LT3492 - Triple Output LED Driver with 3000:1 PWM Dimming

LT3492
Triple Output LED Driver
with 3000:1 PWM Dimming
DESCRIPTION
FEATURES
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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 600mA,
60V 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 Input Voltage 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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The LT®3492 is a triple output DC/DC converter designed
to operate as a constant-current source and is ideal for
driving LEDs. The LT3492 works in buck, boost or buckboost mode. The LT3492 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 external PWM input provides 3000:1 LED dimming
on each channel. 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 LT3492 is programmed with
an external sense resistor.
The CTRL pin is used to adjust the LED current either for
analog dimming or overtemperature protection.
RGB Lighting
Billboards and Large Displays
Automotive and Avionic Lighting
Constant-Current Sources
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. True Color PWM is a trademark 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.
TYPICAL APPLICATION
High Dimming Ratio Triple Output Buck-Mode LED Power Supply
PVIN
58V
ISP1
ISP2
ISP3
330mΩ
330mΩ
330mΩ
ISN2
ISN3
ISN1
TG1
1μF
s3
3000:1 PWM Dimming at 100Hz
TG3
TG2
PWM
5V/DIV
10 LEDs
0.3A
0.3A
0.3A
0.47μF 0.47μF
33μH
ILED
0.2A/DIV
0.47μF
33μH
IL
0.5A/DIV
33μH
1μs/DIV
VIN
3V TO 24V
1μF
SW1
ISP1-3
ISN1-3
VIN
PWM1-3
SHDN
SW2
SW3
3492 TA01b
TG1-3
VC1-3
VREF
CTRL1-3
150k
LT3492
10k
FADJ
49.9k
680pF
1.3MHz
GND
OVP1-3
3492 TA01a
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LT3492
ABSOLUTE MAXIMUM RATINGS
(Note 1)
VIN (Note 4) ...............................................................40V
SW1-SW3, ISN1-ISN3, ISP1-ISP3 ............................60V
TG1-TG3 ...............................................ISP – 10V to ISP
PWM1-PWM3 ...........................................................20V
VREF, CTRL1-CTRL3, FADJ, VC1-VC3, OVP1-OVP3....2.5V
SHDN (Note 4) ...........................................................VIN
Operating Junction Temperature Range
(Note 2).................................................. –40°C to 125°C
Max Junction Temperature.................................... 125°C
Storage Temperature Range
TSSOP ............................................... –65°C to 150°C
UFD.................................................... –65°C to 125°C
PIN CONFIGURATION
TOP VIEW
SHDN
1
28 VIN
PWM3
2
27 TG3
PWM2
3
26 ISN3
PWM1
4
25 ISP3
VREF
5
24 SW3
CTRL3
6
23 SW2
CTRL3 3
CTRL2
7
22 ISP2
CTRL2 4
CTRL1
8
21 ISN2
CTRL1 5
FADJ
9
20 TG2
FADJ 6
17 TG2
VC3 10
19 SW1
VC3 7
16 SW1
VC2 11
18 ISP1
VC2 8
VC1 12
17 ISN1
ISN3
TG3
VIN
SHDN
PWM3
PWM2
20 SW2
19 ISP2
GND
29
18 ISN2
15 ISP1
FE PACKAGE
28-LEAD PLASTIC TSSOP
TJMAX = 125°C, θJA = 30°C/W, θJC = 10°C/W
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
ISN1
TG1
9 10 11 12 13 14
OVP1
15 OVP1
21 SW3
OVP2
16 TG1
OVP2 14
22 ISP3
VREF 2
VC1
OVP3 13
28 27 26 25 24 23
PWM1 1
OVP3
GND
29
TOP VIEW
UFD PACKAGE
28-LEAD (4mm s 5mm) PLASTIC QFN
TJMAX = 125°C, θJA = 34°C/W, θJC = 2.7°C/W
EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT3492EFE#PBF
LT3492EFE#TRPBF
LT3492FE
28-Lead Plastic TSSOP
–40°C to 125°C
LT3492IFE#PBF
LT3492IFE#TRPBF
LT3492FE
28-Lead Plastic TSSOP
–40°C to 125°C
LT3492EUFD#PBF
LT3492EUFD#TRPBF
3492
28-Lead (4mm × 5mm) Plastic QFN
–40°C to 125°C
LT3492IUFD#PBF
LT3492IUFD#TRPBF
3492
28-Lead (4mm × 5mm) Plastic QFN
–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.
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/
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LT3492
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 5V, SHDN = 5V, PWM1-3 = 5V, FADJ = 0.5V, CTRL1-3 = 1.5V,
OVP1-3 = 0V, unless otherwise noted.
PARAMETER
CONDITIONS
VIN Operation Voltage
(Note 4)
MIN
ISP1-3 = 48V
One-Tenth Scale LED Current Sense Voltage
CTRL1-3 = 100mV, ISP1-3 = 48V
l
ISPn/ISNn Operating Voltage
VREF Output Voltage
VREF Line Regulation
3V ≤ VIN ≤ 40V, IREF = 10μA
Quiescent Current in Shutdown
SHDN = 0V
Quiescent Current Idle
l
UNITS
V
2.1
2.4
V
98
96
100
103
104
mV
mV
7
10
13
mV
60
V
2.04
V
2.5
IREF = 200μA, Current Out of Pin
MAX
30
VIN Undervoltage Lockout
Full-Scale LED Current Sense Voltage
TYP
3
1.96
2
0.03
%/V
0.1
10
μA
PWM1-PWM3 = 0V
6
8
mA
Quiescent Current Active (Not Switching)
VC1-VC3 = 0V
11
15
mA
Switching Frequency
FADJ = 1.5V
FADJ = 0.5V
FADJ = 0.1V
1800
1000
280
2100
1300
340
2400
1600
400
kHz
kHz
kHz
Maximum Duty Cycle
FADJ = 1.5V (2.1MHz)
FADJ = 0.5V (1.3MHz)
FADJ = 0.1V (330kHz)
73
80
78
87
97
CTRL1-3 Input Bias Current
Current Out of Pin, CTRL1-3 = 0.1V
20
100
nA
FADJ Input Bias Current
Current Out of Pin, FADJ = 0.1V
20
100
nA
OVP1-3 Input Bias Current
Current Out of Pin, OVP1-3 = 0.1V
OVP1-3 Threshold
%
%
%
10
100
nA
0.95
1
1.05
V
–20
0
20
nA
VC1-3 Idle Input Bias Current
PWM1-3 = 0V
VC1-3 Output Impedance
ISP1-3 = 48V
10
MΩ
EAMP gm (ΔIVC/ΔVCAP-LED)
ISP1-3 = 48V
200
μS
SW1-3 Current Limit
(Note 3)
SW1-3 VCESAT
ISW = 500mA (Note 3)
SW1-3 Leakage Current
SHDN = 0V, SW = 5V
600
1000
1300
340
mA
mV
2
μA
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LT3492
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 5V, SHDN = 5V, PWM1-3 = 5V, FADJ = 0.5V, CTRL1-3 = 1.5V,
OVP1-3 = 0V, unless otherwise noted.
