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LTM8042/LTM8042-1 Module Boost LED Driver and Current Source FEATURES
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DESCRIPTION
The LTM(R)8042 is a complete Module(R) 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.
# WHITE LEDS 6 7 8 9 LED CURRENT 1A 350mA 1A 350mA 12VIN LTM8042 LTM8042-1 LTM8042 LTM8042-1 24VIN
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True Color PWMTM 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: <1A RoHS Compliant Package with Gold Pad Finish Tiny, Low Profile (9mm x 15mm x 2.82mm) Surface Mount LGA Package
APPLICATIONS
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Display Backlighting Automotive and Avionic Lighting Illumination Scanners
L, LT, LTC, LTM, Linear Technology, the Linear logo and Module are registered trademarks and True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
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
Module Boost LED Driver, Driving 8 White LEDs at 1A
UP TO 26.8V VIN 16V TO 26V VCC RUN BSTIN/BKLED- PWM SYNC TGEN 4.7F SS RT LTM8042 LED+ TG EFFICIENCY (%) 97 96 95 94 93 92 91 90 89 GND CTL 33.2k fSW = 550kHz 4.7F 88 87 16 17 18 19 20 21 22 23 24 25 26 VIN (V)
80421 TA01a 80421 TA01b
Efficiency vs VIN
BSTOUT/BKIN 1A
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LTM8042/LTM8042-1 ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
BSTIN/BKLED- TG 7 VCC BANK 2 6 BSTOUT/BKIN 5 4 BANK 1 3 GND 2 1 A B C D E F G H J K SS PWM L CTL TGEN LED+ BANK 3 BANK 4 BANK 5
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) ........................................... -40C to 125C Solder Temperature .............................................. 245C Storage Temperature ............................. -55C to 125C
RUN SYNC RT
LGA PACKAGE 77-LEAD (15mm 9mm 2.82mm) TJMAX = 125C, JA = 15.7C/W, JCtop = 13.6C/W, JCbottom = 4.5C/W, JB = 9.4C/W VALUES DETERMINED PER JESD 51-12 WEIGHT = 1.1g
ORDER INFORMATION
LEAD FREE FINISH LTM8042EV#PBF LTM8042IV#PBF LTM8042EV-1#PBF LTM8042IV-1#PBF TRAY LTM8042EV#PBF LTM8042IV#PBF LTM8042EV-1#PBF LTM8042IV-1#PBF PART MARKING* LTM8042V LTM8042V LTM8042-1V LTM8042-1V PACKAGE DESCRIPTION 77-Lead (15mm x 9mm x 2.82mm) LGA 77-Lead (15mm x 9mm x 2.82mm) LGA 77-Lead (15mm x 9mm x 2.82mm) LGA 77-Lead (15mm x 9mm x 2.82mm) LGA TEMPERATURE RANGE -40C to 125C -40C to 125C -40C to 125C -40C to 125C
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/
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LTM8042/LTM8042-1 ELECTRICAL CHARACTERISTICS
SYMBOL VCC(MIN) ILED PARAMETER Minimum Input DC Voltage LTM8042 LED Current LTM8042-1 LED Current RCTL = 6.81k VCLAMP IOUT/IOUT IQVCC fSW Open LED Clamp Voltage Output Current Line Regulation VCC Supply Current Switching Frequency Boost Mode, LED+ Open LTM8042, 6V < BSTOUT/BKIN < 30V LTM8042-1, 6V < BSTOUT/BKIN < 30V PWM = 0V RUN = 0V RT = 90.9k RT = 22.1k RT = 6.04k SS = 0.5V, Out of Pin VSYNC = 2V 1.5 CTL = 0V, Flows Out of Pin 1.5 0.4 60 1.5 0.4 60 Relative to LED+, 100k from LED+ to TG Relative to LED+, 100k from LED+ to TG PWM = 0V 1.5 0.4 100 200 0 -7 120 100 100 0.22 0.68 1.7 6 0.3 60 0.4 CTL Open CTL Open, RCTL = 6.81k
The l denotes the specifications which apply over the full internal operating temperature range, otherwise specifications are at TA = 25C. VCC = 5V, buck mode with 4 load.
CONDITIONS
l
MIN 3 0.9 0.45 0.34 0.17
TYP
MAX 1.05 0.55 0.39 0.20
UNITS V A A A A V % %
0.5
36 0.5 0.5 4.2 0.1 0.25 0.8 2 9 1 0.27 0.92 2.3 12 2.5
mA A MHz MHz MHz A MHz A V V A V V A V V A V V V V A
ISS fSYNC ISYNC VSYNC(IL) VSYNC(IH) ICTL VRUN(IH) VRUN(IL) IRUN VPWM(IH) VPWM(IL) IPWM VTG(OH) VTG(OL) VTGEN(IH) VTGEN(IL) ITGEN
Soft-Start Pin Current Synchronization Frequency Range SYNC Pull-Down Current (Into the Pin) SYNC Input Low SYNC Input High CTL Input Bias Current RUN Input Voltage High RUN Input Voltage Low RUN Pin Bias Current PWM Input Voltage High PWM Input Voltage Low PWM Pin Bias Current TG Output High Voltage TG Output Low Voltage TGEN Input Voltage High TGEN Input Voltage Low TGEN Pin Bias Current
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 0C to 125C ambient. Specifications over the full -40C to 125C internal operating temperature range are assured by design, characterization and correlation with statistical process controls.
The LTM8042I/LTM8042I-1 are guaranteed to meet specifications over the full -40C to 125C 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.
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LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS
LTM8042
Efficiency vs VIN, Boost Operation, 6.8V at 1A LED String
90 89 88 EFFICIENCY (%) EFFICIENCY (%) 87 86 85 84 83 82 81 80 4 5 VIN (V) 6
80421 G01
TA = 25C, unless otherwise noted. Efficiency vs VIN, Boost Operation, 13.4V at 1A LED String
95 94
Efficiency vs VIN, Boost Operation, 10.1V at 1A LED String
94 92 EFFICIENCY (%) 5 6 7 VIN (V)
80421 G02
93 92 91 90 89 88 87
90 88 86 84 82 80 8 9 10
86 85 7 8 9 10 VIN (V) 11 12 13
80421 G03
Efficiency vs VIN, Boost Operation, 16.7V at 1A LED String
97 94 92 EFFICIENCY (%) EFFICIENCY (%) 90 88 86 84 82 80 8 9 10 11 12 13 VIN (V) 14 15 16 95 93 91 89 87 85 83
Efficiency vs VIN, Boost Operation, 20.1V at 1A LED String
97 95 93 EFFICIENCY (%) 91 89 87 85 83 11 12 13 14 15 16 VIN (V) 17 18 19
Efficiency vs VIN, Boost Operation, 23.4V at 1A LED String
12 13 14 15 16 17 18 19 20 21 22 VIN (V)
80421 G06
80421 G04
80421 G05
Efficiency vs VIN, Boost Operation, 26.8V at 1A LED String
97 96 95 EFFICIENCY (%) EFFICIENCY (%) 94 93 92 91 90 89 88 87 16 17 18 19 20 21 22 23 24 25 26 VIN (V)
80421 G07
Efficiency vs VIN, Buck Mode, 3.5V at 1A LED String
89 87 EFFICIENCY (%) 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 VIN (V)
80421 G08
Efficiency vs VIN, Buck Mode, 6.8V at 1A LED String
94 92 90 88 86 84 82 80 8 10 12 14 16 18 20 22 24 26 28 30 32 34 VIN (V)
80421 G09
85 83 81 79 77 75
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LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS
LTM8042
Efficiency vs VIN, Buck Mode, 10.1V at 1A LED String
95 94 93 EFFICIENCY (%) 92 EFFICIENCY (%) 91 90 89 88 87 86 85 12 14 16 18 20 22 24 26 28 30 32 34 VIN (V)
