FEATURES
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LT3003
3-Channel LED
Ballaster with PWM
DESCRIPTION
The LT
®
3003 drives three separate strings of LEDs up
to 350mA/channel with 3% accurate current matching,
resulting in uniform LED brightness and intensity. This
approach is superior to conventional methods of running
three separate channels with external ballast resistors
requiring expensive factory calibration.
The LT3003 operates in boost, buck and buck-boost mode.
A True Color PWM Dimming ratio of up to 3000:1 is achiev-
able using a logic-level signal at the PWM pin for all modes
without the need for external level-shifting circuitry. For
applications with input supply above and below the output
voltage of the LED strings, the LT3003 allows the LEDs to
be returned to the input supply (buck-boost mode) instead
of being limited to only SEPIC solutions.
The LT3003 is ideal for high power LED driver applications
such as TFT LCD backlighting and heads-up displays. Ad-
ditional overtemperature outputs allow appropriate system
management for increased reliability.
The LT3003 is available in a small 10-pin MSE package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
True Color PWM is a trademark of Linear Technolology Corporation.
All other trademarks are the property of their respective owners.
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3% LED Current Matching
Up to 350mA Continuous Current per LED String
Up to 3000:1 True Color PWM
TM
Dimming Range
PWM Input Disconnects LED Strings
Can Operate in Buck, Boost and Buck-Boost Modes
Wide Input Range: 3V to 40V
Overtemperature Outputs
Works with LT1618, LT3477, LT3474, LT3475,
LT3476, LTC
®
3783
Thermally Enhanced 10-Pin MSOP Package
APPLICATIONS
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High Power LED Ballaster
Automotive Lighting
Video Cameras
TFT LCD Backlighting
TYPICAL APPLICATION
Buck Mode LT3003 with the LT3476
PV
IN
32V
1µF
0.1Ω
Efficiency
90
8
×
3 = 24 LEDs
350mA PER STRING
85
80
75
70
65
0.33µF
LED1
V
MAX
SHDN
PWM
DIMMING
PWM
GND
LED2
LT3003
OT1 OT2
LED3
V
IN
1µF
V
EE
EFFICIENCY (%)
CAP LED
V
IN
3V TO 16V
10µF
V
IN
PWM
V
C
1nF
SW
10µH
60
PV
IN
= 32V
NUMBER OF LEDS = 8
×
3 = 24
0
1000
400
600
800
200
TOTAL LED CURRENT (mA)
1200
SIMPLIFIED LT3476
GND
3003 TA01a
3003 TA01b
3003fa
1
LT3003
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW
LED1
LED2
LED3
V
MAX
V
IN
1
2
3
4
5
10
9
8
7
6
V
EE
SHDN
OT2
OT1
PWM
11
V
IN
............................................................................40V
LED1, LED2, LED3 ....................................................48V
V
MAX
, SHDN ..............................................................48V
V
IN
– V
EE
...................................................................36V
V
EE
............................................................................36V
PWM .........................................................................15V
OT1, OT2.....................................................................6V
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
MSE PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 35°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
ORDER PART NUMBER
LT3003EMSE
MSE PART MARKING
LTCFF
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 specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
PARAMETER
V
IN
Operational Input Voltage
Minimum (V
IN
– V
EE
)
V
IN
Quiescent Current
V
IN
Shutdown Current
V
MAX
Quiescent Current
SHDN Pin Threshold
LED Current Matching
|LED2 – LED1|, |LED2 – LED3| LED Current
Matching with LED Pin Voltage Mismatch
LED Pin Voltage
LED1, LED2, LED3 Maximum Current
LED1, LED2, LED3 Maximum Leakage Current
PWM Switching Threshold
Turn-On Delay (PWM On to I
LED
On)
V
EE
Pin Current in Buck Mode
Overtemperature Sense Point (OT1, OT2)
Overtemperature Hysteresis Point
OT1 Pull-Down Current
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. PWM = 1V, V
MAX
= 4V, V
IN
= 3V, V
EE
= 0V, I
LED2
= 100mA,
OT1 = OT2 = Open, SHDN = V
IN
.