PARAMETER
CONDITIONS
MIN
ISP1-3 Input Bias Current
TYP
MAX
UNITS
180
250
μA
ISP1-3, ISN1-3 Idle Input Bias Current
PWM1-3 = 0V
1
μA
ISP1-3, ISN1-3 Input Bias Current in Shutdown
SHDN = 0V
1
μA
0.4
V
SHDN Input Low Voltage
SHDN Input High Voltage
SHDN Pin Current
1.5
SHDN = 5V, Current Into Pin
V
65
PWM1-3 Input Low Voltage
120
μA
0.4
PWM1-3 Input High Voltage
V
1.2
V
PWM1-3 Pin Current
Current Into Pin
160
210
μA
Gate Off Voltage (ISP1-3–TG1-3)
ISP1-3 = 60V, PWM1-3 = 0V
0.1
0.3
V
Gate On Voltage (ISP1-3–TG1-3)
ISP1-3 = 60V
6.5
7.5
V
Gate Turn-On Delay
CLOAD = 300pF, ISP1-3 = 60V (Note 5)
110
ns
Gate Turn-Off Delay
CLOAD = 300pF, ISP1-3 = 60V (Note 5)
110
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 LT3492E 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
LT3492I is guaranteed over the full –40°C to 125°C operating junction
temperature range.
5.5
Note 3: Current flows into pin. Current limit and switch VCESAT is
guaranteed by design and/or correlation to static test.
Note 4: Absolute maximum voltage at the VIN 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.
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LT3492
TYPICAL PERFORMANCE CHARACTERISTICS
Quiescent Current
600
1200
500
1000
10
8
PWM1-3 = 0V
6
4
SWITCH CURRENT LIMIT (mA)
SWITCH VOLTAGE (mV)
PWM1-3 = 5V
12
INPUT CURRENT (mA)
Switch Current Limit
vs Duty Cycle
Switch On Voltage
14
400
300
200
100
2
VC = GND, NOT SWITCHING
0
0
10
20
0
40
30
0
200
VIN (V)
600
800
400
SWITCH CURRENT (mA)
Switch Current Limit vs
Temperature
400
200
0
1000
2250
2.03
2000
VREF (V)
1.97
125
3492 G04
100
1750
1000
1.98
100
80
1250
2.00
1.99
200
60
40
DUTY CYCLE (%)
1500
2.01
400
20
Switch Frequency vs FADJ
2.04
2.02
800
600
0
3492 G03
SWITCH FREQUENCY (kHz)
1000
50
25
75
0
TEMPERATURE (°C)
600
Reference Voltage
vs Temperature
1200
0
–50 –25
800
3492 G02
3492 G01
CURRENT LIMIT (mA)
(TA = 25°C unless otherwise noted)
1.96
–50 –25
750
500
250
75
50
25
TEMPERATURE (°C)
0
100
125
3492 G05
0
0
0.2
0.4
0.6
0.8
FADJ (V)
1.0
1.2
3492 G06
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LT3492
TYPICAL PERFORMANCE CHARACTERISTICS
Switch Frequency vs Temperature
VISP-VISN Threshold vs VISP
VISP-VISN Threshold vs CTRL
120
1.4
103
VISP = 24V
1.3
1.2
1.1
100
VISP-VISN TRHESHOLD (mV)
VISP-VISN THRESHOLD (mV)
FADJ = 0.5V
SWITCH FREQUENCY (MHz)
(TA = 25°C unless otherwise noted)
80
60
40
20
1.0
–50 –25
0
50
25
75
0
TEMPERATURE (°C)
100
125
VISP-VISN THRESHOLD (mV)
101
100
99
0
0.2
0.4
0.6
0.8
CTRL (V)
1
1.2
97
0
10
20
30
VISP (V)
40
3492 G08
VISP-VISN Threshold vs
Temperature
102
102
98
3492 G07
103
CTRL = 1.2V
50
60
3492 G09
PMOS Turn On Waveforms
PMOS Turn Off Waveforms
CTRL = 1.2V
VISP = 24V
5V
5V
PWM
101
PWM
0V
0V
100
60V
99
60V
TG
TG
50V
50V
98
97
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
3492 G10
VISP = 60V
QG FET = 6nC
200ns/DIV
3492 G11
VISP = 60V
QG FET = 6nC
200ns/DIV
3492 G12
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LT3492
PIN FUNCTIONS
CTRL1, CTRL2, CTRL3: LED Current Adjustment Pins. Sets
voltage across external sense resistor between ISP and ISN
pins of the respective converter. Setting CTRL voltage to
be less than 1V will control the current sense voltage to be
one-tenth of CTRL voltage. If CTRL voltage is higher than
1V, the default current sense voltage is 100mV. The CTRL
pin must not be left floating.
quiescent supply current and causes the VC pin for that
converter to become high impedance. PWM pin must not
be left floating; tie to VREF if not used.