80421 G10
TA = 25C, unless otherwise noted. Efficiency vs VIN, Buck Mode, 16.7V at 1A LED String
97 96 95 EFFICIENCY (%) 94 93 92 91 90 89 88 87
Efficiency vs VIN, Buck Mode, 13.4V at 1A LED String
97 96 95 94 93 92 91 90 89 88 87 15 17 19 21 23 25 27 29 31 33 VIN (V)
80421 G11
19
21
23
25 27 VIN (V)
29
31
33
80421 G12
Efficiency vs VIN, Buck-Boost Mode, 3.6V at 1A LED String
85 80 85 EFFICIENCY (%) EFFICIENCY (%) 90
Efficiency vs VIN, Buck-Boost Mode, 6.8V at 1A LED String
87 86 85 EFFICIENCY (%) 8 10 12 14 16 18 20 22 24 26 VIN (V)
80421 G14
Efficiency vs VIN, Buck-Boost Mode, 10.1V at 1A LED String
75 70 65 60 55 4 6 8 10 12 14 16 18 20 22 24 26 28 30 VIN (V)
80421 G13
84 83 82 81
80
75
70
80 12 13 14 15 16 17 18 19 20 21 22 23 24 VIN (V)
80421 G15
Efficiency vs VIN, Buck-Boost Mode, 13.4V at 1A LED String
90 89 88 EFFICIENCY (%) 87 86 85 84 83 82 81 80 15 16 17 18 VIN (V) 19 20
80421 G16
Maximum LED Current vs Input Voltage, Boost Operation
1200 1000 800 600 400 200 0 0 5 10 15 20 INPUT VOLTAGE (V) 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 25 30
MAXIMUM LED CURRENT (mA)
80421 G17
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LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS
LTM8042
Maximum LED Current vs VIN, Buck Mode
1000 900 800 LED CURRENT (mA) 700 600 500 400 300 200 100 0 0 5 10 15 VIN (N) 20 25 30 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 MAXIMUM LED CURRENT (mA) 1000 800 600 400 200 0 0 10 20 30 INPUT VOLTAGE (V) 40
80421 G19
TA = 25C, unless otherwise noted. Maximum LED Current vs Input Voltage, Buck-Boost Mode
1200
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
80421 G18
LED Current vs CTL Voltage
40 100 LED CURRENT SCALING (%) QUIESCENT CURRENT (mA) 80 60 40 20 0 0 200 400 600 800 1000 ADJUST VOLTAGE (mV) 1200 35 30
Quiescent Current vs Input Voltage, Open LED
25
Junction Temperature Rise vs Load, Boost Operation, 8.3V at 1A LED String
20 TEMPERATURE (C) 5VIN 15
25 20 15 10
10
5 5 0 0 5 10 15 20 INPUT VOLTAGE (V) 25 30 0 0 200 400 600 LED CURRENT (mA) 800 1000
80421 G22
80421 G20
80421 G21
Junction Temperature Rise vs Load, Boost Operation, 10.9V at 1A LED String
20 18 16 TEMPERATURE (C) TEMPERATURE (C) 14 12 10 8 6 4 2 0 0 200 400 600 LED CURRENT (mA) 800 1000
80421 G23
Junction Temperature Rise vs Load, Boost Operation, 13.6V at 1A LED String
25 35 30 20 TEMPERATURE (C) 8VIN 15 25 20 15 10 5 0 0 200 400 600 LED CURRENT (mA) 800 1000
80421 G24
Junction Temperature Rise vs Load, Boost Operation, 18.1V at 1A LED String
7VIN
9VIN
10
5
0 0 200 400 600 LED CURRENT (mA) 800 1000
80421 G25
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LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS
LTM8042
Junction Temperature Rise vs Load, Buck Mode, 2.9V at 1A LED String
18 16 14 TEMPERATURE (C) TEMPERATURE (C) 12 10 8 6 4 2 0 0 200 400 600 LED CURRENT (mA) 800 1000
80421 G26
TA = 25C, unless otherwise noted. Junction Temperature Rise vs Load, Buck Mode, 8.3V at 1A LED String
25
Junction Temperature Rise vs Load, Buck Mode, 3.8V at 1A LED String
18 16
TEMPERATURE (C)
24VIN
14 12 10 8 6 4 2 0 0 200
20 24VIN 24VIN 15
12VIN
12VIN
10 12VIN 5
0 400 600 LED CURRENT (mA) 800 1000
80421 G27
0
200
400 600 LED CURRENT (mA)
800
1000
80421 G28
Junction Temperature Rise vs Load, Buck Mode, 10.9V at 1A LED String
25 30 25 TEMPERATURE (C)
Junction Temperature Rise vs Load, Buck Mode, 13.6V at 1A LED String
25
Junction Temperature Rise vs Load, Buck Mode, 18.1V at 1A LED String
20 TEMPERATURE (C) 24VIN 15
20 TEMPERATURE (C) 24VIN 15
20 24VIN 15 10 5 0
10
10
5
5
0 0 200 400 600 LED CURRENT (mA) 800 1000
80421 G29
0 0 200 400 600 LED CURRENT (mA) 800 1000
80421 G30
0
200
400 600 LED CURRENT (mA)
800
1000
80421 G31
Junction Temperature Rise vs Load, Buck-Boost Mode, 2.9V at 1A LED String
25 30 25 TEMPERATURE (C) 24VIN 15 5VIN 20
Junction Temperature Rise vs Load, Buck-Boost Mode, 3.8V at 1A LED String
40 35 5VIN TEMPERATURE (C) 30
Junction Temperature Rise vs Load, Buck-Boost Mode, 8.3V at 1A LED String
20 TEMPERATURE (C)
12VIN 25 20 15 10
24VIN 15 12VIN 10 5 0
10
5 12VIN 0 0 200 400 600 LED CURRENT (mA) 800 1000
80421 G32
5 0 0 200 400 600 LED CURRENT (mA) 800 1000
80421 G33
0
200
400 600 LED CURRENT (mA)
800
1000
80421 G34
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LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS
LTM8042
Junction Temperature Rise vs Load, Buck-Boost Mode, 10.9V at 1A LED String
50 45 40 TEMPERATURE (C) TEMPERATURE (C) 35 30 25 20 15 10 5 0 0 200 400 600 LED CURRENT (mA) 800 1000
80421 G35
TA = 25C, unless otherwise noted. Junction Temperature Rise vs Load, Buck-Boost Mode, 15.5V at 350mA LED String
25
Junction Temperature Rise vs Load, Buck-Boost Mode, 13.6V at 1A LED String
60 50
20 TEMPERATURE (C) 12VIN 15
12VIN
40 12VIN 30 20 10 0 0 200 400 600 LED CURRENT (mA) 800 1000
80421 G36
16VIN
10
5
0 0 50 100 150 200 250 LED CURRENT (mA) 300 350
80421 G37
LTM8042/LTM8042-1
RUN Pin Current vs Voltage
160 140 120 RUN CURRENT (A) 100 80 60 40 20 0 0 10 20 30 RUN VOLTAGE (V) 40
80421 G38
LTM8042-1
Efficiency vs VIN, Boost Operation, 6.7V at 350mA LED String
95 90 EFFICIENCY (%) EFFICIENCY (%) 85 80 75 70 65 2 3 4 VIN (V) 5 6
80421 G39
Efficiency vs VIN, Boost Operation, 9.7V at 350mA LED String
95 90 85 80 75 70 65 2.5 4.5 VIN (V)
80421 G40
Efficiency vs VIN, Boost Operation, 12.6V at 350mA LED String
95 90 EFFICIENCY (%) 85 80 75 70 65
6.5
8.5
3
5
7 VIN (V)
9
11
80421 G41
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LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS
LTM8042-1
Efficiency vs VIN, Boost Operation, 15.6V at 350mA LED String
95 90 EFFICIENCY (%) 85 80 75 70 65 4 5 6 7 8 9 10 11 12 13 14 15 VIN (V)
80421 G42
TA = 25C, unless otherwise noted. Efficiency vs VIN, Boost Operation, 21.6V at 350mA LED String
95 90 EFFICIENCY (%) 85 80 75 70 65
Efficiency vs VIN, Boost Operation, 18.6V at 350mA LED String
95 90 EFFICIENCY (%) 85 80 75 70 65 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 VIN (V)
80421 G43
5 6 7 8 9 10 11 12 13 14 15 16 17 18 VIN (V)
80421 G44
Efficiency vs VIN, Boost Operation, 24.8V at 350mA LED String
