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LT3478IFE-1#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24
LT3478/LT3478-1
1
34781f
V
IN
(V)
8
EFFICIENCY (%)
100
95
90
85
80
1210
3478 TA01b
14 16
I
LED
= 700mA
f
OSC
= 500kHz
PWM DUTY CYCLE = 100%
6 LEDs LUXEON III (WHITE)
4.5A Monolithic LED
Drivers with True Color
PWM Dimming
■
High Power LED Driver
■
Automotive Lighting
■
True Color PWM™ Dimming Delivers Constant LED
Color with Up to 3000:1 Range
■
Wide Input Voltage Range: 2.8V to 36V
■
4.5A, 60mΩ, 42V Internal Switch
■
Drives LEDs in Boost, Buck-Boost or Buck Modes
■
Integrated Resistors for Inductor and LED Current
Sensing
■
Program LED Current:
100mA to 1050mA (LT3478-1)
(10mV to 105mV)/R
SENSE
(LT3478)
■
Program LED Current De-Rating vs Temperature
■
Separate Inductor Supply Input
■
Inrush Current Protection
■
Programmable Soft-Start
■
Fixed Frequency Operation from 200kHz to 2.25MHz
■
Open LED Protection (Programmable OVP)
■
Accurate Shutdown/UVLO Threshold with
Programmable Hysteresis
■
16-Pin Thermally Enhanced TSSOP Package
Automotive TFT LCD Backlight
APPLICATIO S
U
FEATURES
DESCRIPTIO
U
TYPICAL APPLICATIO
U
Effi ciency vs V
IN
LT3478-1
SHDN
V
REF
OUT
LED
CTRL2
OVPSET
CTRL1
PWM SS V
C
R
T
V
IN
V
S
LSW
10µF
4.7µF
45.3k
54.9k
69.8k
130k
0.1Ω
R
SENSE
(LT3478)
PWM DIMMING
CONTROL
700mA
15W
6 LEDs
(WHITE)
3478 TA01
10µH
V
IN
8V TO 16V
0.1µF1µF
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Patents Pending.
The LT
®
3478/LT3478-1 are 4.5A step-up DC/DC convert-
ers designed to drive LEDs with a constant current over
a wide programmable range. Series connection of the
LEDs provides identical LED currents for uniform bright-
ness without the need for ballast resistors and expensive
factory calibration.
The LT3478-1 reduces external component count and cost
by integrating the LED current sense resistor. The LT3478
uses an external sense resistor to extend the maximum
programmable LED current beyond 1A and also to achieve
greater accuracy when programming low LED currents.
Operating frequency can be set with an external resistor
from 200kHz up to 2.25MHz. Unique circuitry allows a
PWM dimming range up to 3000:1 while maintaining
constant LED color. The LT3478/LT3478-1 are ideal for
high power LED driver applications such as automotive TFT
LCD backlights, courtesy lighting and heads-up displays.
One of two CTRL pins can be used to program maximum
LED current. The other CTRL pin can be used to program
a reduction in maximum LED current vs temperature to
maximize LED usage and improve reliability.
Additional features include inrush current protection,
programmable open LED protection and programmable
soft-start. Each part is available in a 16-pin thermally
enhanced TSSOP Package.
LT3478/LT3478-1
2
34781f
SW ............................................................................42V
V
OUT
, LED ..................................................................42V
V
IN
, V
S
, V
L
,
⎯
S
⎯
H
⎯
D
⎯
N (Note 5) .......................................36V
PWM .........................................................................15V
CTRL1, 2 .....................................................................6V
SS, R
T
, V
C
, V
REF
, OVPSET ............................................2V
Operating Junction Temperature Range
(Notes 2, 3, 4) .................................... –40°C to 125°C
Storage Temperature Range ................... –65°C to 150°C
Lead Temperature (Soldering, 10 Sec) .................. 300°C
(Note 1)
The
● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. SW = open, V
IN
= V
S
= L = V
OUT
=
⎯
S
⎯
H
⎯
D
⎯
N = 2.7V, LED = open, SS = open,
PWM = CTRL1, CTRL2 = 1.25V, V
REF
= open, V
C
= open, R
T
= 31.6k.
ELECTRICAL CHARACTERISTICS
ABSOLUTE AXI U RATI GS
W
WW
U
PACKAGE/ORDER I FOR ATIO
UUW
FE PACKAGE
16-LEAD PLASTIC TSSOP
1
2
3
4
5
6
7
8
TOP VIEW
16
15
14
13
12
11
10
9
17
SW
SW
V
IN
V
S
L
V
OUT
LED
OVPSET
SS
R
T
PWM
CTRL2
CTRL1
SHDN
V
REF
V
C
T
JMAX
= 125°C, θ
JA
= 35°C/W
EXPOSED PAD (PIN 17) IS PGND, MUST BE SOLDERED TO PCB.
