LT3496
Triple Output LED Driver
Features
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Description
The LT
®
3496 is a triple output DC/DC converter designed
to operate as a constant-current source and is ideal for
driving LEDs. The LT3496 works in buck, boost or buck-
boost mode. The LT3496 uses a fixed frequency, current
mode architecture resulting in stable operation over a
wide range of supply and output voltages. A frequency
adjust pin allows the user to program switching frequency
between 330kHz and 2.1MHz to optimize efficiency and
external component size.
The LT3496 supports 3000:1 dimming control on each
channel. Each of the three regulators is independently
operated by that channel’s PWM signal. The PWM feature
allows precise adjustment of the color mixing or dimming
ratio of the LED source. Each of the three channels has
a built-in gate driver to drive an external LED-disconnect
P-channel MOSFET, allowing high dimming range. The
output current range of each channel of the LT3496 is
programmed with an external sense resistor.
The CTRL pins are used to adjust the LED currents either
for analog dimming or overtemperature protection.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT and True Color PWM are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents, including
7199560, 7321203, and others pending.
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True Color PWM™ Dimming Delivers Up to 3000:1
Dimming Ratio
Built-In Gate Driver for PMOS LED Disconnect
Three Independent Driver Channels with 750mA,
45V Internal Switches
Operates in Buck, Boost, Buck-Boost Modes
CTRL Pin Accurately Sets LED Current Sense
Threshold Over a Range of 10mV to 100mV
Adjustable Frequency: 330kHz to 2.1MHz
Open LED Protection
Wide V
IN
Supply Range:
Operation from 3V to 30V
Transient Protection to 40V
Surface Mount Components
28-Lead (4mm
×
5mm) QFN and TSSOP Packages
applications
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RGB Lighting
Billboards and Large Displays
Automotive and Avionic Lighting
Constant-Current Sources
typical application
High Dimming Ratio Triple Output LED Power Supply
PV
IN
42V
CAP1
200m
LED1
TG1
TG2
CAP2
200m
LED2
CAP3
200m
LED3
TG3
PWM
5V/DIV
1µF
3
3000:1 PWM Dimming at 120Hz
7 LEDs
0.5A
0.5A
0.5A
I
L
0.5A/DIV
I
LED
0.5A/DIV
0.5µs/DIV
3496 TA01b
18µH
0.47µF 0.47µF
18µH
18µH
0.47µF
SW1
CAP1, CAP2, CAP3
LED1, LED2, LED3
V
IN
PWM1, PWM2, PWM3
SHDN
SW2
LT3496
GND
V
IN
3V TO 24V
1µF
PWM1, PWM2, PWM3
SHDN
TG1, TG2, TG3
VC1, VC2, VC3
V
REF
CTRL1, CTRL2, CTRL3
f
ADJ
OVP1, OVP2, OVP3
SW3
22k
470pF
3496 TA01a
3496ff
LT3496
absolute MaxiMuM ratings
(Note 1)
V
IN
(Note 4) ...............................................................40V
SW1, SW2, SW3, LED1, LED2, LED3,
CAP1, CAP2, CAP3....................................................45V
TG1, TG2, TG3.................................... CAP – 10V to CAP
PWM1, PWM2, PWM3..............................................20V
V
REF
, CTRL1, CTRL2, CTRL3, f
ADJ
, VC1, VC2, VC3,
OVP1, OVP2, OVP3 ..................................................2.5V
SHDN
(Note 4) ...........................................................V
IN
Operating Junction Temperature Range (Notes 2, 6)
LT3496E ............................................ –40°C to 125°C
LT3496I ............................................. –40°C to 125°C