93 91 89 EFFICIENCY (%) EFFICIENCY (%) 87 85 83 81 79 77 75 6 8 10 12 14 16 VIN (V) 18 20 22 24 93 91 89
Efficiency vs VIN, Buck Mode, 3.7V at 350mA LED String
96 94 92 EFFICIENCY (%) 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 VIN (V)
80421 G46
Efficiency vs VIN, Buck Mode, 6.7V at 350mA LED String
87 85 83 81 79 77 75
90 88 86 84 82 80 8 10 12 14 16 18 20 22 24 26 28 30 32 34 VIN (V)
80421 G47
80421 G45
Efficiency vs VIN, Buck Mode, 9.7V at 350mA LED String
98 96 95 94 EFFICIENCY (%) EFFICIENCY (%) 92 90 88 86 84 87 82 80 11 13 15 17 19 21 23 25 27 29 31 33 VIN (V)
80421 G48
Efficiency vs VIN, Buck Mode, 12.6V at 350mA LED String
97 97 95 EFFICIENCY (%) 14 16 18 20 22 24 VIN (V) 26 28 30 32 93 91 89 87 85
Efficiency vs VIN, Buck Mode, 15.6V at 350mA LED String
93 91 89
85
17
19
21
23
25 27 VIN (V)
29
31
33
80421 G50
80421 G49
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LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS
LTM8042-1
Efficiency vs VIN, Buck Mode, 18.6V at 350mA LED String
97 95 70 EFFICIENCY (%) EFFICIENCY (%) EFFICIENCY (%) 93 91 89 87 10 85 21 23 25 27 29 VIN (V) 31 33
80421 G51
TA = 25C, unless otherwise noted. Efficiency vs VIN, Buck-Boost Mode, 6.7V at 350mA LED String
90 85 80 75 70 65 60 55 50 45 40
Efficiency vs VIN, Buck-Boost Mode, 3.7V at 350mA LED String
90 80
60 50 40 30 20
0 0 10 20 VIN (V) 30 40
80421 G52
0
5
10
15 VIN (V)
20
25
30
80421 G53
Efficiency vs VIN, Buck-Boost Mode, 9.7V at 350mA LED String
90 85 80 EFFICIENCY (%) 75 70 65 60 55 50 0 5 10 15 VIN (V) 20 25 30 65 EFFICIENCY (%) 90 85
Efficiency vs VIN, Buck-Boost Mode, 12.6V at 350mA LED String
88 86 84 EFFICIENCY (%) 80 75 70 82 80 78 76 74 72 60 0 5 10 15 VIN (V) 20 25
80421 G55
Efficiency vs VIN, Buck-Boost Mode, 15.6V at 350mA LED String
70 0 10 VIN (V)
80421 G56
15
20
80421 G54
Efficiency vs VIN, Buck-Boost Mode, 18.6V at 350mA LED String
87 85 EFFICIENCY (%) 83 81 79 77 75 5 7 9 VIN (V)
80421 G57
Maximum LED Current vs Input Voltage, Boost Operation
400 350 MAXIMUM LED CURRENT (mA) MAXIMUM LED CURRENT (mA) 300 250 200 150 100 50 0 6.3V AT 350mA 15.5V AT 350mA 18.6V AT 350mA 21.7V AT 350mA 24.8V AT 350mA 0 5 10 15 INPUT VOLTAGE (V) 20 25
80421 G58
Maximum LED Current vs Input Voltage, Buck Mode
400 350 300 250 200 150 100 50 0 0 10 3.2V AT 350mA 6.3V AT 350mA 9.4V AT 350mA 12.4V AT 350mA 15.5V AT 350mA 18.6V AT 350mA 20 30 INPUT VOLTAGE (V) 40
80421 G59
11
13
15
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LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS
LTM8042-1
Maximum LED Current vs Input Voltage, Buck-Boost Mode
400 350 MAXIMUM LED CURRENT (mA) LED CURRENT SCALING (%) 300 250 200 150 100 50 0 0 3.2V AT 350mA 6.3V AT 350mA 9.4V AT 350mA 12.4V AT 350mA 15.5V AT 350mA 18.6V AT 350mA 10 20 30 INPUT VOLTAGE (V) 40
80421 G60
TA = 25C, unless otherwise noted. Quiescent Current vs Input Voltage, Open LED
80 70 QUIESCENT CURRENT (mA) 60 50 40 30 20 10 0
LED Current vs CTL Voltage
120 100 80 60 40 20 0 0 200 400 600 800 CTL VOLTAGE (mV) 1000 1200
0
5
10 15 20 25 INPUT VOLTAGE (V)
30
35
80421 G61
80421 G62
Junction Temperature Rise vs Load, Boost Operation, 6.8V at 350mA LED String
5 7 6 4
Junction Temperature Rise vs Load, Boost Operation, 9.4V at 350mA LED String
8 7 6 TEMPERATURE (C) 5VIN 4 3 2 1
Junction Temperature Rise vs Load, Boost Operation, 11.2V at 350mA LED String
TEMPERATURE (C)
TEMPERATURE (C)
5
5VIN 5 4 3 2 1 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350
3 5VIN 2
1
0 0 50 100 150 200 250 LED CURRENT (mA) 300 350
0 0 50 100 150 200 250 LED CURRENT (mA) 300 350
80421 G63
80421 G64
80421 G65
Junction Temperature Rise vs Load, Boost Operation, 15.5V at 350mA LED String
14 12 TEMPERATURE (C) TEMPERATURE (C) 10 5VIN 8 6 4 2 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350 10 9 8 7 6 5 4 3 2 1 0
Junction Temperature Rise vs Load, Buck Mode, 2.3V at 350mA LED String
6 5 TEMPERATURE (C) 4
Junction Temperature Rise vs Load, Buck Mode, 3.2V at 350mA LED String
24VIN
12VIN 3 2 5VIN 1 0
12VIN
0
50
100 150 200 250 LED CURRENT (mA)
300
350
0
50
100 150 200 250 LED CURRENT (mA)
300
350
80421 G66
80421 G67
80421 G68
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LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS
LTM8042-1
Junction Temperature Rise vs Load, Buck Mode, 6.8V at 350mA LED String
12 10 TEMPERATURE (C) 8 6 12VIN 4 2 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350 TEMPERATURE (C) 24VIN 14 12 TEMPERATURE (C) 10 24VIN 8 6 4 2 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350
TA = 25C, unless otherwise noted. Junction Temperature Rise vs Load, Buck Mode, 11.2V at 350mA LED String
14 12 10 24VIN 8 6 4 2 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350
Junction Temperature Rise vs Load, Buck Mode, 9.4V at 350mA LED String
80421 G69
80421 G70
80421 G71
Junction Temperature Rise vs Load, Buck Mode, 15.5V at 350mA LED String
14 12 8 TEMPERATURE (C) TEMPERATURE (C) 10 8 6 4 2 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350 0 10
Junction Temperature Rise vs Load, Buck-Boost Mode, 2.3V at 350mA LED String
12 24VIN TEMPERATURE (C) 10
Junction Temperature Rise vs Load, Buck-Boost Mode, 3.2V at 350mA LED String
24VIN 12VIN 8 12VIN 6 4 2 0 300 350 0 50 100 150 200 250 LED CURRENT (mA) 300 350 5VIN 3.3VIN
24VIN
6
4
2 3.3VIN 0 50
5VIN
100 150 200 250 LED CURRENT (mA)
80421 G72
80421 G73
80421 G74
Junction Temperature Rise vs Load, Buck-Boost Mode, 6.8V at 350mA LED String
12 10 TEMPERATURE (C) 8 6 5VIN 4 2 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350 TEMPERATURE (C) 12VIN 16 14 12 10
Junction Temperature Rise vs Load, Buck-Boost Mode, 9.4V at 350mA LED String
12VIN 8 5VIN 6 4 2 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350
80421 G75
80421 G76
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LTM8042/LTM8042-1 TYPICAL PERFORMANCE CHARACTERISTICS
LTM8042-1
Junction Temperature Rise vs Load, Buck-Boost Mode, 11.2V at 350mA LED String
18 16 25 14 TEMPERATURE (C) TEMPERATURE (C) 12 10 8 6 4 5 2 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350 0 0 50 100 150 200 250 LED CURRENT (mA) 300 350 5VIN 12VIN 20 15 12VIN 10 5VIN 30
TA = 25C, unless otherwise noted.
