.8V 3V to 30V 1μF 0805 X7R 50V 2.2μF 1206 X7R 50V 4.7μF 1206 X7R 10V 1μF 0805 X7R 10V 4V to 6V 1A Open 22.6k 750k 16.9k 950k 9V to 23.5V 3V to 30V 1μF 0805 X7R 50V 4.7μF 1210 X7R 25V 4.7μF 1206 X7R 10V 1μF 0805 X7R 10V 6V to 9V 1A Open 22.6k 750k 10.0k 1.4M 13.5V to 20V 3V to 30V 1μF 0805 X7R 50V 4.7μF 1210 X7R 25V 4.7μF 1210 X7R 16V 1μF 1206 X7R 25V 8V to 12V 1A Open 22.6k 750k 5.76k 2M 80421fa 22 LTM8042/LTM8042-1 APPLICATIONS INFORMATION Table 4. LTM8042-1 Recommended Values and Configuration for Boost (TA = 25°C) VCC CIN (BSTIN/BKLED– TO GND) COUT (BSTOUT/BKIN TO GND) LED STRING VOLTAGE (LED+ TO GND) 1V to 3.3V 3V to 30V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 4V to 6V 1.2V to 5V 3V to 30V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 6V to 9V 35mA 1.27k 76.8k 275k 61.9k 330k 1.6V to 6V 3V to 30V 1μF 0805 X7R 10V 1μF 0805 X7R 16V 8V to 12V 35mA 1.27k 69.8k 300k 57.6k 350k VIN RANGE (BSTIN/ BKLED–) RT f LED (OPTI- (OPTI- RT f STRING CURRENT RCTL MAL) MAL) (MIN) (MAX) 35mA 1.27k 86.6k 250k 69.8k 300k 2.2V to 9.2V 3V to 30V 1μF 0805 X7R 10V 1μF 0805 X7R 16V 12V to 16V 35mA 1.27k 48.7k 400k 37.4k 500k 2.7V to 10V 3V to 30V 1μF 0805 X7R 16V 1μF 0805 X7R 25V 15V to 21V 35mA 1.27k 37.4k 500k 30.1k 600k 3V to 12.8V Connect to BSTIN/BKLED– 1μF 0805 X7R 16V 1μF 0805 X7R 25V 18V to 24V 35mA 1.27k 33.2k 550k 27.4k 650k 3.7V to 14.7V Connect to BSTIN/BKLED– 1μF 0805 X7R 16V 1μF 0805 X7R 50V 24V to 32V 35mA 1.27k 33.2k 550k 27.4k 650k 1.1V to 3.8V 3V to 30V 1μF 0805 X7R 10V 2.2μF 1206 X7R 10V 4V to 6V 100mA 3.40k 86.6k 250k 37.4k 500k 1.5V to 5.6V 3V to 30V 1μF 0805 X7R 16V 2.2μF 1206 X7R 10V 6V to 9V 100mA 3.40k 76.8k 275k 37.4k 500k 2.4V to 7.1V 3V to 30V 2.2μF 1206 X7R 10V 2.2μF 1206 X7R 16V 8V to 12V 100mA 3.40k 69.8k 300k 37.4k 500k 3.1V to 10.4V Connect to BSTIN/BKLED– 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 16V 12V to 16V 100mA 3.40k 48.7k 400k 30.1k 600k 4V to 12V Connect to BSTIN/BKLED– 2.2μF 1206 X7R 16V 2.2μF 1206 X7R 25V 15V to 21V 100mA 3.40k 37.4k 500k 30.1k 600k 4.9V to 14.9V Connect to BSTIN/BKLED– 1μF 0805 X7R 16V 2.2μF 1206 X7R 25V 18V to 24V 100mA 3.40k 30.1k 600k 24.9k 700k 6.1V to 18.8V Connect to BSTIN/BKLED– 1μF 0805 X7R 25V 2.2μF 1206 X7R 50V 24V to 32V 100mA 3.40k 24.9k 700k 21.0k 800k 2.4V to 3.8V 3V to 30V 1μF 0805 X7R 10V 4.7μF 0805 X7R 10V 4V to 6V 350mA 19.6k 27.4k 650k 16.9k 950k 2.8V to 5.3V 3V to 30V 1μF 0805 X7R 10V 2.2μF 1206 X7R 10V 6V to 9V 350mA 19.6k 27.4k 650k 16.9k 950k 3.2V to 7V Connect to BSTIN/BKLED– 1μF 0805 X7R 10V 2.2μF 1206 X7R 16V 8V to 12V 350mA 19.6k 27.4k 650k 16.9k 950k 4.1V to 10V Connect to BSTIN/BKLED– 1μF 1206 X7R 10V 2.2μF 1206 X7R 16V 12V to 16V 350mA 19.6k 19.6k 850k 15.8k 4.8V to 12.3V Connect to BSTIN/BKLED– 1μF 1206 X7R 16V 2.2μF 1206 X7R 25V 15V to 21V 350mA 19.6k 18.2k 900k 12.4k 1.2M 5.8V to 15V Connect to BSTIN/BKLED– 1μF 1206 X7R 16V 2.2μF 1206 X7R 25V 18V to 24V 350mA 19.6k 16.9k 950k 14.0k 1.1M 8.5V to 20.8V Connect to BSTIN/BKLED– 2.2μF 1206 X7R 25V 2.2μF 1206 X7R 50V 24V to 