FADJ: Switching Frequency Adjustment Pin. Setting FADJ
voltage to be less than 1V will adjust switching frequency
up to 2.1MHz. If FADJ voltage is higher than 1V, the default
switching frequency is 2.1MHz. The FADJ pin must not
be left floating.
SW1, SW2, SW3: Switch Pins. Collector of the internal
NPN power switch of the respective converter. Connect
to external inductor and anode of external Schottky rectifier of the respective converter. Minimize the metal trace
area connected to this pin to minimize electromagnetic
interference.
GND: Signal Ground and Power Ground. Solder exposed
pad directly to ground plane.
ISN1, ISN2, ISN3: Noninverting Input of Current Sense
Error Amplifier. Connect directly to LED current sense
resistor terminal for current sensing of the respective
converter.
ISP1, ISP2, ISP3: Inverting Input of Current Sense Error
Amplifier. Connect directly to other terminal of LED current
sense resistor terminal of the respective converter.
OVP1, OVP2, OVP3: Open LED Protection Pins. A voltage
higher than 1V on OVP turns off the internal main switch
of the respective converter. Tie to ground if not used.
PWM1, PWM2, PWM3: Pulse Width Modulated Input.
Signal low turns off the respective converter, reduces
SHDN: Shutdown Pin. Used to shut down the switching
regulator and the internal bias circuits for all three converters. Tie to 1.5V or greater to enable the device. Tie below
0.4V to turn off the device.
TG1, TG2, TG3: The Gate Driver Output Pin for Disconnect P-Channel MOSFET. One for each converter. When
the PWM pin is low, the TG pin pulls up to ISP to turn
off the external MOSFET. When the PWM pin is high, the
external MOSFET turns on. ISPn-TGn is limited to 6.5V to
protect the MOSFET. Leave open if the external MOSFET
is not used.
VC1, VC2, VC3: Error Amplifier Compensation Pins. Connect
a series RC from these pins to GND.
VIN: Input Supply Pin. Must be locally bypassed. Powers
the internal control circuitry.
VREF: Reference Output Pin. Can supply up to 200μA. The
nominal Output Voltage is 2V.
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LT3492
BLOCK DIAGRAM
D1
VSENSE
+
–
C2
LED ARRAY
ILED
L1
M1
VIN
C1
RSENSE
ISP1
ISN1
TG1
PWM1
SW1
A7
R3
OVP1
MOSFET
DRIVER
VC1
R4
–
RC
+
PWM1
CC
EAMP
+
V1
A1
–
1V
+
NPN
DRIVER
A6
–
A5
A4
Q1
R1 2k
VIN
1V
CTRL1
+
+
–
VC
SR LATCH
–
A3
A8
Q3
+
CTRL
BUFFER
R
A2
PWM
COMPARATOR
SLOPE
Q
S
ISENSE
+
A10
R2
20k
–
GND
REPLICATED FOR EACH CHANNEL
VIN
VIN
C3
SHDN
INTERNAL
REGULATOR
AND UVLO
VIN
200μA
VREF
RAMP
GENERATOR
–
2V
REFERENCE
+
A9
Q2
OSCILLATOR
FADJ
SHARED COMPONENTS
R5
C4
3492 BD
R6
Figure 1. LT3492 Block Diagram Working in Boost Configuration
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LT3492
APPLICATIONS INFORMATION
Operation
The LT3492 uses a fixed frequency, current mode control
scheme to provide excellent line and load regulation. Operation can be best understood by referring to the Block
Diagram in Figure 1. The oscillator, ramp generator, reference, internal regulator and UVLO are shared among the
three converters. The control circuitry, power switch etc.,
are replicated for each of the three converters. Figure 1
shows the shared circuits and only converter 1 circuits.
If the SHDN pin is logic low, the LT3492 is shut down
and draws minimal current from VIN. If the SHDN pin is
logic high, the internal bias circuits turn on. The switching
regulators start to operate when their respective PWM
signal goes high.
The main control loop can be understood by following
the operation of converter 1. The start of each oscillator
cycle sets the SR latch, A3, and turns on power switch
Q1. The signal at the noninverting input (SLOPE node)
of the PWM comparator A2 is proportional to the sum
of the switch current and oscillator ramp. When SLOPE
exceeds VC (the output of the error amplifier A1), A2 resets
the latch and turns off the power switch Q1 through A4
and A5. In this manner, A10 and A2 set the correct peak
current level to keep the output in regulation. Amplifier
A8 has two noninverting inputs, one from the 1V internal
voltage reference and the other one from the CTRL1 pin.
Whichever input is lower takes precedence. A8, Q3 and R2
force V1, the voltage across R1, to be one tenth of either
1V or the voltage of CTRL1 pin, whichever is lower. VSENSE
is the voltage across the sensing resistor, RSENSE, which is
connected in series with the LEDs. VSENSE is compared to
V1 by A1. If VSENSE is higher than V1, the output of A1 will
decrease, thus reducing the amount of current delivered to
LEDs. In this manner the current sensing voltage VSENSE
is regulated to V1.
Converters 2 and 3 are identical to converter 1.
PWM Dimming Control
The LED array can be dimmed with pulse width modulation
using the PWM1 pin and an external P-channel MOSFET,
M1. If the PWM1 pin is pulled high, M1 is turned on by
internal driver A7 and converter 1 operates nominally.
A7 limits ISP1-TG1 to 6.5V to protect the gate of M1. If
the PWM1 pin is pulled low, Q1 is turned off. Converter 1
stops operating, M1 is turned off, disconnects the LED
array and stops current draw from output capacitor C2. The
VC1 pin is also disconnected from the internal circuitry and
draws minimal current from the compensation capacitor
CC. The VC1 pin and the output capacitor store the state
of the LED current until PWM1 is pulled up again. This
leads to a highly linear relationship between pulse width
and output light, and allows for a large and accurate dimming range. A P-channel MOSFET with smaller total gate
charge (QG) improves the dimming performance, since
it can be turned on and off faster. Use a MOSFET with a
QG lower than 10nC, and a minimum VTH of –1V to –2V.