Junction Temperature Rise vs Load, Buck-Boost Mode, 15.5V at 350mA LED String
80421 G77
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.
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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
BSTIN/BKLED- 4.7H BSTOUT/BKIN
0.1F
1M
0.1F RSNS 0.10 (LTM8042) 0.27 (LTM8042-1)
VCC 0.1F OPEN LED PROTECTION (1V THRESHOLD) CURRENT MODE LED CONTROLLER
LED+
28.0k
RUN SS PWM 50k
CURRENT SENSE+ CURRENT SENSE- 2V 20.0k 1% TG
SYNC
GND
RT
TGEN
CTL
80421 BD
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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 1A 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.
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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) 250 500 800 1000 1500 2000 RT (k) 86.6 37.4 21.0 15.8 9.09 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.
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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. 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 VCC BSTIN/BKLED- RUN TGEN PWM SYNC SS RT GND CTL TG BSTOUT/BKIN LED+
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 (3s for SW = 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: PWMRATIO = TMAX TMIN (1)
A set of values that give a 3000:1 dimming ratio, for example, would be a switching frequency of SW = 2MHz, TMAX = 9ms and TMIN = 3s. Equation (1) becomes: PWMRATIO = 9ms/3s = 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.
80421 TA01a
Figure 1. The LTM8042/LTM8042-1 Can Control a P-Channel PWM Switch
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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. 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. 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.
TO LED STRING GND CIN VIN BSTIN/BKLED- COUT LED+ TG
VCC CVCC BSTOUT/BKIN
LED+
GND
TGEN CTL
80421 F02
PWM
SS
RUN
SYNC
GND
RT THERMAL VIAS TO GROUND PLANE
Figure 2. Suggested Layout for Boost Operation
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LTM8042/LTM8042-1 APPLICATIONS INFORMATION
TO LED STRING VIN CVCC BSTIN/BKLED- COUT CIN TG VIN
LED+
VCC BSTOUT/BKIN
LED+
GND
TGEN CTL
80421 F03
PWM
SS
RUN
SYNC
GND
RT THERMAL VIAS TO GROUND PLANE
Figure 3. Suggested Layout for Buck Mode
TO LED STRING
TO LED STRING
COUT1
COUT2 LED+ TG
VIN
CIN BSTIN/BKLED-
VCC CVCC BSTOUT/BKIN
LED+
TGEN CTL
80421 F04
PWM
SS
RUN
SYNC
GND
RT THERMAL VIAS TO GROUND PLANE
Figure 4. Suggested Layout for Buck-Boost Mode
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LTM8042/LTM8042-1 APPLICATIONS INFORMATION
Table 1. LTM8042 Recommended Values and Configuration for Boost (TA = 25C)
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 CIN (BSTIN/BKLED- TO GND) 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 16V 1F 0805 X7R 16V 4.7F 1206 X7R 10V 4.7F 1206 X7R 10V 4.7F 1206 X7R 10V 4.7F 1206 X7R 16V 4.7F 1206 X7R 16V 2.2F 1206 X7R 16V 2.2F 1206 X7R 25V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 1206 X7R 16V 1F 1206 X7R 16V 2.2F 1206 X7R 25V 1F 1206 X7R 10V 1F 1206 X7R 10V 1F 1206 X7R 10V 2.2F 1206 X7R 16V 2.2F 1206 X7R 16V 2.2F 1206 X7R 16V 2.2F 1206 X7R 25V 1F 1206 X7R 10V4 1F 1206 X7R 10V 1F 1206 X7R 10V 2.2F 1206 X7R 16V 2.2F 1206 X7R 16V 2.2F 1206 X7R 16V 2.2F 1206 X7R 25V 1F 1206 X7R 10V 1F 1206 X7R 10V 2.2F 1206 X7R 16V 2.2F 1206 X7R 16V 4.7F 1206 X7R 25V 4.7F 1206 X7R 25V COUT (BSTOUT/BKIN TO GND) 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 16V 1F 0805 X7R 16V 1F 0805 X7R 25V 1F 0805 X7R 25V 1F 0805 X7R 50V 2.2F 1206 X7R 10V 2.2F 1206 X7R 10V 2.2F 1206 X7R 16V 2.2F 1206 X7R 16V 2.2F 1206 X7R 25V 2.2F 1206 X7R 25V 2.2F 1206 X7R 50V 2.2F 1206 X7R 10V 2.2F 1206 X7R 10V 2.2F 1206 X7R 16V 2.2F 1206 X7R 16V 2.2F 1206 X7R 25V 2.2F 1206 X7R 25V 2.2F 1206 X7R 50V 2.2F 1206 X7R 10V 2.2F 1206 X7R 10V 2.2F 1206 X7R 16V 2.2F 1206 X7R 16V 4.7F 1206 X7R 25V 4.7F 1206 X7R 25V 4.7F 1206 X7R 50V 4.7F 1206 X7R 10V 4.7F 1206 X7R 10V 4.7F 1206 X7R 16V 4.7F 1206 X7R 16V 4.7F 1206 X7R 25V 4.7F 1206 X7R 25V 4.7F 1206 X7R 50V 4.7F 1206 X7R 10V 4.7F 1206 X7R 16V 4.7F 1206 X7R 16V 4.7F 1206 X7R 25V 4.7F 1206 X7R 25V 4.7F 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
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-
20
LTM8042/LTM8042-1 APPLICATIONS INFORMATION
Table 2. LTM8042 Recommended Values and Configuration for Buck Mode (TA = 25C)
CIN (BSTOUT/BKIN TO GND) 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 1F 1206 X7R 50V 2.2F 1206 X7R 50V 2.2F 1206 X7R 50V 2.2F 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-) 2.2F 1206 X7R 10V 2V to 4V 35mA 523 86.6k 250k 86.6k 250k 2.2F 1206 X7R 10V 2.2F 1206 X7R 16V 2.2F 1210 X7R 16V 2.2F 1210 X7R 25V 2.2F 1210 X7R 25V 2.2F 1210 X7R 25V 4.7F 1206 X7R 10V 4.7F 1206 X7R 10V 4.7F 1210 X7R 16V 4.7F 1210 X7R 16V 4.7F 1210 X7R 25V 4.7F 1210 X7R 25V 4.7F 1210 X7R 25V 4.7F 1206 X7R 10V 4.7F 1206 X7R 10V 4.7F 1210 X7R 16V 4.7F 1210 X7R 16V 4.7F 1210 X7R 25V 4.7F 1210 X7R 25V 4.7F 1206 X7R 10V 4.7F 1206 X7R 10V 4.7F 1210 X7R 16V 4.7F 1210 X7R 16V 4.7F 1210 X7R 25V 4.7F 1210 X7R 25V 4.7F 1206 X7R 10V 4.7F 1206 X7R 10V 4.7F 1210 X7R 16V 4.7F 1210 X7R 16V 4.7F 1210 X7R 25V 4.7F 1210 X7R 25V 4.7F 1206 X7R 10V 4.7F 1206 X7R 10V 4.7F 1210 X7R 16V 4V to 6V 6V to 9V 8V to 12V 12V to 16V 15V to 21V 18V to 24V 2V to 4V 4V to 6V 6V to 9V 8V to 12V 12V to 16V 15V to 21V 18V to 24V 2V to 4V 4V to 6V 6V to 9V 8V to 12V 12V to 16V 15V to 21V 2V to 4V 4V to 6V 6V to 9V 8V to 12V 12V to 16V 15V to 21V 2V to 4V 4V to 6V 6V to 9V 8V to 12V 12V to 16V 15V to 21V 2V to 4V 4V to 6V 6V to 9V 35mA 35mA 35mA 35mA 35mA 35mA 100mA 100mA 100mA 100mA 100mA 100mA 100mA 350mA 350mA 350mA 350mA 350mA 350mA 500mA 500mA 500mA 500mA 500mA 500mA 700mA 700mA 700mA 700mA 700mA 700mA 1A 1A 1A 1A 1A 1A 523 523 523 523 523 523 86.6k 250k 86.6k 250k 86.6k 250k 86.6k 250k 86.6k 250k 86.6k 250k 86.6k 250k 46.4k 420k 86.6k 250k 33.2k 550k 86.6k 250k 26.1k 670k