32V 350mA 19.6k 16.9k 950k 14.0k 1.1M 1M 80421fa 23 LTM8042/LTM8042-1 APPLICATIONS INFORMATION Table 5. LTM8042-1 Recommended Values and Configuration for Buck Mode (TA = 25°C) VIN RANGE (BSTOUT/ BKIN) VCC CVCC CIN (BSTOUT/BKIN TO GND) COUT (BSTOUT/BKIN TO BSTIN/BKLED–) LED STRING VOLTAGE (LED+ TO R f LED BSTIN/ (OPTI- (OPTI- RT f STRING BKLED–) CURRENT RCTL MAL) MAL) (MIN) (MAX) 4.3V to 8.3V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1206 X7R 10V 2V to 4V 35mA 1.27k 86.6k 250k 86.6k 250k 6.6V to 20V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1206 X7R 10V 4V to 6V 35mA 1.27k 86.6k 250k 86.6k 250k 9.5V to 31.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1206 X7R 16V 6V to 9V 35mA 1.27k 86.6k 250k 86.6k 250k 12.5V to 33V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1210 X7R 16V 8V to 12V 35mA 1.27k 86.6k 250k 86.6k 250k 16.6V to 33.2V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1210 X7R 25V 12V to 16V 35mA 1.27k 86.6k 250k 46.4k 420k 21.8V to 33.6V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1210 X7R 25V 15V to 21V 35mA 1.27k 86.6k 250k 33.2k 550k 24.4V to 33.1V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1210 X7R 25V 18V to 24V 35mA 1.27k 86.6k 250k 26.1k 670k 4.3V to 19.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1206 X7R 10V 2V to 4V 100mA 3.40k 86.6k 250k 86.6k 250k 6.5V to 33.8V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1206 X7R 10V 4V to 6V 100mA 3.40k 86.6k 250k 86.6k 250k 9.6V to 34.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 16V 6V to 9V 100mA 3.40k 76.8k 275k 57.6k 350k 12.6V to 34.4V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 16V 8V to 12V 100mA 3.40k 69.8k 300k 48.7k 400k 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 12V to 16V 100mA 3.40k 37.4k 500k 31.6k 575k 22.8V to 34.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 15V to 21V 100mA 3.40k 24.9k 700k 19.1k 870k 26.2V to 34.4V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 18V to 24V 100mA 3.40k 21.0k 800k 12.4k 1.2M 4.6V to 34.3V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1206 X7R 10V 2V to 4V 350mA 19.6k 61.9k 330k 54.9k 365k 6.7V to 34.3V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1206 X7R 10V 4V to 6V 350mA 19.6k 30.1k 600k 24.9k 700k 10.3V to 34.3V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 16V 6V to 9V 350mA 19.6k 21.0k 800k 15.8k 13.7V to 34.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 16V 8V to 12V 350mA 19.6k 19.6k 850k 8.25k 1.6M 18.6V to 34.6V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 12V to 16V 350mA 19.6k 14.0k 1.1M 3.74k 2.5M 24.1V to 34.3V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 15V to 21V 350mA 19.6k 15.8k 1M 3.74k 2.5M 27.3V to 32.8V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 4.7μF 1210 X7R 25V 18V to 24V 350mA 19.6k 15.8k 1M 3.74k 2.5M 17V to 34.5V 1M 80421fa 24 LTM8042/LTM8042-1 APPLICATIONS INFORMATION Table 6. LTM8042-1 Recommended Values and Configuration for Buck-Boost Mode (TA = 25°C) VIN RANGE (BSTIN/ BKLED–) 1V to 9.5V VCC CVCC (VCC TO GND) CIN (BSTIN/BKLED– TO GND) COUT1 (BSTOUT/BKIN TO BSTIN/ BKLED–) LED STRING VOLTAGE LED (LED+ TO STRING RT f COUT2 (OPTI- (OPTI- RT f (BSTOUT/BKIN BSTIN/ CURBKLED–) RENT RCTL MAL) MAL) (MIN) (MAX) TO GND) 3V to 30V 1μF 0805 X7R 50V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 2V to 4V 35mA 1.27k 86.6k 250k 86.6k 250k 1.1V to 21V 3V to 30V 1μF 0805 X7R 50V 1μF 0805 X7R 16V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 4V to 6V 35mA 1.27k 86.6k 250k 86.6k 250k 1.3V to 24V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 6V to 9V 35mA 1.27k 86.6k 250k 86.6k 250k 1.5V to 20.8V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 16V 1μF 0805 X7R 16V 8V to 12V 35mA 1.27k 86.6k 250k 43.2k 450k 2.2V to 16.9V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 16V 1μF 1206 X7R 25V 12V to 16V 35mA 1.27k 48.7k 400k 30.1k 600k 3V to 12V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 1206 X7R 25V 1μF 1206 X7R 25V 15V to 21V 35mA 1.27k 37.4k 500k 10.0k 1.4M 3.8V to 9V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 1206 X7R 25V 1μF 1206 X7R 25V 18V to 24V 35mA 1.27k 22.6k 750k 3.74k 2.5M 1.1V to 24V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 2V to 4V 100mA 3.40k 86.6k 250k 69.8k 300k 1.3V to 27V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 4V to 6V 100mA 3.40k 48.7k 400k 43.2k 450k 1.6V to 24V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 10V 1μF 0805 X7R 10V 6V to 9V 100mA 3.40k 37.4k 500k 33.2k 550k 1.9V to 21.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 16V 1μF 0805 X7R 16V 8V to 12V 100mA 3.40k 21.0k 800k 19.6k 850k 2.5V to 17V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 1μF 0805 X7R 16V 1μF 1206 X7R 25V 12V to 16V 100mA 3.40k 19.6k 850k 8.25k 1.6M 3V to 12V 3V to 30V 1μF 0805 X7R 50V 1μF 0805 X7R 16V 1μF 1206 X7R 25V 1μF 1206 X7R 25V 15V to 21V 100mA 3.40k 19.6k 850k 3.74k 2.5M 3.7V to 9V 3V to 30V 1μF 0805 X7R 50V 1μF 0805 X7R 10V 1μF 1206 X7R 25V 1μF 1206 X7R 25V 18V to 24V 100mA 3.40k 15.8k 1M 3.74k 2.5M 2.2V to 29V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 2V to 4V 350mA 19.6k 43.2k 450k 37.4k 500k 2.7V to 27.5V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 50V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 4V to 6V 350mA 19.6k 27.4k 650k 18.2k 900k 3.7V to 23.8V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 2.2μF 1206 X7R 10V 1μF 0805 X7R 10V 6V to 9V 350mA 19.6k 18.2k 900k 9.09k 1.5M 3.8V to 20.2V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 2.2μF 1206 X7R 16V 1μF 0805 X7R 16V 8V to 12V 350mA 19.6k 14.0k 1.1M 6.19k 1.9M 5.3V to 15.2V 3V to 30V 1μF 0805 X7R 50V 1μF 1206 X7R 25V 2.2μF 1206 X7R 16V 1μF 1206 X7R 25V 12V to 16V 350mA 19.6k 14.0k 1.1M 3.74k 2.5M 7.4V to 9.3V 3V to 30V 1μF 0805 X7R 50V 1μF 0805 X7R 16V 2.2μF 1206 X7R 16V 1μF 1206 X7R 25V 15V to 21V 350mA 19.6k 18.2k 900k 3.74k 2.5M 80421fa 25 LTM8042/LTM8042-1 APPLICATIONS INFORMATION Thermal Considerations The LTM8042/LTM8042-1 output current may need to be derated