Don’t use a Low VTH PMOS. To optimize the PWM control
of all the three channels, the rising edge of all the three
PWM signals should be synchronized.
In the applications where high dimming ratio is not required,
M1 can be omitted to reduce cost. In these conditions,
TG1 should be left open. The PWM dimming range can be
further increased by using CTRL1 pin to linearly adjust the
current sense threshold during the PWM1 high state.
Loop Compensation
Loop compensation determines the stability and transient
performance. The LT3492 uses current mode control to
regulate the output, which simplifies loop compensation.
To compensate the feedback loop of the LT3492, a series
resistor-capacitor network should be connected from the
VC pin to GND. For most applications, the compensation
capacitor should be in the range of 100pF to 2.2nF. The compensation resistor is usually in the range of 5k to 50k.
To obtain the best performance, tradeoffs should be made
in the compensation network design. A higher value of
compensation capacitor improves the stability and dimming range (a larger capacitance helps hold the VC voltage
when the PWM signal is low). However, a large compensation capacitor also increases the start-up time and the
time to recover from a fault condition. Similarly, a larger
compensation resistor improves the transient response
but may reduce the phase margin. A practical approach
is to start with one of the circuits in this data sheet that
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LT3492
APPLICATIONS INFORMATION
is similar to your application and tune the compensation
network to optimize the performance. The stability, PWM
dimming waveforms and the start-up time should be
checked across all operating conditions.
Open-LED Protection
Input Capacitor Selection
For proper operation, it is necessary to place a bypass
capacitor to GND close to the VIN pin of the LT3492. A
1μF or greater capacitor with low ESR should be used. A
ceramic capacitor is usually the best choice.
The LT3492 has open-LED protection for all the three
converters. As shown in Figure 1, the OVP1 pin receives
the output voltage (the voltage across the output capacitor)
feedback signal from an external resistor divider. OVP1
voltage is compared with a 1V internal voltage reference by
comparator A6. In the event the LED string is disconnected
or fails open, converter 1 output voltage will increase, causing OVP1 voltage to increase. When OVP1 voltage exceeds
1V, the power switch Q1 will turn off, and cause the output
voltage to decrease. Eventually, OVP1 will be regulated to
1V and the output voltage will be limited. In the event one
of the converters has an open-LED protection, the other
converters will continue functioning properly.
In the buck mode configuration, the capacitor at PVIN has
large pulsed currents due to the current returned though
the Schottky diode when the switch is off. For the best
reliability, this capacitor should have low ESR and ESL
and have an adequate ripple current rating. The RMS
input current is:
Switching Frequency and Soft-Start
The selection of output filter capacitor depends on the load
and converter configuration, i.e., step-up or step-down.
For LED applications, the equivalent resistance of the LED
is typically low, and the output filter capacitor should be
large enough to attenuate the current ripple.
The LT3492 switching frequency is controlled by FADJ
pin voltage. Setting FADJ voltage to be less than 1V will
reduce switching frequency.
If FADJ voltage is higher than 1V, the default switching frequency is 2.1MHz. In general, a lower switching
frequency should be used where either very high or very
low switch duty cycle is required or higher efficiency is
desired. Selection of a higher switching frequency will
allow use of low value external components and yield a
smaller solution size and profile.
As a cautionary note, operation of the LT3492 at a combination of high switching frequency with high output
voltage and high switch current may cause excessive
internal power dissipation. Consideration should be given
to selecting a switching frequency less than 1MHz if these
conditions exist.
Connecting FADJ pin to a lowpass filter (R5 and C4 in
Figure 1) from the REF pin provides a soft-start function.
During start-up, FADJ voltage increases slowly from 0V
to the setting voltage. As a result, the switching frequency
increases slowly to the setting frequency. This function
limits the inrush current during start-up.
IIN(RMS) =ILED •
(1– D) • D
where D is the switch duty cycle. A 1μF ceramic type capacitor placed close to the Schottky diode and the ground
plane is usually sufficient for each channel.
Output Capacitor Selection
To achieve the same LED ripple current, the required filter
capacitor value is larger in the boost and buck-boost mode
applications than that in the buck mode applications. For
the LED buck mode applications at 1.3MHz, a 0.22μF ceramic capacitor is usually sufficient for each channel. For
the LED boost and buck-boost applications at 1.3MHz, a
1μF ceramic capacitor is usually sufficient for each channel. Lower switching frequency requires proportionately
higher capacitor values. If higher LED current ripple can
be tolerated, a lower output capacitance can be selected
to reduce the capacitor’s cost and size.
Use only ceramic capacitors with X7R or X5R dielectric,
as they are good for temperature and DC bias stability of
the capacitor value. All ceramic capacitors exhibit loss of
capacitance value with increasing DC voltage bias, so it
may be necessary to choose a higher value capacitor to get
the required capacitance at the operation voltage. Always
check that the voltage rating of the capacitor is sufficient.
Table 1 shows some recommended capacitor vendors.
3492fa
10
LT3492
APPLICATIONS INFORMATION
Table 2. Surface Mount Inductors
Table 1. Ceramic Capacitor Manufacturers
VENDOR
TYPE
SERIES
Taiyo Yuden
Ceramic
X5R, X7R
AVX
Ceramic
X5R, X7R
Murata
Ceramic
X5R, X7R
Kemet
Ceramic
X5R, X7R
TDK
Ceramic
X5R, X7R
Inductor Selection
Inductor value is selected based on switching frequency
and desired transient response. The data sheet applications show appropriate selections for a 1.3MHz switching
frequency. Proportionately higher values may be used if a
lower switching frequency is selected.