VIN RANGE (BSTOUT/BKIN) 4.4V to 5.5V 6.8V to 14V 9.6V to 26V 12.5V to 33V 16.6V to 33V 21.8V to 33V 24.5V to 33V 4.5V to 21V 6.8V to 33.8V 9.9V to 33.5V 13V to 33.4V 23V to 33V 26V to 33V 5.2V to 33.6V 7V to 33.4V
VCC 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V
CVCC 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V
1.30k 86.6k 250k 86.6k 250k 1.30k 86.6k 250k 86.6k 250k 1.30k 76.8k 275k 69.8k 300k 1.30k 69.8k 300k 48.7k 400k 1.30k 37.4k 500k 31.6k 575k 1.30k 24.9k 700k 19.1k 870k 1.30k 21.0k 800k 12.4k 1.2M 4.75k 61.9k 330k 54.9k 365k 4.75k 30.1k 600k 24.9k 700k 4.75k 21.0k 800k 15.8k 1M 4.75k 12.4k 1.2M 8.25k 1.6M 4.75k 11.0k 1.3M 3.74k 2.5M 4.75k 11.0k 1.3M 3.74k 2.5M 7.32k 37.4k 500k 33.2k 550k 7.32k 21.0k 800k 18.2k 900k 7.32k 15.8k 7.32k 15.8k 7.32k 15.8k 7.32k 15.8k 1M 1M 1M 1M 11.0k 1.3M 7.50k 1.7M 3.74 2.5M 3.74k 2.5M
17.2V to 33.1V 3V to 30V
10.5V to 33.3V 3V to 30V 14.5V to 33.2V 3V to 30V 19.2V to 33V 25V to 33V 4.9V to 33V 7.3V to 33.2V 10.7V to 33V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V
14.1V to 32.8V 3V to 30V 18.5V to 32.5V 3V to 30V 24.3V to 32.5V 3V to 30V 5V to 33.2V 7.3V to 32.7V 3V to 30V 3V to 30V
11.8k 33.2k 550k 30.1k 600k 11.8k 21.0k 800k 18.2k 900k 11.8k 15.8k 11.8k 15.8k 11.8k 15.8k 11.8k 15.8k 1M 1M 1M 1M 11.0k 1.3M 7.50k 1.7M 3.74k 2.5M 3.74k 2.5M
10.8V to 32.7V 3V to 30V 14.4V to 32.2V 3V to 30V 18.8V to 31.7V 3V to 30V 24.3V to 31.8V 3V to 30V 5V to 32V 7.2V to 32V 10.8V to 31V 3V to 30V 3V to 30V 3V to 30V
Open 33.2k 550k 30.1k 600k Open 21.0k 800k 16.9k 950k Open 15.8k Open 15.8k Open 15.8k Open 15.8k 1M 1M 1M 1M 11.0k 1.3M 7.50k 1.7M 3.74k 2.5M 3.74k 2.5M
80421fa
14.3V to 30.5V 3V to 30V 1F 0805 X7R 50V 2.2F 1206 X7R 50V 4.7F 1210 X7R 16V 8V to 12V 18.9V to 30.5V 3V to 30V 1F 0805 X7R 50V 2.2F 1206 X7R 50V 4.7F 1210 X7R 25V 12V to 16V 24.6V to 30.5V 3V to 30V 1F 0805 X7R 50V 2.2F 1206 X7R 50V 4.7F 1210 X7R 25V 15V to 21V
21
LTM8042/LTM8042-1 APPLICATIONS INFORMATION
Table 3. LTM8042 Recommended Values and Configuration for Buck-Boost Mode (TA = 25C)
VIN RANGE (BSTIN/ BKLED-)
3V to 6V 3V to 14V 3V to 20V 3V to 21V 3V to 17.8V 3V to 13V 3.5V to 10.1V 3V to 21V 3V to 22.8V 3V to 23.4V 3V to 21.8V 3V to 17.9V 3V to 12.6V 3.7V to 9.7V 3V to 28V 3V to 27.5V 4.5V to 24.5V 5.5V to 20.7V 7V to 17.1V 8.2V to 11.4V 3V to 23V 4.5V to 27V 6V to 24V 7.3V to 20.3V 9.4V to 15V 4.2V to 23.8V 4.7V to 27V 6.1V to 23V 7.3V to 20V 10.5V to 16.5V 4.7V to 28.5V 6.7V to 26.8V 9V to 23.5V 13.5V to 20V
VCC
3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V
CVCC (VCC to GND)
1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V 1F 0805 X7R 50V
CIN (BSTIN/BKLED- TO GND)
1F 0805 X7R 10V 1F 0805 X7R 16V 1F 1206 X7R 25V 1F 1206 X7R 25V 1F 1206 X7R 25V 1F 0805 X7R 16V 1F 0805 X7R 16V 1F 1206 X7R 25V 1F 1206 X7R 25V 1F 1206 X7R 25V 1F 1206 X7R 25V 1F 0805 X7R 16V 1F 0805 X7R 10V
COUT1 (BSTOUT/BKIN TO BSTIN/ BKLED-)
1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 16V 1F 0805 X7R 16V 1F 1206 X7R 25V 1F 1206 X7R 25V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 16V 1F 0805 X7R 16V 1F 1206 X7R 25V 1F 1206 X7R 25V
COUT2 (BSTOUT/BKIN TO GND)
1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 16V
LED STRING VOLTAGE LED (LED+ to STRING RT f BSTIN/ CURR(OPTI- (OPTI- RT f BKLED-) ENT RCTL MAL) MAL) (MIN) (MAX)
2V to 4V 4V to 6V 6V to 9V 8V to 12V 35mA 35mA 35mA 35mA 35mA 35mA 35mA 523 523 523 523 523 523 523 86.6k 86.6k 86.6k 86.6k 48.7k 37.4k 22.6k 250k 250k 250k 250k 400k 500k 750k 250k 400k 500k 800k 850k 850k 850k 450k 550k 700k 1M 1M 900k 650k 800k 1M 1M 1M 700k 950k 950k 950k 1M 700k 750k 750k 750k 86.6k 86.6k 86.6k 57.6k 27.4k 10.0k 3.74k 69.8k 43.2k 30.1k 16.9k 11.0k 4.02k 3.74k 37.4k 24.9k 6.19k 3.74k 3.74k 24.9k 19.6k 10.0k 3.74k 22.6k 15.8k 9.09k 6.19k 3.74k 22.6k 16.9k 10.0k 5.76k 250k 250k 250k 350k 650k 1.4M 2.5M 300k 450k 600k 950k 1.3M 2.4M 2.5M 500k 700k 1.9M 2.5M 2.5M 700k 850k 1.4M 2.5M 750k 1M 1.5M 1.9M 2.5M 750k 950k 1.4M 2M
1F 1206 X7R 25V 12V to 16V 1F 1206 X7R 25V 15V to 21V 1F 1206 X7R 25V 18V to 24V 2V to 4V 4V to 6V 6V to 9V 8V to 12V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 1206 X7R 25V
1F 1206 X7R 25V 2.2F 1206 X7R 10V 1F 0805 X7R 10V
100mA 1.30k 86.6k 100mA 1.30k 48.7k 100mA 1.30k 37.4k 100mA 1.30k 21.0k
1F 1206 X7R 25V 12V to 16V 100mA 1.30k 19.6k 1F 1206 X7R 25V 15V to 21V 100mA 1.30k 19.6k 1F 1206 X7R 25V 18V to 24V 100mA 1.30k 19.6k 2V to 4V 4V to 6V 6V to 9V 8V to 12V 350mA 4.75k 43.2k 350mA 4.75k 33.2k 350mA 4.75k 24.9k 350mA 4.75k 15.8k
1F 1206 X7R 50V 2.2F 1206 X7R 10V 1F 0805 X7R 10V 1F 1206 X7R 50V 2.2F 1206 X7R 10V 1F 0805 X7R 10V 1F 1206 X7R 25V 2.2F 1206 X7R 10V 1F 0805 X7R 10V 1F 1206 X7R 25V 2.2F 1206 X7R 16V 1F 1206 X7R 25V
10.7k 1.35M
1F 1206 X7R 25V 2.2F 1206 X7R 16V 1F 1206 X7R 25V 12V to 16V 350mA 4.75k 15.8k 1F 0805 X7R 16V 4.7F 1210 X7R 25V 1F 1206 X7R 25V 15V to 21V 350mA 4.75k 18.2k 1F 1206 X7R 25V 2.2F 1206 X7R 10V 1F 0805 X7R 10V 1F 1206 X7R 50V 2.2F 1206 X7R 10V 1F 0805 X7R 10V 1F 1206 X7R 25V 2.2F 1206 X7R 10V 1F 0805 X7R 10V 1F 1206 X7R 25V 2.2F 1206 X7R 16V 1F 1206 X7R 25V 2V to 4V 4V to 6V 6V to 9V 8V to 12V 2V to 4V 4V to 6V 6V to 9V 8V to 12V 2V to 4V 4V to 6V 6V to 9V 8V to 12V 500mA 7.32k 27.4k 500mA 7.32k 21.0k 500mA 7.32k 15.8k 500mA 7.32k 15.8k 700mA 11.8k 24.9k 700mA 11.8k 16.9k 700mA 11.8k 16.9k 700mA 11.8k 16.9k