if it is required to operate in a high ambient temperature or deliver a large amount of continuous power. The amount of current derating is dependent upon the input voltage, output power and ambient temperature. The temperature rise curves given in the Typical Performance Characteristics section can be used as a guide. These curves were generated by an LTM8042/LTM8042-1 mounted to a 51cm2 4-layer FR4 printed circuit board. Boards of other sizes and layer count can exhibit different thermal behavior, so it is in-cumbent upon the user to verify proper operation over the intended system’s line, load and environmental operating conditions. The thermal resistance numbers listed in the Pin Configuration section of the data sheet are based on modeling the μModule package mounted on a test board specified per JESD51-9 (“Test Boards for Area Array Surface Mount Package Thermal Measurements”). The thermal coefficients provided are based on JESD 51-12 (“Guidelines for Reporting and Using Electronic Package Thermal Information”). For increased accuracy and fidelity to the actual application, many designers use finite element analysis (FEA) to predict thermal performance. To that end, the Pin Configuration section of the data sheet typically gives four thermal coefficients: 1. θJA : thermal resistance from junction to ambient. 2. θJCBOTTOM : thermal resistance from junction to the bottom of the product case. 3. θJCTOP : thermal resistance from junction to top of the product case. 4. θJB: thermal resistance from junction to the printed circuit board. While the meaning of each of these coefficients may seem to be intuitive, JEDEC has defined each to avoid confusion and inconsistency. These definitions are given in JESD 51-12, and are quoted or paraphrased in the following: 1. θJA is the natural convection junction-to-ambient air thermal resistance measured in a one cubic foot sealed enclosure. This environment is sometimes referred to as “still air” although natural convection causes the air to move. This value is determined with the part mounted to a JESD 51-9 defined test board, which does not reflect an actual application or viable operating condition. 2. θJCBOTTOM is the junction-to-board thermal resistance with all of the component power dissipation flowing through the bottom of the package. In the typical μModule regulator, the bulk of the heat flows out the bottom of the package, but there is always heat flow out into the ambient environment. As a result, this thermal resistance value may be useful for comparing packages but the test conditions don’t generally match the user’s application. 3. θJCTOP is determined with nearly all of the component power dissipation flowing through the top of the package. As the electrical connections of the typical μModule regulator are on the bottom of the package, it is rare for an application to operate such that most of the heat flows from the junction to the top of the part. As in the case of θJCBOTTOM, this value may be useful for comparing packages but the test conditions don’t generally match the user’s application. 