CONDITIONS
V
EE
= 0V, I
LED1,2,3
= 100mA
V
EE
= 4V, I
LED1,2,3
= 100mA
V
EE
= 0V to 36V
PWM = 1V, I
LED1,2,3
= 100mA
PWM = 0V, V
LED1
= V
LED2
= V
LED3
SHDN = 0V, I
LED1,2,3
= 0mA
PWM = 1V, I
LED2
= 100mA
PWM = 0V, V
LED1
= V
LED2
= V
LED3
I
LED2
= 100mA, V
LED1
= V
LED2
= V
LED3
I
LED2
= 350mA, V
LED1
= V
LED2
= V
LED3
I
LED2
= 350mA,
(|V
LED2
– V
LED1
| + |V
LED2
– V
LED3
|) = 700mV
I
LED2
= 100mA
V
LED1,2,3
< 1.5V
PWM = 0V, V
LED1,2,3
= 48V
I
LED1,2,3
= 100mA
PWM = 0V to 1V, I
LED
> 50mA
PWM = 0V, V
MAX
= 40V, V
IN
= 39V, V
EE
= 36V
(Note 4)
(Note 5)
OT1 = 0.3V (Note 4)
●
●
●
MIN
3
TYP
MAX
36
40
UNITS
V
V
V
mA
µA
µA
µA
nA
V
%
%
V
mA
µA
V
µs
µA
°C
°C
µA
2.7
10.5
470
2
4
55
20
0.25
–3
–3.5
0.7
375
0.3
0.7
0
0.5
0.8
500
0.1
0.5
2
0.1
125
–6° from Overtemp
Sense Point
100
3
600
10
90
300
1
+3
+3.5
0.9
550
1
0.7
1
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LT3003
ELECTRICAL CHARACTERISTICS
PARAMETER
OT2 Pull-Down Current
OT1, OT2 Leakage Current
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. PWM = 1V, V
MAX
= 4V, V
IN
= 3V, V
EE
= 0V, I
LED2
= 100mA,
OT1 = OT2 = Open, SHDN = V
IN
.
CONDITIONS
OT2 = 0.3V (Note 4)
OT1 = OT2 = 5V
MIN
300
1
TYP
MAX
UNITS
µA
µA
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:
The LT3003E is guaranteed to meet performance specifications
from 0°C to 85°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls.
Note 3:
This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
Note 4:
Correlation to static test at T
A
= 25°C.
Note 5:
Guaranteed by design.
TYPICAL PERFORMANCE CHARACTERISTICS
I
LED1,3
to I
LED2
Matching
3.0
35
INPUT QUIESCENT CURRENT (mA)
30
25
20
15
10
5
0
125
50
100
150
250
200
I
LED
(mA)
I
LED1,3
– I
LED2
I
LED2
2.5 I
LED2
= 350mA
V
LED1
= V
LED2
= V
LED3
2.0
1.5
1.0
0.5
0
0
50
75 100
25
–50 –25
JUNCTION TEMPERATURE (°C)
T
A
= 25°C unless otherwise noted.
V
EE
Pin Current (Out of the Pin)
vs Temperature
500
450
V
EE
PIN CURRENT • –1 (nA)
400
350
300
250
200
150
100
50
300
350
3003 G02
V
IN
Quiescent Current vs I
LED
T
J
= 27°C
10µs AFTER PWM = 0
I
LED1,3
vs I
LED2
(%)
0
50
25
0
75 100
–50 –25
JUNCTION TEMPERATURE (°C)
125
3003 G01
3003 G03
V
MAX
Pin Current vs Temperature
10
9
8
V
MAX
PIN CURRENT (nA)
7
6
5
4
3
2
1
0
50
25
0
75 100
–50 –25
JUNCTION TEMPERATURE (°C)
125
10µs AFTER PWM = 0
V
IN
SHUTDOWN CURRENT (µA)
7
6
5
4
3
2
1
V
IN
Shutdown Current
vs Temperature
SHDN = 0
1150
1100
(V
LED1,2,3
– V
EE
) (mV)
1050
1000
950
900
850
800
(V
LED1,2,3
– V
EE
) vs I
LED
0
50
100
–50 –25
25
75
0
JUNCTION TEMPERATURE (°C)
125
50
100
150
200
250
300
350
400
I
LED
(mA)
3003 G06
3003 G04
3003 G05
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LT3003
TYPICAL PERFORMANCE CHARACTERISTICS
V
IN
Quiescent Current vs I
LED
35
V
IN
QUIESCENT CURRENT (mA)
V
IN
SHUTDOWN CURRENT (µA)
30
25
20
15
10
5
0
50
100
150
250
200
I
LED
(mA)
300
350
3003 G07
T
A
= 25°C unless otherwise noted.