6.34k 1.85M
1F 0805 X7R 16V 2.2F 1206 X7R 16V 1F 1206 X7R 25V 12V to 16V 500mA 7.32k 15.8k
1F 0805 X7R 50V 2.2F 1206 X7R 25V 2.2F 1206 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 50V 2.2F 1206 X7R 50V 2.2F 1206 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 50V 2.2F 1206 X7R 25V 2.2F 1206 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 50V 2.2F 1206 X7R 25V 2.2F 1206 X7R 16V 1F 1206 X7R 25V 1F 0805 X7R 50V 2.2F 1206 X7R 50V 4.7F 1206 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 50V 2.2F 1206 X7R 50V 4.7F 1206 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 50V 4.7F 1210 X7R 25V 4.7F 1206 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 50V 4.7F 1210 X7R 25V 4.7F 1210 X7R 16V 1F 1206 X7R 25V
1F 0805 X7R 50V 2.2F 1206 X7R 25V 4.7F 1210 X7R 16V 1F 1206 X7R 25V 12V to 16V 700mA 11.8k 15.8k
1A 1A 1A 1A
Open 24.9k Open 22.6k Open 22.6k Open 22.6k
80421fa
22
LTM8042/LTM8042-1 APPLICATIONS INFORMATION
Table 4. LTM8042-1 Recommended Values and Configuration for Boost (TA = 25C)
VIN RANGE (BSTIN/ BKLED-) 1V to 3.3V 1.2V to 5V 1.6V to 6V 2.2V to 9.2V 2.7V to 10V 3V to 12.8V 3.7V to 14.7V 1.1V to 3.8V 1.5V to 5.6V 2.4V to 7.1V 3.1V to 10.4V 4V to 12V CIN (BSTIN/BKLED- TO GND) 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 16V 1F 0805 X7R 16V 1F 0805 X7R 16V 1F 0805 X7R 10V 1F 0805 X7R 16V COUT (BSTOUT/BKIN TO GND) 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 16V 1F 0805 X7R 16V 1F 0805 X7R 25V 1F 0805 X7R 25V 1F 0805 X7R 50V 2.2F 1206 X7R 10V 2.2F 1206 X7R 10V LED STRING VOLTAGE (LED+ TO GND) 4V to 6V 6V to 9V 8V to 12V 12V to 16V 15V to 21V 18V to 24V 24V to 32V 4V to 6V 6V to 9V 8V to 12V RT f LED (OPTI- (OPTI- RT f STRING CURRENT RCTL MAL) MAL) (MIN) (MAX) 35mA 1.27k 86.6k 250k 69.8k 300k 35mA 35mA 35mA 35mA 35mA 35mA 100mA 100mA 100mA 100mA 100mA 100mA 100mA 350mA 350mA 350mA 350mA 350mA 350mA 350mA 1.27k 76.8k 1.27k 69.8k 1.27k 48.7k 1.27k 37.4k 1.27k 33.2k 1.27k 33.2k 3.40k 86.6k 3.40k 76.8k 3.40k 69.8k 3.40k 48.7k 3.40k 37.4k 3.40k 30.1k 3.40k 24.9k 19.6k 27.4k 19.6k 27.4k 19.6k 27.4k 19.6k 19.6k 19.6k 18.2k 19.6k 16.9k 19.6k 16.9k 275k 61.9k 330k 300k 57.6k 350k 400k 37.4k 500k 500k 30.1k 600k 550k 27.4k 650k 550k 27.4k 650k 250k 37.4k 500k 275k 37.4k 500k 300k 37.4k 500k 400k 30.1k 600k 500k 30.1k 600k 600k 24.9k 700k 700k 21.0k 800k 650k 16.9k 950k 650k 16.9k 950k 650k 16.9k 950k 850k 15.8k 1M 900k 12.4k 1.2M 950k 14.0k 1.1M 950k 14.0k 1.1M
VCC 3V to 30V 3V to 30V 3V to 30V 3V to 30V 3V to 30V Connect to BSTIN/BKLED- Connect to BSTIN/BKLED- 3V to 30V 3V to 30V 3V to 30V Connect to BSTIN/BKLED- Connect to BSTIN/BKLED-
2.2F 1206 X7R 10V 2.2F 1206 X7R 16V
2.2F 1206 X7R 16V 2.2F 1206 X7R 16V 12V to 16V 2.2F 1206 X7R 16V 2.2F 1206 X7R 25V 15V to 21V 1F 0805 X7R 16V 1F 0805 X7R 25V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 1206 X7R 10V 1F 1206 X7R 16V 1F 1206 X7R 16V 2.2F 1206 X7R 25V 18V to 24V 2.2F 1206 X7R 50V 24V to 32V 4.7F 0805 X7R 10V 2.2F 1206 X7R 10V 2.2F 1206 X7R 16V 4V to 6V 6V to 9V 8V to 12V
4.9V to 14.9V Connect to BSTIN/BKLED- 6.1V to 18.8V Connect to BSTIN/BKLED- 2.4V to 3.8V 2.8V to 5.3V 3.2V to 7V 4.1V to 10V 4.8V to 12.3V 5.8V to 15V 3V to 30V 3V to 30V Connect to BSTIN/BKLED- Connect to BSTIN/BKLED- Connect to BSTIN/BKLED- Connect to BSTIN/BKLED-
2.2F 1206 X7R 16V 12V to 16V 2.2F 1206 X7R 25V 15V to 21V 2.2F 1206 X7R 25V 18V to 24V
8.5V to 20.8V Connect to BSTIN/BKLED- 2.2F 1206 X7R 25V 2.2F 1206 X7R 50V 24V to 32V
80421fa
23
LTM8042/LTM8042-1 APPLICATIONS INFORMATION
Table 5. LTM8042-1 Recommended Values and Configuration for Buck Mode (TA = 25C)
LED STRING VOLTAGE (LED+ TO R f LED BSTIN/ (OPTI- (OPTI- RT f STRING BKLED-) CURRENT RCTL MAL) MAL) (MIN) (MAX) 2V to 4V 4V to 6V 6V to 9V 35mA 35mA 35mA 35mA 35mA 35mA 35mA 100mA 100mA 100mA 100mA 100mA 100mA 100mA 350mA 350mA 350mA 350mA 350mA 350mA 350mA 1.27k 86.6k 250k 86.6k 250k 1.27k 86.6k 250k 86.6k 250k 1.27k 86.6k 250k 86.6k 250k 1.27k 86.6k 250k 86.6k 250k 1.27k 86.6k 250k 46.4k 420k 1.27k 86.6k 250k 33.2k 550k 1.27k 86.6k 250k 26.1k 670k 3.40k 86.6k 250k 86.6k 250k 3.40k 86.6k 250k 86.6k 250k 3.40k 76.8k 275k 57.6k 350k 3.40k 69.8k 300k 48.7k 400k 3.40k 37.4k 500k 31.6k 575k 3.40k 24.9k 700k 19.1k 870k 3.40k 21.0k 800k 12.4k 1.2M 19.6k 61.9k 330k 54.9k 365k 19.6k 30.1k 600k 24.9k 700k 19.6k 21.0k 800k 15.8k 1M 19.6k 19.6k 850k 8.25k 1.6M 19.6k 14.0k 1.1M 3.74k 2.5M 19.6k 15.8k 19.6k 15.8k 1M 1M 3.74k 2.5M 3.74k 2.5M
VIN RANGE (BSTOUT/ BKIN) 4.3V to 8.3V 6.6V to 20V 9.5V to 31.5V 12.5V to 33V
VCC
CVCC
CIN (BSTOUT/BKIN TO GND)
COUT (BSTOUT/BKIN TO BSTIN/BKLED-)
3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 2.2F 1206 X7R 10V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 2.2F 1206 X7R 10V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 2.2F 1206 X7R 16V
3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 2.2F 1210 X7R 16V 8V to 12V
16.6V to 33.2V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 2.2F 1210 X7R 25V 12V to 16V 21.8V to 33.6V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 2.2F 1210 X7R 25V 15V to 21V 24.4V to 33.1V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 2.2F 1210 X7R 25V 18V to 24V 4.3V to 19.5V 6.5V to 33.8V 9.6V to 34.5V 17V to 34.5V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1206 X7R 10V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1206 X7R 10V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1210 X7R 16V 2V to 4V 4V to 6V 6V to 9V