LT3496H ............................................ –40°C to 150°C
Storage Temperature Range
QFN.................................................... –65°C to 150°C
TSSOP ................................................. 65°C to 125°C
Lead Temperature (Soldering, 10 sec)
TSSOP .............................................................. 300°C
pin conFiguration
TOP VIEW
SHDN
PWM3
PWM2
PWM1
V
REF
CTRL3
CTRL2
CTRL1
f
ADJ
1
2
3
4
5
6
7
8
9
29
28 V
IN
PWM2
27 TG3
26 LED3
25 CAP3
24 SW3
23 SW2
22 CAP2
21 LED2
20 TG2
19 SW1
18 CAP1
17 LED1
16 TG1
15 OVP1
PWM1 1
V
REF
2
CTRL3 3
CTRL2 4
CTRL1 5
f
ADJ
6
VC3 7
VC2 8
9 10 11 12 13 14
VC1
OVP3
OVP2
OVP1
TG1
LED1
29
TOP VIEW
PWM3
SHDN
LED3
22 CAP3
21 SW3
20 SW2
19 CAP2
18 LED2
17 TG2
16 SW1
15 CAP1
TG3
V
IN
28 27 26 25 24 23
VC3 10
VC2 11
VC1 12
OVP3 13
OVP2 14
FE PACKAGE
28-LEAD PLASTIC TSSOP
θ
JA
= 30°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
UFD PACKAGE
28-LEAD (4mm 5mm) PLASTIC QFN
θ
JA
= 34°C/W,
θ
JC
= 2.7°C/W
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
orDer inForMation
LEAD FREE FINISH
LT3496EFE#PBF
LT3496IFE#PBF
LT3496EUFD#PBF
LT3496IUFD#PBF
LT3496HUFD#PBF
TAPE AND REEL
LT3496EFE#TRPBF
LT3496IFE#TRPBF
LT3496EUFD#TRPBF
LT3496IUFD#TRPBF
LT3496HUFD#TRPBF
PART MARKING*
3496FE
3496FE
3496
3496
3496
PACKAGE DESCRIPTION
28-Lead Plastic TSSOP
28-Lead Plastic TSSOP
28-Lead (4mm
×
5mm) Plastic QFN
28-Lead (4mm
×
5mm) Plastic QFN
28-Lead (4mm
×
5mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
*For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
3496ff
LT3496
electrical characteristics
PARAMETER
V
IN
Operation Voltage
V
IN
Undervoltage Lockout
Full-Scale LED Current Sense Voltage
(V
CAP1-LED1
, V
CAP2-LED2
, V
CAP3-LED3
)
One-Tenth Scale LED Current Sense Voltage
(V
CAP1-LED1
, V
CAP2-LED2
, V
CAP3-LED3
)
CAP1, CAP2, CAP3 Operating Voltage
CAP1, CAP2, CAP3 = 24V
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 5V, V
SHDN
= 5V, CAP1, CAP2, CAP3 = 5V, PWM1, PWM2, PWM3 = 5V,
f
ADJ
= 0.5V, CTRL1, CTRL2, CTRL3 = 1.5V, OVP1, OVP2, OVP3 = 0V, unless otherwise noted.
CONDITIONS
(Note 4)
MIN
3
2.1
98
97
7.5
7.5
2.5
100
TYP
MAX
30
2.4
103
104
13.5
12.5
45
UNITS
V
V
mV
mV
mV
mV
V
CTRL1, CTRL2, CTRL3 = 100mV, CAP1, CAP2, CAP3 = 24V
H-Grade
E-Grade, I-Grade
0V ≤ V
CAP1-LED1
≤ 104mV
0V ≤ V
CAP2-LED2
≤ 104mV
0V ≤ V
CAP3-LED3
≤ 104mV
I
REF
= 200µA, Current Out of Pin
3V ≤ V
IN
≤ 40V, I
REF
= 10µA
SHDN
= 0V
PWM1, PWM2, PWM3 = 0V
f
ADJ
= 1.5V
f
ADJ
= 0.5V
f
ADJ
= 0.1V
f
ADJ
= 1.5V (2.1MHz)
f
ADJ
= 0.5V (1.3MHz)
f
ADJ
= 0.1V (330kHz)
Current Out of Pin, CTRL1, CTRL2, CTRL3 = 0.1V
Current Out of Pin, f
ADJ
= 0.1V
Current Out of Pin, OVP1, OVP2, OVP3 = 0.1V
l
l
10
10
V
REF
Output Voltage
V
REF
Line Regulation
Quiescent Current in Shutdown
Quiescent Current Idle
Quiescent Current Active (Not Switching)
Switching Frequency
l
1.96
2
0.1
6
11
2.04
0.03
10
7.5
14
2300
V
%/V
µA
mA
mA
kHz
kHz
kHz
%
%
%
1900
2100
1300
330
78
87
97
20
20
10
Maximum Duty Cycle
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70
CTRL1, CTRL2, CTRL3 Input Bias Current
f
ADJ
Input Bias Current
OVP1, OVP2, OVP3 Input Bias Current
OVP1, OVP2, OVP3 Threshold
VC1, VC2, VC3 Idle Input Bias Current
VC1, VC2, VC3 Output Impedance
EAMP g
m
(ΔI
VC
/ΔV
CAP-LED
)
SW1, SW2, SW3 Current Limit
SW1, SW2, SW3 V
CESAT
SW1, SW2, SW3 Leakage Current
CAP1, CAP2, CAP3 Input Bias Current
CAP1, CAP2, CAP3, LED1, LED2, LED3 Idle Input