Several inductors that work well with the LT3492 are listed
in Table 2. However, there are many other manufacturers
and devices that can be used. Consult each manufacturer
for more detailed information and their entire range of
parts. Ferrite core inductors should be used to obtain the
best efficiency. Choose an inductor that can handle the
necessary peak current without saturating, and ensure that
the inductor has a low DCR (copper-wire resistance) to
minimize I2R power losses. An inductor with a magnetic
shield should be used to prevent noise radiation and cross
coupling among the three channels.
Diode Selection
The Schottky diode conducts current during the interval
when the switch is turned off. Select a diode VR rated
for the maximum SW voltage. It is not necessary that
the forward current rating of the diode equal the switch
current limit. The average current, IF , through the diode
is a function of the switch duty cycle. Select a diode with
forward current rating of:
IF = IL • (1 – D)
where IL is the inductor current.
If using the PWM feature for dimming, it is important to
consider diode leakage, which increases with the temperature from the output during the PWM low interval.
Therefore, choose the Schottky diode with sufficient low
leakage current at hot temperature. Table 3 shows several
Schottky diodes that work well with the LT3492.
PART NUMBER
Sumida
CDRH4D28
CDRH5D28
CooperET
SD20
SD25
Taiyo Yuden
NP04SZB
TDK
VLF5014A
VALUE
(μH)
DCR
(Ω MAX)
IRMS (A)
SIZE
W × L × H (mm3)
15
0.149
0.76
5.0 × 5.0 × 3.0
22
33
0.122
0.189
0.9
0.75
6.0 × 6.0 × 3.0
15
22
33
0.1655
0.2053
0.2149
1.25
1.12
1.11
5.0 × 5.0 × 2.0
15
22
0.180
0.210
0.95
0.77
4.0 × 4.0 × 1.8
15
0.32
0.97
4.5 × 4.7 × 1.4
5.0 × 5.0 × 2.5
22
0.46
0.51
Würth Electronics
7447789133
33
0.24
1.22
7.3 × 7.3 × 3.2
Coilcraft
M556132
22
0.19
1.45
6.1 × 6.1 × 3.2
Table 3. Schottky Diodes
PART NUMBER
VR (V)
IF (A)
PACKAGE
ZLLS350
40
0.38
SOD523
ZLLS400
40
0.52
SOD323
100
1.0
SMA
60
1.0
PMDU/SOD-123
ZETEX
DIODES
B1100
ROHM
RB160M-60
Undervoltage Lockout
The LT3492 has an undervoltage lockout circuit that
shuts down all the three converters when the input voltage drops below 2.1V. This prevents the converter from
switching in an erratic mode when powered from a low
supply voltage.
Programming the LED Current
An important consideration when using a switch with a
fixed current limit is whether the regulator will be able to
supply the load at the extremes of input and output voltage
range. Several equations are provided to help determine
3492fa
11
LT3492
APPLICATIONS INFORMATION
this capability. Some margin to data sheet limits is included,
along with provision for 200mA inductor ripple current.
For boost mode converters:
IOUT(MAX) ≅ 0.4A
VIN(MIN)
VOUT(MAX)
For buck mode converters:
ILED(MAX) ≅ 0.4A
For SEPIC and buck-boost mode converters:
IOUT(MAX) ≅ 0.4A
VIN(MIN)
(VOUT(MAX) + VIN(MIN) )
If some level of analog dimming is acceptable at minimum
supply levels, then the CTRL pin can be used with a resistor
divider to VIN (as shown in the Block Diagram) to provide
a higher output current at nominal VIN levels.
The LED current of each channel is programmed by connecting an external sense resistor RSENSE in series with
the LED load, and setting the voltage regulation threshold
across that sense resistor using CTRL input. If the CTRL
voltage, VCTRL, is less than 1V, the LED current is:
ILED =
VCTRL
10 • RSENSE
If VCTRL is higher than 1V, the LED current is:
ILED =
100mV
RSENSE
The CTRL pins should not be left open. The CTRL pin
can also be used in conjunction with a PTC thermistor to
provide overtemperature protection for the LED load as
shown in Figure 2.
2V
VREF
45k
50k
CTRL1-3
470Ω
PTC
3492 F02
Figure 2
Thermal Considerations
The LT3492 is rated to a maximum input voltage of 30V
for continuous operation, and 40V for nonrepetitive one
second transients. Careful attention must be paid to the
internal power dissipation of the LT3492 at higher input
voltages and higher switching frequencies/output voltage
to ensure that a junction temperature of 125°C is not
exceeded. This is especially important when operating
at high ambient temperatures. Consider driving VIN from
5V or higher to ensure the fastest switching edges, and
minimize one source of switching loss. The exposed
pad on the bottom of the package must be soldered to
a ground plane. This ground should then be connected
to an internal copper ground plane with thermal vias
placed directly under the package to spread out the heat
dissipated by the LT3492.
Board Layout
The high speed operation of the LT3492 demands careful
attention to board layout and component placement. The
exposed pad of the package is the only GND terminal of
the IC and is important for thermal management of the
IC. Therefore, it is crucial to achieve a good electrical and
thermal contact between the exposed pad and the ground
plane of the board. Also, in boost configuration, the
Schottky rectifier and the capacitor between GND and the
cathode of the Schottky are in the high frequency switching
path where current flow is discontinuous. These elements
should be placed so as to minimize the path between SW
and the GND of the IC. To reduce electromagnetic interference (EMI), it is important to minimize the area of the SW
node. Use the GND plane under SW to minimize interplane
coupling to sensitive signals. To obtain good current
regulation accuracy and eliminate sources of channel to
channel coupling, the ISP and ISN inputs of each channel
of the LT3492 should be run as separate lines back to the
terminals of the sense resistor. Any resistance in series
with ISP and ISN inputs should be minimized. Avoid extensive routing of high impedance traces such as OVP and
VC. Make sure these sensitive signals are star coupled to
the GND under the IC rather than a GND where switching
currents are flowing. Finally, the bypass capacitor on the
VIN supply to the LT3492 should be placed as close as
possible to the VIN terminal of the device.