4. θJB is the junction-to-board thermal resistance where almost all of the heat flows through the bottom of the μModule regulator and into the board, and is really the sum of the θJCBOTTOM and the thermal resistance of the bottom of the part through the solder joints and through a portion of the board. The board temperature is measured a specified distance from the package, using a two sided, two layer board. This board is described in JESD 51-9. 80421fa 26 LTM8042/LTM8042-1 APPLICATIONS INFORMATION The most appropriate way to use the coefficients is when running a detailed thermal analysis, such as FEA, which considers all of the thermal resistances simultaneously. None of them can be individually used to accurately predict the thermal performance of the product, so it would be inappropriate to attempt to use any one coefficient to correlate to the junction temperature versus load graphs given in the LTM8042/LTM8042-1 data sheet. The die temperature of the LTM8042/LTM8042-1 must be lower than the maximum rating of 125°C, so care should be taken in the layout of the circuit to ensure good heat sinking of the LTM8042/LTM8042-1. The bulk of the heat flow out of the LTM8042/LTM8042-1 is through the bottom of the module and the LGA pads into the printed circuit board. Consequently, a poor printed circuit board design can cause excessive heating, resulting in impaired performance or reliability. Please refer to the PCB Layout section for printed circuit board design suggestions. A graphical representation of these thermal resistances is given in Figure 5. The blue resistances are contained within the μModule regulator, and the green are outside. JUNCTION-TO-AMBIENT RESISTANCE (JESD 51-9 DEFINED BOARD) CASE (TOP)-TO-AMBIENT RESISTANCE JUNCTION-TO-CASE (TOP) RESISTANCE JUNCTION-TO-BOARD RESISTANCE JUNCTION At JUNCTION-TO-CASE CASE (BOTTOM)-TO-BOARD (BOTTOM) RESISTANCE RESISTANCE BOARD-TO-AMBIENT RESISTANCE 80421 F05 μMODULE DEVICE Figure 5 TYPICAL APPLICATIONS Boost Operation, Driving 6 White LEDs at 1A VIN 11.6V TO 19V VCC LTM8042 RUN LED+ UP TO 20.6V TG BSTIN/BKLED– PWM BSTOUT/BKIN SYNC 1A TGEN 4.7μF SS RT GND CTL 22.6k fSW = 750kHz 4.7μF 80421 TA02 80421fa 27 LTM8042/LTM8042-1 TYPICAL APPLICATIONS Buck-Boost Mode, Driving 5 White LEDs at 500mA with PWM Dimming Si2319DS LTM8042 VIN 7V TO 17.5V LED+ VCC UP TO 16.3V RUN PWM TG TGEN BSTOUT/BKIN SYNC BSTIN/BKLED– 500mA SS 1μF 1μF RT GND CTL 19.6k fSW = 850kHz 2.2μF 7.32k 80421 TA03 Buck Mode, Driving 4 White LEDs at 1A VIN 19V TO 30V VCC LTM8042 RUN LED+ UP TO 13.9V TG PWM BSTOUT/BKIN SYNC BSTIN/BKLED– 1A 2.2μF TGEN SS 1μF RT GND CTL 4.7μF 15.8k fSW = 1MHz 80421 TA04 Boost Operation, Driving 9 White LEDs at 100mA Si2319DS VIN 6V TO 22V UP TO 29V VCC LTM8042-1 LED+ RUN TG BSTIN/BKLED– PWM 100mA BSTOUT/BKIN TGEN SYNC 2.2μF SS RT GND CTL 2.2μF 24.9k fSW = 700kHz 3.4k 80421 TA05 80421fa 28 LTM8042/LTM8042-1 PACKAGE DESCRIPTION Pin Assignment Table (Arranged