LINER LTM8042IV-1PBF μmodule boost led driver and current source Datasheet

LTM8042/LTM8042-1
µModule Boost LED Driver
and Current Source
FEATURES
DESCRIPTION
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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
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n
n
n
n
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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
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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
●
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© LINEAR TECHNOLOGY CORPORATION 2010