12.6V to 34.4V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1210 X7R 16V 8V to 12V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1210 X7R 25V 12V to 16V 22.8V to 34.5V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1210 X7R 25V 15V to 21V 26.2V to 34.4V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1210 X7R 25V 18V to 24V 4.6V to 34.3V 6.7V to 34.3V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1206 X7R 10V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1206 X7R 10V 2V to 4V 4V to 6V 6V to 9V
10.3V to 34.3V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1210 X7R 16V
13.7V to 34.5V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1210 X7R 16V 8V to 12V 18.6V to 34.6V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1210 X7R 25V 12V to 16V 24.1V to 34.3V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1210 X7R 25V 15V to 21V 27.3V to 32.8V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 4.7F 1210 X7R 25V 18V to 24V
80421fa
24
LTM8042/LTM8042-1 APPLICATIONS INFORMATION
Table 6. LTM8042-1 Recommended Values and Configuration for Buck-Boost Mode (TA = 25C)
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) 2V to 4V 4V to 6V 6V to 9V 35mA 35mA 35mA 35mA 35mA 35mA 35mA 1.27k 86.6k 1.27k 86.6k 1.27k 86.6k 1.27k 86.6k 1.27k 48.7k 1.27k 37.4k 1.27k 22.6k 250k 250k 250k 250k 400k 500k 750k 250k 400k 500k 800k 850k 850k 1M 450k 650k 900k 86.6k 250k 86.6k 250k 86.6k 250k 43.2k 450k 30.1k 600k 10.0k 1.4M 3.74k 2.5M 69.8k 300k 43.2k 450k 33.2k 550k 19.6k 850k 8.25k 1.6M 3.74k 2.5M 3.74k 2.5M 37.4k 500k 18.2k 900k 9.09k 1.5M
VIN RANGE (BSTIN/ BKLED-) 1V to 9.5V
VCC
CVCC (VCC TO GND)
CIN (BSTIN/BKLED- TO GND)
3V to 30V 1F 0805 X7R 50V 1F 0805 X7R 10V 1F 0805 X7R 10V 1F 0805 X7R 10V
1.1V to 21V 3V to 30V 1F 0805 X7R 50V 1F 0805 X7R 16V 1F 0805 X7R 10V 1F 0805 X7R 10V 1.3V to 24V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 1F 0805 X7R 10V 1F 0805 X7R 10V
1.5V to 20.8V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 1F 0805 X7R 16V 1F 0805 X7R 16V 8V to 12V 2.2V to 16.9V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 1F 0805 X7R 16V 1F 1206 X7R 25V 12V to 16V 3V to 12V 3.8V to 9V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 1F 1206 X7R 25V 1F 1206 X7R 25V 15V to 21V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 1F 1206 X7R 25V 1F 1206 X7R 25V 18V to 24V 2V to 4V 4V to 6V 6V to 9V
1.1V to 24V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 2.2F 1206 X7R 10V 1F 0805 X7R 10V 1.3V to 27V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 1F 0805 X7R 10V 1F 0805 X7R 10V 1.6V to 24V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 1F 0805 X7R 10V 1F 0805 X7R 10V
100mA 3.40k 86.6k 100mA 3.40k 48.7k 100mA 3.40k 37.4k 100mA 3.40k 21.0k
1.9V to 21.5V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 1F 0805 X7R 16V 1F 0805 X7R 16V 8V to 12V 3V to 12V 3.7V to 9V
2.5V to 17V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 1F 0805 X7R 16V 1F 1206 X7R 25V 12V to 16V 100mA 3.40k 19.6k 3V to 30V 1F 0805 X7R 50V 1F 0805 X7R 16V 1F 1206 X7R 25V 1F 1206 X7R 25V 15V to 21V 100mA 3.40k 19.6k 3V to 30V 1F 0805 X7R 50V 1F 0805 X7R 10V 1F 1206 X7R 25V 1F 1206 X7R 25V 18V to 24V 100mA 3.40k 15.8k 2V to 4V 4V to 6V 6V to 9V 350mA 19.6k 43.2k 350mA 19.6k 27.4k 350mA 19.6k 18.2k 350mA 19.6k 14.0k
2.2V to 29V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 2.2F 1206 X7R 10V 1F 0805 X7R 10V 2.7V to 27.5V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 50V 2.2F 1206 X7R 10V 1F 0805 X7R 10V 3.7V to 23.8V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 2.2F 1206 X7R 10V 1F 0805 X7R 10V
3.8V to 20.2V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 2.2F 1206 X7R 16V 1F 0805 X7R 16V 8V to 12V
1.1M 6.19k 1.9M 1.1M 3.74k 2.5M 900k 3.74k 2.5M
5.3V to 15.2V 3V to 30V 1F 0805 X7R 50V 1F 1206 X7R 25V 2.2F 1206 X7R 16V 1F 1206 X7R 25V 12V to 16V 350mA 19.6k 14.0k 7.4V to 9.3V 3V to 30V 1F 0805 X7R 50V 1F 0805 X7R 16V 2.2F 1206 X7R 16V 1F 1206 X7R 25V 15V to 21V 350mA 19.6k 18.2k
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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 Module 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. JA : thermal resistance from junction to ambient. 2. JCBOTTOM : thermal resistance from junction to the bottom of the product case. 3. JCTOP : thermal resistance from junction to top of the product case. 4. JB: 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. JA 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. JCBOTTOM is the junction-to-board thermal resistance with all of the component power dissipation flowing through the bottom of the package. In the typical Module 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. JCTOP is determined with nearly all of the component power dissipation flowing through the top of the package. As the electrical connections of the typical Module 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 JCBOTTOM, this value may be useful for comparing packages but the test conditions don't generally match the user's application. 4. JB is the junction-to-board thermal resistance where almost all of the heat flows through the bottom of the Module regulator and into the board, and is really the sum of the JCBOTTOM 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.