by Pin Number) PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME A1 GND B1 GND C1 GND D1 GND E1 GND F1 RUN A2 GND B2 GND C2 GND D2 GND E2 GND F2 GND A3 GND B3 GND C3 GND D3 GND E3 GND F3 GND A4 GND B4 GND C4 GND D4 GND E4 GND F4 GND A5 GND B5 GND C5 BSTIN/BKLED– D5 BSTIN/BKLED– E5 GND F5 GND A6 VCC B6 VCC C6 BSTIN/BKLED– D6 BSTIN/BKLED– E6 GND F6 GND A7 VCC B7 VCC C7 BSTIN/BKLED– D7 BSTIN/BKLED– E7 GND F7 GND PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME G1 SYNC H1 RT J1 SS K1 PWM L1 GND G2 GND H2 GND J2 GND K2 GND L2 CTL G3 GND H3 GND J3 GND K3 GND L3 TGEN G4 GND H4 GND J4 GND K4 GND L4 GND G5 BSTOUT/BKIN H5 BSTOUT/BKIN J5 BSTOUT/BKIN K5 LED+ L5 LED+ G6 BSTOUT/BKIN H6 BSTOUT/BKIN J6 BSTOUT/BKIN K6 LED+ L6 LED+ G7 BSTOUT/BKIN H7 BSTOUT/BKIN J7 TG K7 LED+ L7 LED+ PACKAGE PHOTOGRAPH 80421fa 29 0.9525 1.5875 4 PACKAGE TOP VIEW 9 BSC 2.540 3.810 15 BSC Y aaa Z DETAIL A 0.27 – 0.37 SUBSTRATE eee S X Y DETAIL B 0.635 ±0.025 SQ. 76x 2.45 – 2.55 MOLD CAP DETAIL B 2.72 – 2.92 6.350 5.080 3.810 2.540 1.270 DETAILS OF PAD #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE PAD #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE 4 SYMBOL TOLERANCE aaa 0.15 bbb 0.10 eee 0.05 6. THE TOTAL NUMBER OF PADS: 77 5. PRIMARY DATUM -Z- IS SEATING PLANE LAND DESIGNATION PER JESD MO-222, SPP-010 3 2. ALL DIMENSIONS ARE IN MILLIMETERS SUGGESTED PCB LAYOUT TOP VIEW 2.540 0.000 3.810 NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994 X // bbb Z 1.270 2.540 3.810 5.080 6.350 PAD 1 CORNER 1.270 aaa Z 0.000 0.9525 1.5875 (Reference LTC DWG # 05-08-1859 Rev Ø) Z 30 1.270 LGA Package 77-Lead (15mm × 9mm × 2.82mm) TRAY PIN 1 BEVEL COMPONENT PIN “A1” 3 PADS SEE NOTES 1.27 BSC 12.70 BSC 7 5 7.62 BSC 4 3 2 1 L K J H G F E D C B A PAD 1 DIA (0.635) LGA 77 (1859) 0709 REV Ø PACKAGE IN TRAY LOADING ORIENTATION LTMXXXXXX MModule PACKAGE BOTTOM VIEW 6 DETAIL A LTM8042/LTM8042-1 PACKAGE DESCRIPTION 80421fa LTM8042/LTM8042-1 REVISION HISTORY REV DATE DESCRIPTION A 01/11 Updated features. PAGE NUMBER 1 Updated ILED conditions in the Electrical Characteristics section. 3 Updated text in the Operation section. 15 Updated text in the Setting the Switching Frequency section. 16 80421fa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 31 LTM8042/LTM8042-1 TYPICAL APPLICATION Boost Operation, Driving 9 Red LEDs at 350mA with Analog Dimming UP TO 28V VIN 7V TO 24.8V VCC LTM8042 LED+ RUN BSTIN/BKLED– PWM TG BSTOUT/BKIN 350mA SYNC TGEN SS CTL GND RT 2.2μF ANALOG CONTROL VOLTAGE 2.2μF 19.6k fSW = 850kHz 80421 TA06 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTM8040 36V, 1A, μModule LED Driver and Current Source 4V ≤ VIN ≤ 36V; Open LED and Short-Circuit Protection, 9mm × 15mm × 4.32mm LGA Package LTM8032 EMC 36V, 2A, μModule Regulator EN55022 Class B Compliant; 0.8V ≤ VOUT ≤ 10V LTM4607 Buck-Boost μModule Regulator 4.5V ≤ VIN ≤ 36V; 0.8V ≤ VOUT ≤ 25V, 15mm × 15mm × 2.8mm 80421fa 32 Linear Technology Corporation LT 0111 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2010