V
IN
Shutdown Current vs V
IN
16
14
12
10
8
6
4
2
0
3
8
13
23
18
V
IN
(V)
28
33
38
3003 G08
SHDN = 0
PIN FUNCTIONS
LED1 (Pin 1):
Controlled current input for a string of LEDs
with a cathode lead connected to the pin. Connect the first
string of LEDs to this pin.
LED2 (Pin 2):
Controlled current input for a string of LEDs
with a cathode lead connected to the pin. Connect the sec-
ond string of LEDs to this pin.
LED3 (Pin 3):
Controlled current input for a string of LEDs
with a cathode lead connected to the pin. Connect the third
string of LEDs to this pin.
V
MAX
(Pin 4):
• Boost: Connect to V
OUT
• Buck Mode: Connect to Input Supply
• Buck-Boost Mode: Connect to V
OUT
V
IN
(Pin 5):
Input Supply, Upper Rail. This pin must be
locally bypassed with a capacitor to ground. V
IN
powers
the internal control circuitry.
• Boost: Connect to Input Supply
• Buck Mode: Connect to Input Supply
• Buck-Boost Mode: Connect to V
OUT
PWM (Pin 6):
Input Pin for PWM Dimming Control. A
PWM signal above 0.5V (on threshold) turns the LT3003
channels on. A PWM signal below 0.5V completely discon-
nects each LED string. If the application does not require
PWM dimming, then the PWM pin can be left either open
(an internal 10µA source current pulls PWM high) or it
can be connected to a supply between 0.5V to 15V.
OT1 (Pin 7):
Overtemperature Output. OT1 pulls 100µA
from the pin when the junction temperature exceeds
125°C. The part has to cool down by 6°C for the flag to
reset; ideal for providing an overtemperature flag to the
system microprocessor.
OT2 (Pin 8):
Overtemperature Output. OT2 Pulls 300µA
from the pin when the junction temperature exceeds
125°C. The part has to cool down by 6°C for the flag to
reset; ideal for connecting to the switching regulator g
m
error amplifier output to defeat switching.
SHDN (Pin 9):
Micropower Shutdown Pin. Below 0.7V
shuts down the IC. Typically I
VIN
= 4µA for SHDN = 0V.
• Boost: Connect to System Shutdown Signal or V
IN
• Buck Mode: Connect to System Shutdown Signal
or V
IN
• Buck-Boost Mode: If PWM dimming, connect to PWM
(Pin 6); if no PWM dimming, connect to system shut-
down signal or V
IN
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LT3003
PIN FUNCTIONS
V
EE
(Pin 10):
Lower Rail.
• Boost: Connect to System Ground
• Buck Mode: Connect to Inductor
• Buck-Boost Mode: Connect to Input Supply
Exposed Pad (Pin 11):
GND. The ground for the IC should
be soldered to a continuous copper ground plane under
the LT3003 die. Soldering the Exposed Pad to the copper
ground plane under the device will reduce thermal resis-
tance and increase the power capability of the LT3003.
BLOCK DIAGRAM
1
LED1
4
V
MAX
V
IN
2
LED2
3
LED3
B1
+
–
B2
+
–
B3
V
EE
B1 B2 B3
10
PWM
LOGIC
+
–
3V
V
IN
5
V
EE
6
PWM
+
0.5V
+
–
BIAS
BG
THERMAL
SHUTDOWN
BG
125°C
150°C
0.7V
SHDN
9
–
OT1
7
OT2
8
11
EXPOSED PAD
3003 F01
Figure 1. Block Diagram
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