3492fa
12
LT3492
TYPICAL APPLICATIONS
Minimum BOM Buck Mode LED Driver
PVIN
58V
ISP1
ISP2
ISP3
330mΩ
330mΩ
330mΩ
ISN1
ISN2
ISN3
0.3A
0.3A
0.3A
10 LEDs
C6
0.22μF
C4
C5
0.22μF 0.22μF
L1
33μH
VIN
5V
C7
1μF
D1
D2
SW1
ISP1-3
ISN1-3
VIN
PWM1-3
SHDN
C1-C3
1μF
s3
L2
33μH
SW2
L3
33μH
D3
SW3
TG1-3
VC1-3
VREF
CTRL1-3
150k
LT3492
10k
FADJ
49.9k
470pF
1.3MHz
OVP1-3
GND
3492 TA07a
C1-C3, C7: MURATA GRM31CR72A105KA01L
C4-C6: MURATA GRM21BR71H224KA01
D1-D3: DIODES B1100
L1-L3: TDK VLF5014AT-330MR50
300:1 PWM Dimming at 100Hz
Efficiency
95
PWM
5V/DIV
90
85
EFFICIENCY (%)
ILED
0.5A/DIV
IL
0.5A/DIV
5μs/DIV
3492 TA07b
80
75
70
65
60
55
50
0
20
80
60
40
PWM DUTY CYCLE (%)
100
3492 TA07c
3492fa
13
LT3492
TYPICAL APPLICATIONS
Triple Boost 100mA × 12 LED Driver
PVIN
12V
C1
2.2μF
s3
L1
22μH
L2
22μH
D1
C2
1μF
L3
22μH
D2
ISP1
C3
1μF
1Ω
TG2
VIN
5V
C5
1μF
OVP1
20k
SW1
ISP1-3
ISN1-3
VIN
PWM1-3
SHDN
ISN3
TG3
M2
1M
100mA
1Ω
ISN2
M1
12 LEDs
ISP3
C4
1μF
1Ω
ISN1
TG1
D3
ISP2
M3
1M
12 LEDs
100mA
1M
OVP2
12 LEDs
20k
SW2
SW3
LT3492
TG1-3
OVP1-3
VC1-3
VREF
CTRL1-3
100mA
OVP3
20k
18.2k
2.2nF
150k
FADJ
GND
49.9k
C1: MURATA GRM31MR71C225KA35
C2-C4: MURATA GRM31CR72A105KA01L
C5: MURATA GRM31MR71H105KA88
D1-D3: DIODES B1100
L1-L3: TDK VLF5014AT-220MR62
M1-M3: ZETEX ZXMP6A13F
3492 TA03a
1.3MHz
Efficiency vs PWM Duty Cycle
1000:1 PWM Dimming at 100Hz
85
PWM
5V/DIV
80
EFFICIENCY (%)
75
ILED
0.1A/DIV
IL
0.5A/DIV
70
65
60
2μs/DIV
3492 TA03b
55
50
0
20
40
60
80
100
PWM DUTY CYCLE (%)
3492 TA03c
3492fa
14
LT3492
TYPICAL APPLICATIONS
Dual Boost LED Driver
PVIN
12V
C1
2.2μF
s3
L1
22μH
L2
22μH
L3
22μH
D1
C2
1μF
D2
ISP1
C3
1μF
1Ω
D3
ISP2
1Ω
ISN1
ISP3
C4
1μF
1Ω
ISN2
ISN3
M1
M2
1M
12 LEDs
100mA
SW1 TG1
VIN
3V TO 12V
C5
1μF
1M
OVP1
12 LEDs
20k
SW2
ISP1-3
ISN1-3
VIN
PWM1-3
SHDN
SW3 TG2
LT3492
200mA
OVP1-3
TG3
VC1-3
VREF
CTRL1-3
OVP2-3
20k
OPEN 18.2k
2.2nF
150k
FADJ
GND
49.9k
C1: MURATA GRM31MR71C225KA35
C2-C4: MURATA GRM31CR72A105KA01L
C5: MURATA GRM31MR71H105KA88
D1-D3: DIODES B1100
L1-L3: TDK VLF5014AT-220MR62
M1, M2: ZETEX ZXMP6A13F
1000:1 PWM Dimming at 100Hz for 200mA LEDs
3492 TA04
1.3MHz
Efficiency vs PWM Duty Cycle for 200mA LEDs
85
80
ILED
0.2A/DIV
75
EFFICIENCY (%)
PWM
5V/DIV
IL2
IL3
0.5A/DIV
2μs/DIV
3492 TA04b
70
65
60
55
50
0
20
40
60
80
100
PWM DUTY CYCLE (%)
3492 TA04c
3492fa
15
LT3492
TYPICAL APPLICATIONS
Triple Boost 100mA × 9 LED Driver with VIN Controlled Dimming
VIN
5V TO 16V
357k
C1
2.2μF
s3
L1
15μH
CTRL1-3
L2
15μH
L3
15μH
40.2k
D1
C2
1μF
D2
ISP1
C3
1μF
1Ω
ISP2
TG2
ISN3
TG3
M2
750k
C5
1μF
100mA
9 LEDs
20k
SW1
ISP1-3
ISN1-3
VIN
PWM1-3
SHDN
100mA
SW2
750k
OVP2
9 LEDs
20k
SW3
LT3492
TG1-3
OVP1-3
VC1-3
VREF
100
80
90
70
80
60
60
50
50
40
30
40
20
30
10
14
18
VIN (V)
1MHz
Efficiency vs VIN
90
70
100k
3492 TA08
EFFICIENCY (%)
ILED (mA)
2.2nF
FADJ
CTRL1-3
110
10
18.2k
430k
LED Current Decreasing with VIN
6
OVP3
100mA
20k
C1: MURATA GRM31MR71C225KA35
C2-C5: MURATA GRM31MR71H105KA88
D1-D3: ZETEX ZLLS400TA
L1-L3: TAIYO YUDEN NP04SZB 150M
M1-M3: ZETEX ZXMP6A13F
2
M3
750k
OVP1
GND
20
1Ω
ISN2
M1
9 LEDs
ISP3
C4
1μF
1Ω
ISN1
TG1
D3
0
4
8
12
16
VIN (V)
3492 TA08b
3492 TA08c
3492fa
16
LT3492
TYPICAL APPLICATIONS
Triple LED Driver Driving LED Strings in Buck, Boost and Buck-Boost Modes
VIN
10V TO 16V
C1
3.3μF
s3
ISP1
L2
22μH
330mΩ
L3
33μH
4 LEDs
0.1A
ISN1
D2
TG1
M1
ISP2
C3
1μF
TG3
1Ω
ISN3
ISN2
2 LEDs