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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. A graphical representation of these thermal resistances is given in Figure 5. The blue resistances are contained within the Module regulator, and the green are outside.
JUNCTION-TO-AMBIENT RESISTANCE (JESD 51-9 DEFINED BOARD) JUNCTION-TO-CASE (TOP) RESISTANCE CASE (TOP)-TO-AMBIENT RESISTANCE
The die temperature of the LTM8042/LTM8042-1 must be lower than the maximum rating of 125C, 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.
JUNCTION
JUNCTION-TO-BOARD RESISTANCE JUNCTION-TO-CASE CASE (BOTTOM)-TO-BOARD (BOTTOM) RESISTANCE RESISTANCE BOARD-TO-AMBIENT RESISTANCE
At
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MODULE DEVICE
Figure 5
TYPICAL APPLICATIONS
Boost Operation, Driving 6 White LEDs at 1A
VIN 11.6V TO 19V VCC RUN BSTIN/BKLED- PWM SYNC TGEN 4.7F SS RT GND CTL 22.6k fSW = 750kHz 4.7F BSTOUT/BKIN 1A LTM8042 LED+ TG UP TO 20.6V
80421 TA02
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27
LTM8042/LTM8042-1 TYPICAL APPLICATIONS
Buck-Boost Mode, Driving 5 White LEDs at 500mA with PWM Dimming
VIN 7V TO 17.5V LTM8042 VCC RUN PWM TGEN SYNC SS 1F RT GND CTL 19.6k fSW = 850kHz 2.2F TG BSTOUT/BKIN BSTIN/BKLED- 1F 500mA LED+ Si2319DS UP TO 16.3V
7.32k
80421 TA03
Buck Mode, Driving 4 White LEDs at 1A
VIN 19V TO 30V
VCC RUN PWM SYNC TGEN SS 1F RT
LTM8042
LED+ TG
UP TO 13.9V
BSTOUT/BKIN BSTIN/BKLED- 2.2F 4.7F 1A
GND CTL 15.8k fSW = 1MHz
80421 TA04
Boost Operation, Driving 9 White LEDs at 100mA
Si2319DS UP TO 29V
VIN 6V TO 22V
VCC LTM8042-1 LED+ RUN BSTIN/BKLED- PWM TGEN SYNC 2.2F SS RT GND CTL 2.2F 24.9k fSW = 700kHz 3.4k BSTOUT/BKIN 100mA TG
80421 TA05
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28
LTM8042/LTM8042-1 PACKAGE DESCRIPTION
Pin Assignment Table (Arranged by Pin Number)
PIN A1 A2 A3 A4 A5 A6 A7 PIN G1 G2 G3 G4 G5 G6 G7 NAME GND GND GND GND GND VCC VCC NAME SYNC GND GND GND BSTOUT/BKIN BSTOUT/BKIN BSTOUT/BKIN PIN B1 B2 B3 B4 B5 B6 B7 PIN H1 H2 H3 H4 H5 H6 H7 NAME GND GND GND GND GND VCC VCC NAME RT GND GND GND BSTOUT/BKIN BSTOUT/BKIN BSTOUT/BKIN PIN C1 C2 C3 C4 C5 C6 C7 PIN J1 J2 J3 J4 J5 J6 J7 NAME GND GND GND GND BSTIN/BKLED- BSTIN/BKLED- BSTIN/BKLED- NAME SS GND GND GND BSTOUT/BKIN BSTOUT/BKIN TG PIN D1 D2 D3 D4 D5 D6 D7 PIN K1 K2 K3 K4 K5 K6 K7 NAME GND GND GND GND BSTIN/BKLED- BSTIN/BKLED- BSTIN/BKLED- NAME PWM GND GND GND LED+ LED+ LED+ PIN E1 E2 E3 E4 E5 E6 E7 PIN L1 L2 L3 L4 L5 L6 L7 NAME GND GND GND GND GND GND GND NAME GND CTL TGEN GND LED+ LED+ LED+ PIN F1 F2 F3 F4 F5 F6 F7 NAME RUN GND GND GND GND GND GND
PACKAGE PHOTOGRAPH
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29
LGA Package 77-Lead (15mm x 9mm x 2.82mm)
(Reference LTC DWG # 05-08-1859 Rev O)
DETAIL A X Y A B C D E 15 BSC MOLD CAP SUBSTRATE G 0.27 - 0.37 2.45 - 2.55 Z 1.27 BSC H J K L aaa Z PADS SEE NOTES 3 DETAIL B 2.540 3.810 0.635 0.025 SQ. 76x eee S X Y 7.62 BSC 12.70 BSC F 2.72 - 2.92 7 6 5 4 3 2 1 PAD 1 DIA (0.635)
LTM8042/LTM8042-1
// bbb Z
3.810
2.540
1.270
0.000
6.350
5.080
3.810 DETAIL A
2.540
1.270
1.270
0.9525 1.5875
30
PACKAGE DESCRIPTION
DETAIL B
aaa Z
9 BSC
PAD 1 CORNER
4
PACKAGE TOP VIEW
PACKAGE BOTTOM VIEW
NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994 2. ALL DIMENSIONS ARE IN MILLIMETERS 3 4 LAND DESIGNATION PER JESD MO-222, SPP-010
COMPONENT PIN "A1"
0.000
0.9525 1.5875
1.270
LTMXXXXXX Module
2.540
3.810
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
5.080
5. PRIMARY DATUM -Z- IS SEATING PLANE 6. THE TOTAL NUMBER OF PADS: 77 SYMBOL TOLERANCE aaa 0.15 bbb 0.10 eee 0.05
TRAY PIN 1 BEVEL
6.350
PACKAGE IN TRAY LOADING ORIENTATION
LGA 77 (1859) 0709 REV O
SUGGESTED PCB LAYOUT TOP VIEW
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LTM8042/LTM8042-1 REVISION HISTORY
REV A DATE 01/11 DESCRIPTION Updated features. Updated ILED conditions in the Electrical Characteristics section. Updated text in the Operation section. Updated text in the Setting the Switching Frequency section. PAGE NUMBER 1 3 15 16
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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 RUN
LTM8042 LED+ TG
BSTIN/BKLED- PWM SYNC TGEN 2.2F ANALOG CONTROL VOLTAGE SS CTL GND RT
BSTOUT/BKIN 350mA
2.2F 19.6k fSW = 850kHz
80421 TA06
RELATED PARTS
PART NUMBER LTM8040 LTM8032 LTM4607 DESCRIPTION 36V, 1A, Module LED Driver and Current Source EMC 36V, 2A, Module Regulator Buck-Boost Module Regulator COMMENTS 4V VIN 36V; Open LED and Short-Circuit Protection, 9mm x 15mm x 4.32mm LGA Package EN55022 Class B Compliant; 0.8V VOUT 10V 4.5V VIN 36V; 0.8V VOUT 25V, 15mm x 15mm x 2.8mm
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32 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT 0111 REV A * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2010

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