Bias Current
CAP1, CAP2, CAP3, LED1, LED2, LED3 Input Bias
Current in Shutdown
100
100
100
1.05
20
nA
nA
nA
V
nA
MΩ
µS
0.95
PWM1, PWM2, PWM3 = 0V
CAP1, CAP2, CAP3 = 24V
CAP1, CAP2, CAP3 = 24V
(Note 3)
I
SW
= 500mA (Note 3)
SHDN
= 0V, SW = 5V
750
–20
1
0
10
200
1000
260
1250
2
mA
mV
µA
µA
µA
µA
180
PWM1, PWM2, PWM3 = 0V
SHDN
= 0V
250
1
1
3496ff
LT3496
electrical characteristics
PARAMETER
SHDN
Input Low Voltage
SHDN
Input High Voltage
SHDN
Pin Current
PWM1, PWM2, PWM3 Input Low Voltage
PWM1, PWM2, PWM3 Input High Voltage
PWM1, PWM2, PWM3 Pin Current
Gate Off Voltage
(CAP1 – TG1, CAP2 – TG2, CAP3 – TG3)
Gate On Voltage
(CAP1 – TG1, CAP2 – TG2, CAP3 – TG3)
Gate Turn-On Delay
Gate Turn-Off Delay
Current Into Pin
CAP1, CAP2, CAP3 = 40V,
PWM1, PWM2, PWM3 = 0V
CAP1, CAP2, CAP3 = 40V
,
C
LOAD
= 300pF CAP1, CAP2, CAP3 = 40V (Note 5)
,
C
LOAD
= 300pF CAP1, CAP2, CAP3 = 40V (Note 5)
5.5
1.2
160
0.1
6.5
110
110
210
0.3
7.5
V
SHDN
= 5V, Current Into Pin
1.5
65
100
0.4
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 5V, V
SHDN
= 5V, CAP1, CAP2, CAP3 = 5V, PWM1, PWM2, PWM3 = 5V,
f
ADJ
= 0.5V, CTRL1, CTRL2, CTRL3 = 1.5V, OVP1, OVP2, OVP3 = 0V, unless otherwise noted.
CONDITIONS
MIN
TYP
MAX
0.4
UNITS
V
V
µA
V
V
µA
V
V
ns
ns
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 LT3496E is guaranteed to meet performance specifications
from 0°C to 125°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. The
LT3496I is guaranteed over the full –40°C to 125°C operating junction
temperature range. The LT3496H is guaranteed over the full –40°C to
150°C operating junction temperature range. High junction temperatures
degrade operating lifetimes. Operating lifetime is derated at junction
temperatures greater than 125°C.
Note 3:
Current flows into pin. Current limit and switch V
CESAT
is
guaranteed by design and/or correlation to static test.
Note 4:
Absolute maximum voltage at the V
IN
and
SHDN
pins is 40V for
nonrepetitive 1 second transients, and 30V for continuous operation.
Note 5:
Gate turn-on/turn-off delay is measured from 50% level of PWM
voltage to 90% level of gate on/off voltage.
Note 6:
The LT3496 includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed the maximum operating junction temperature
when overtemperature protection is active. Continuous operating above
the specified maximum operating junction temperature may impair device
reliability.
3496ff
LT3496
typical perForMance characteristics
Quiescent Current
14
12
INPUT CURRENT (mA)
10
8
6
4
2
0
V
C
= GND, NOT SWITCHING
0
10
20
V
IN
(V)
3496 G01
(T
A
= 25°C unless otherwise noted)
Switch Current Limit
vs Duty Cycle
1000
Switch On Voltage
500
PWM1, PWM2, PWM3 = 5V
400
SWITCH VOLTAGE (mV)
SWITCH CURRENT LIMIT (mA)
800
300
600
PWM1, PWM2, PWM3 = 0V
200
100
400
200
30
40
0
0
200
600
800
400
SWITCH CURRENT (mA)
1000
3496 G02
0
0
20
60
40
DUTY CYCLE (%)
80
100
3496 G03
Switch Current Limit vs
Temperature
1200
1000
CURRENT LIMIT (mA)
800
V
REF
(V)
600
400
200
0
–50 –25
2.04
2.03
Reference Voltage
vs Temperature
2250
2000
SWITCH FREQUENCY (kHz)
1750
Switch Frequency vs f
ADJ
2.02
2.01
2.00
1.99
1.98
1.97
0
25 50 75 100 125 150
TEMPERATURE (°C)
3496 G04
1500
1250
1000
750
500
250
1.96
–50 –25
0
25 50 75 100 125 150
TEMPERATURE (°C)
3496 G05
0
0
0.2
0.4
0.6
f
ADJ
(V)
0.8
1.0
1.2
3496 G06
3496ff
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