1Ω
0.3A
TG2
M2
ISP3
C2
0.47μF
OVP3
100k
825k
0.1A
OVP2
C4
0.1μF
20k
C5
1μF
VIN
D1
SW1
3.9M
D3
10 LEDs
L1
6.8μH
M3
SW2
SW3
ISP1-3
ISN1-3
VIN
PWM1-3
SHDN
LT3492
TG1-3
OVP2-3
VC1-3
VREF
CTRL1-3
150k
18.2k
FADJ
49.9k
2.2nF
1.3MHz
OVP1
GND
3492 TA05
C1: MURATA GRM55DR71H335KA0193
C2: MURATA GRM21BR71H474KA88
C3, C5: MURATA GRM31MR71H105KA88
C4: MURATA GRM21BR71H104KA01B
D1: DIODES DFLS130
D2, D3: ROHM RB160M-60
3000:1 PWM Dimming at 100Hz for CH1 (Buck Mode)
L1: TDK VLF5014AT-6R8MR99
L2: TDK VLF5014AT-229MR62
L3: TDK VLF5014AT-330MR50
M1: ZETEX ZXMP3A13F
M2, M3 ZETEX ZXMP6A13F
3000:1 PWM Dimming at 100Hz for CH2 (Boost Mode)
PWM
5V/DIV
PWM
5V/DIV
ILED
0.5A/DIV
ILED
0.1A/DIV
IL
0.5A/DIV
IL
0.5A/DIV
1μs/DIV
3492 TA05b
1μs/DIV
3492 TA05c
3000:1 PWM Dimming at 100Hz for CH3 (Buck-Boost Mode)
PWM
5V/DIV
ILED
0.1A/DIV
IL
0.5A/DIV
1μs/DIV
3492 TA05d
3492fa
17
LT3492
TYPICAL APPLICATIONS
Triple Buck Mode LED Driver with Open LED Protection
PVIN
48V
TG1
ISP1
ISP2
ISP3
330mΩ
330mΩ
330mΩ
ISN1
ISN2
ISN3
TG2
M1
M2
C4
0.47μF
5.6k
0.3A
10 LEDs
5.6k
2k
L1
22μH
D1
D2
SW1
C7
1μF
5.6k
M5
OVP1
0.3A
10 LEDs
C6
0.47μF
C5
0.47μF
M4
VIN
5V
80.6k
80.6k
0.3A
10 LEDs
TG3
M3
80.6k
C1-C3
1μF
s3
L2
22μH
M6
OVP2 OVP1
2k
2k
L3
22μH
SW2
ISP1-3
ISN1-3
VIN
PWM1-3
SHDN
D3
SW3
LT3492
TG1-3
OVP1-3
VC1-3
VREF
CTRL1-3
10k
470pF
430k
FADJ
GND
100k
C1-C3, C7: MURATA GRM31CR72A105KA01L
C4-C6: MURATA GRM21BR72A474KA73
D1-D3: ROHM RB160M-60
L1-L3: TDK VLF5014AT-220MR62
M1-M3: ZETEX ZXMP6A13F
M4-M6: PHILIPS BC858B
2000:1 PWM Dimming at 100Hz
3492 TA02
1MHz
Efficiency vs PWM Duty Cycle for 200mA LEDs
95
PWM
5V/DIV
90
ILED
0.5A/DIV
IL
0.5A/DIV
1μs/DIV
3492 TA02b
EFFICIENCY (%)
85
80
75
70
65
60
55
50
0
20
80
60
40
PWM DUTY CYCLE (%)
100
3492 TA02c
3492fa
18
LT3492
PACKAGE DESCRIPTION
FE Package
28-Lead Plastic TSSOP (4.4mm)
(Reference LTC DWG # 05-08-1663)
Exposed Pad Variation EB
9.60 – 9.80*
(.378 – .386)
4.75
(.187)
4.75
(.187)
28 2726 25 24 23 22 21 20 19 18 1716 15
6.60 p0.10
2.74
(.108)
4.50 p0.10
SEE NOTE 4
0.45 p0.05
EXPOSED
PAD HEAT SINK
ON BOTTOM OF
PACKAGE
6.40
2.74
(.252
(.108)
BSC
1.05 p0.10
0.65 BSC
RECOMMENDED SOLDER PAD LAYOUT
4.30 – 4.50*
(.169 – .177)
0.09 – 0.20
(.0035 – .0079)
0.50 – 0.75
(.020 – .030)
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
2. DIMENSIONS ARE IN MILLIMETERS
(INCHES)
3. DRAWING NOT TO SCALE
1 2 3 4 5 6 7 8 9 10 11 12 13 14
0.25
REF
1.20
(.047)
MAX
0o – 8o
0.65
(.0256)
BSC
0.195 – 0.30
(.0077 – .0118)
TYP
0.05 – 0.15
(.002 – .006)
FE28 (EB) TSSOP 0204
4. RECOMMENDED MINIMUM PCB METAL SIZE
FOR EXPOSED PAD ATTACHMENT
*DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.150mm (.006") PER SIDE
3492fa
19
LT3492
PACKAGE DESCRIPTION
UFD Package
28-Lead Plastic QFN (4mm × 5mm)
(Reference LTC DWG # 05-08-1712 Rev B)
0.70 p0.05
4.50 p 0.05
3.10 p 0.05
2.50 REF
2.65 p 0.05
3.65 p 0.05
PACKAGE OUTLINE
0.25 p0.05
0.50 BSC
3.50 REF
4.10 p 0.05
5.50 p 0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
4.00 p 0.10
(2 SIDES)
0.75 p 0.05
R = 0.05
TYP
PIN 1 NOTCH
R = 0.20 OR 0.35
s 45o CHAMFER
2.50 REF
R = 0.115
TYP
27
28
0.40 p 0.10
PIN 1
TOP MARK
(NOTE 6)
1
2
5.00 p 0.10
(2 SIDES)
3.50 REF
3.65 p 0.10
2.65 p 0.10
(UFD28) QFN 0506 REV B
0.200 REF
0.00 – 0.05
0.25 p 0.05
0.50 BSC
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220 VARIATION (WXXX-X).