ORDER PART NUMBER FE PART MARKING
LT3478EFE
LT3478EFE-1
LT3478IFE
LT3478IFE-1
3478FE
3478FE-1
3478FE
3478FE-1
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Operating Voltage (Rising)
●
2.4 2.8 V
Operational Input Voltage V
S
V
IN
(Note 5)
2.8
2.8
36
36
V
V
V
IN
Quiescent Current V
C
= 0V (No Switching) 6.1 mA
V
IN
Shutdown Current
⎯
S
⎯
H
⎯
D
⎯
N = 0V 3 6 µA
⎯
S
⎯
H
⎯
D
⎯
N Pin Threshold (V
SD_µp
) (Micropower)
●
0.1 0.4 0.7 V
⎯
S
⎯
H
⎯
D
⎯
N Pin Threshold (V
SD_UVLO
) (Switching) 1.3 1.4 1.5 V
⎯
S
⎯
H
⎯
D
⎯
N Pin Current
⎯
S
⎯
H
⎯
D
⎯
N = V
SD_UVLO
– 50mV
⎯
S
⎯
H
⎯
D
⎯
N = V
SD_UVLO
+ 50mV
810
0
12 µA
µA
V
REF
Voltage I(V
REF
) = 0µA, V
C
= 0V
●
1.213 1.240 1.263 V
V
REF
Line Regulation I(V
REF
) = 0µA, 2.7V < V
IN
< 36V 0.005 0.015 %/V
V
REF
Load Regulation 0 < I(V
REF
) < 100µA (Max) 8 12 mV
Frequency: f
OSC
200kHz R
T
= 200k 0.18 0.2 0.22 MHz
Frequency: f
OSC
1MHz R
T
= 31.6k
●
0.88 1.12 MHz
LT3478/LT3478-1
3
34781f
The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. SW = open, V
IN
= V
S
= L = V
OUT
=
⎯
S
⎯
H
⎯
D
⎯
N = 2.7V, LED = open, SS = open,
PWM = CTRL1, CTRL2 = 1.25V, V
REF
= open, V
C
= open, R
T
= 31.6k.
ELECTRICAL CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS
Frequency: f
OSC
2.25MHz R
T
= 9.09k 2 2.25 2.6 MHz
Line Regulation f
OSC
R
T
= 31.6k, 2.7V < V
IN
< 36V 0.05 0.2 %/V
Nominal R
T
Pin Voltage 0.64 V
Maximum Duty Cycle R
T
= 31.6k
R
T
= 200k
R
T
= 9.09k
●
80 88
97
73
%
%
%
LED Current to V
C
Current Gain (Note 6) 770 µA/A
LED Current to V
C
Voltage Gain (Note 6) 400 V/A
V
C
to Switch Current Gain 13 A/V
V
C
Source Current (Out of Pin) CTRL1 = 0.4V, V
C
= 1V 40 µA
V
C
Sink Current CTRL1 = 0V, V
C
= 1V 40 µA
V
C
Switching Threshold 0.65 V
V
C
High Level (V
OH
) CTRL1 = 0.4V 1.5 V
V
C
Low Level (V
OL
) CTRL1 = 0V 0.2 V
Inductor Current Limit 2.7V < V
S
< 36V
●
4.5 6 6.8 A
Switch Current Limit
●
4.5 6.3 7.5 A
Switch V
CE
SAT I
SW
= 4.5A 270 mV
Switch Leakage Current SW = 42V, V
C
= 0V 1 µA
V
OUT
Overvoltage Protection (OVP)
(Rising)
OVPSET = 1V
OVPSET = 0.3V
41
12.3
V
V
Full Scale LED Current (LT3478-1) CTRL1 = V
REF
, Current Out of LED Pin 1010 1050 1090 mA
700mA LED Current (LT3478-1) CTRL1 = 700mV, Current Out of LED Pin
●
655 700 730 mA
350mA LED Current (LT3478-1) CTRL1 = 350mV, Current Out of LED Pin 325 350 375 mA
100mA LED Current (LT3478-1) CTRL1 = 100mV, Current Out of LED Pin 70 100 130 mA
Full Scale LED Current V
SENSE
(LT3478) CTRL1 = V
REF
, V
SENSE
= V
VOUT
– V
LED
101 105 109 mV
CTRL1 = 700mV, V
SENSE
(LT3478) CTRL1 = 700mV, V
SENSE
= V
VOUT
– V
LED
●
67 70.5 74 mV
CTRL1 = 350mV, V
SENSE
(LT3478) CTRL1 = 350mV, V
SENSE
= V
VOUT
– V
LED
33 35.5 38 mV
CTRL1 = 100mV, V
SENSE
(LT3478) CTRL1 = 100mV, V
SENSE
= V
VOUT
– V
LED
71013 mV
CTRL1, 2 Input Currents CTRL1 = 100mV, CTRL2 = 1.25V or
CTRL2 = 100mV, CTRL1 = 1.25V (Current Out of Pin)
40 nA
OVPSET Input Current OVPSET = 1V, V
OUT
= 41V (Current Out of Pin) 200 nA
PWM Switching Threshold 0.8 1 1.2 V
V
C
Pin Current in PWM Mode V
C
= 1V, PWM = 0 1 50 nA
OUT Pin Current in PWM Mode PWM = 0 1 100 nA
SS Low Level (V
OL
)I
(SS)
= 20µA 0.15 V
SS Reset Threshold V
C
= 0V 0.25 V
SS High Level (V
OH
)V
C
= 0V 1.5 V
Soft-Start (SS) Pin Charge Current SS = 1V, Current Out of Pin, V
C
= 0V 12 µA
Soft-Start (SS) Pin Discharge Current SS = 0.5V, V
C
= 0V 350 µA
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LT3478IFE-1#TRPBF

Mfr. #:
Buy LT3478IFE-1#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
LED Lighting Drivers 4.5A 42V, 2.25MHz Boost LED Driver w/ True Color PWM Dimming
Lifecycle:
New from this manufacturer.
Delivery:
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