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON THE TOP AND BOTTOM OF PACKAGE
3492fa
20
LT3492
REVISION HISTORY
REV
DATE
DESCRIPTION
PAGE NUMBER
A
04/10
Corrected Pin Names for FE Package in Pin Configuration Section
2
3492fa
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.
21
LT3492
TYPICAL APPLICATION
Triple Buck-Boost Mode 100mA × 4 LED Driver
PVIN
10V TO 16V
C1
2.2μF
4 LEDs
100mA
L1
22μH
ISN1
1Ω
ISP1
D1
M2
TG2
3.9M
C4
0.1μF
PVIN
C8
1μF
1Ω
100k
ISP3
D3
C5
1μF
3.9M
IL
0.5A/DIV
C7
1μF
1μs/DIV
3492 TA06b
PVIN
SW3
LT3492
TG1-3
OVP1-3
VC1-3
VREF
CTRL1-3
18.2k
150k
D1-D3: ROHM RB160M-60
L1-L3: TDK VLF5014AT-220MR62
M1-M3: ZETEX ZXMP6A13F
2.2nF
3492 TA06
FADJ
GND
C1: MURATA GRM31MR71E225KA93
C2, C4, C6: MURATA GRM21BR71H104KA01B
C3, C5, C7: MURATA GRM31MR71H105KA88
C8: MURATA GRM31MR71E105KA93
ILED
0.1A/DIV
OVP3
100k
C6
0.1μF
PVIN
SW2
PWM
5V/DIV
M3
ISN3
OVP2
ISP2
D2
C3
1μF
SW1
ISP1-3
ISN1-3
VIN
PWM1-3
SHDN
3.9M
1Ω
100k
3000:1 PWM Dimming at 100Hz
TG3
ISN2
OVP1
C2
0.1μF
4 LEDs
100mA
L3
22μH
M1
TG1
VIN
5V TO 16V
4 LEDs
100mA
L2
22μH
49.9k
1.3MHz
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT3496
Triple 0.75A, 2.1MHz, 45V LED Driver
VIN: 3V to 30V, VOUT(MAX) = 45V, Dimming = 3000:1, ISD < 1μA,
4mm × 5mm QFN and TSSOP16E Packages
LT3474
36V, 1A (ILED), 2MHz, Step-Down LED Driver
VIN: 4V to 36V, VOUT(MAX) = 13.5V, True Color PWM Dimming = 400:1,
ISD < 1μA, TSSOP16E Package
LT3475
Dual 1.5A (ILED), 36V, 2MHz Step-Down LED Driver
VIN: 4V to 36V, VOUT(MAX) = 13.5V, True Color PWM Dimming = 3000:1,
ISD < 1μA, TSSOP20E Package
LT3476
Quad Output 1.5A, 36V, 2MHz High Current LED Driver VIN: 2.8V to 16V, VOUT(MAX) = 36V, True Color PWM Dimming = 1000:1,
ISD < 10μA, 5mm × 7mm QFN Package
with 1000:1 Dimming
LT3477
3A, 42V, 3MHz Boost, Buck-Boost, Buck LED Driver
VIN: 2.5V to 25V, VOUT(MAX) = 40V, Dimming = Analog/PWM, ISD < 1μA,
QFN and TSSOP20E Packages
LT3478/LT3478-1
4.5A, 42V, 2.5MHz High Current LED Driver with
3000:1 Dimming
VIN: 2.8V to 36V, VOUT(MAX) = 42V, True Color PWM Dimming = 3000:1,
ISD < 3μA, TSSOP16E Package
LT3486
Dual 1.3A, 2MHz High Current LED Driver
VIN: 2.5V to 24V, VOUT(MAX) = 36V, True Color PWM Dimming = 1000:1,
ISD < 1μA, 5mm × 3mm DFN and TSSOP16E Packages
LT3517
1.5A, 2.5MHz, 45V LED Driver
VIN: 3V to 30V, VOUT(MAX) = 45V, Dimming = 3000:1, ISD < 1μA,
4mm × 4mm QFN and TSSOP16E Packages
LT3518
2.3A, 2.5MHz, 45V LED Driver
VIN: 3V to 30V, VOUT(MAX) = 45V, Dimming = 3000:1, ISD < 1μA,
4mm × 4mm QFN and TSSOP16E Packages
LT3755/LT3755-1
40VIN , 75VOUT, Full Featured LED Controller
VIN: 4.5V to 40V, VOUT(MAX) = 75V, True Color PWM Dimming = 3000:1,
ISD < 1μA, 3mm × 3mm QFN-16 and MS16E Packages
LT3756-1
100V High Current LED Controller
VIN: 6V to 100V, VOUT(MAX) = 100V, True Color PWM Dimming = 3000:1,
ISD < 1μA, 3mm × 3mm QFN-16 and MS16E Packages
LTC®3783
High Current LED Controller
VIN: 3V to 36V, VOUT(MAX) = Ext FET, True Color PWM Dimming = 3000:1,
ISD < 20μA, 5mm × 4mm QFN10 and TSSOP16E Packages
3492fa
22 Linear Technology Corporation
LT 0410 REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
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www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2009