LT3466-1
White LED Driver and Boost
Converter in 3mm
×
3mm
DFN Package
FEATURES
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DESCRIPTIO
Drives Up to 10 White LEDs from a 3.6V Supply
Two Independent Step-Up DC/DC Converters
Independent Dimming and Shutdown Control
of the Outputs
±1.5%
Output Voltage Accuracy (Boost Converter)
±4%
LED Current Programming Accuracy
Internal Schottky Diodes
Internal Soft-Start Eliminates Inrush Current
Output Overvoltage Protection (39.5V Max V
OUT
)
Fixed Frequency Operation Up to 2MHz
83% Efficiency Driving 8 White LEDs at 15mA
from a 3.6V Supply
Wide Input Voltage Range: 2.7V to 24V
Tiny (3mm
×
3mm) 10-Lead DFN Package
LT
®
3466-1 is a dual switching regulator that combines a
white LED driver and a boost converter in a low profile,
small footprint (3mm
×
3mm
×
0.75mm) DFN package.
The LED driver can be configured to drive up to 10 White
LEDs in series and the boost converter can be used for
generating the LCD bias voltages or driving a secondary
OLED display. Series connection of the LEDs provides
identical LED currents resulting in uniform brightness and
eliminating the need for ballast resistors and expensive
factory calibration.
The LT3466-1 provides independent dimming and shut-
down control of the two converters. The operating fre-
quency can be set with an external resistor over a 200kHz
to 2MHz range. The white LED driver features a low 200mV
reference, thereby minimizing power loss in the current
setting resistor for better efficiency. The boost converter
achieves
±1.5%
output voltage accuracy by the use of a
precision 0.8V reference. Protection features include out-
put overvoltage protection and internal soft-start. Wide
input supply range allows operation from 2.7V to 24V.
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
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White LED and OLED Displays
Digital Cameras, Sub-Notebook PCs
PDAs, Handheld Computers
TFT - LCD Bias Supply
Automotive
TYPICAL APPLICATIO
33µH
3V TO 5V
33µH
1µF
90
85
SW1
V
IN
SW2
80
EFFICIENCY (%)
75
70
65
60
55
6 LEDs
1µF
V
OUT1
LT3466-1
V
OUT2
1µF
16V
30mA
475k
FB1
CTRL1
10Ω
SHUTDOWN
AND DIMMING
CONTROL 1
63.4k
R
T
GND
FB2
CTRL2
SHUTDOWN
AND DIMMING
CONTROL 2
24.9k
34661 F01a
50
Figure 1. Li-Ion Powered Driver for 6 White LEDs and OLED Display
34661f
U
Conversion Efficiency
V
IN
= 3.6V
LED DRIVER
BOOST CONVERTER
0
5
10
15
20
25
30
OUTPUT CURRENT (mA)
34661 F01b
U
U
1
LT3466-1
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
OUT1
SW1
V
IN
SW2
V
OUT2
1
2
3
4
5
11
10 FB1
9 CTRL1
8 R
T
7 CTRL2
6 FB2
Input Voltage (V
IN
) ................................................... 24V
SW1, SW2 Voltages ................................................ 44V
V
OUT1
, V
OUT2
Voltages ............................................. 44V
CTRL1, CTRL2 Voltages ........................................... 24V
FB1, FB2 Voltages ...................................................... 2V
Operating Temperature Range (Note 2) ... –40°C to 85°C
Storage Temperature Range .................. –65°C to 125°C
Junction Temperature .......................................... 125°C
ORDER PART
NUMBER
LT3466EDD-1
DD PACKAGE
10-LEAD (3mm
×
3mm) PLASTIC DFN
DD PART MARKING
LBRX
T
JMAX
= 125°C,
θ
JA
= 43°C/W,
θ
JC
= 3°C/W
EXPOSED PAD (PIN 11) IS GND
MUST BE SOLDERED TO PCB
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
Minimum Operating Voltage
Maximum Operating Voltage
FB1 Voltage
FB2 Voltage
FB1 Pin Bias Current
FB2 Pin Bias Current
Quiescent Current
Switching Frequency
Oscillator Frequency Range
Nominal R
T
Pin Voltage
Maximum Duty Cycle
The
●
denotes specifications that apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= 3V, V
CTRL1
= 3V, V
CTRL2
= 3V, unless otherwise specified.
CONDITIONS
MIN
2.7
22
●
●
TYP
MAX
UNITS
V
V
mV
mV
nA
nA
mA
µA
MHz
kHz
V
%
%
%
mA
mA
mV
mV
192
788
200
800
10
10
5
16
208
812
50
50
7.5
25
1.25
2000
V
FB1
= 0.2V (Note 3)
V
FB2
= 0.8V (Note 3)
V
FB1
= V
FB2
= 1V
CTRL1 = CTRL2 = 0V
R
T
= 48.7k
(Note 4)
R
T
= 48.7k
R
T
= 48.7k
R
T
= 20.5k
R
T
= 267k
●
0.75
200
1
0.54
90
96
92
99
400
400
320
320
0.01
0.01
5
5
Converter 1 Current Limit
Converter 2 Current Limit
Converter 1 V
CESAT
Converter 2 V
CESAT
Switch 1 Leakage Current
Switch 2 Leakage Current
CTRL1 Voltage for Full LED Current
CTRL2 Voltage for Full Feedback Voltage
CTRL1 or CTRL2 Voltage to Turn On the IC
CTRL1 and CTRL2 Voltages to Shut Down Chip
CTRL1 Pin Bias Current
CTRL2 Pin Bias Current
V
CTRL1
= 1V
V
CTRL2
= 1V (Note 3)
I
SW1
= 300mA
I
SW2
= 300mA
V
SW1
= 10V
V
SW2
= 10V
●
●
310
310
●
●
1.8
1
150
70
●
●
6
9
10
12.5
120
2
U
µA
µA
V
V
mV
mV
µA
nA
34661f
W
U
U
W W
W
LT3466-1
ELECTRICAL CHARACTERISTICS
PARAMETER
V
OUT1
Overvoltage Threshold
V
OUT2
Overvoltage Threshold
Schottky 1 Forward Drop
Schottky 2 Forward Drop
Schottky 1 Reverse Leakage
Schottky 2 Reverse Leakage
Soft-Start Time (Switcher 1)
Soft-Start Time (Switcher 2)
The
●
denotes specifications that apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. V
IN
= 3V, V
CTRL1
= 3V, V
CTRL2
= 3V, unless otherwise specified.
CONDITIONS
MIN
TYP
39.5
39.5
I
SCHOTTKY1
= 300mA
I
SCHOTTKY2
= 300mA
V
OUT1
= 20V
V
OUT2
= 20V
600
600
0.85
0.85
5
5
MAX
UNITS
V
V
V
V
µA
µA
µs
µs
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The LTC3466-1E is guaranteed to meet specified performance
from 0°C to 70°C. Specifications over the –40°C to 85°C operating range
are assured by design, characterization and correlation with statistical
process controls.
Note 3:
Current flows out of the pin.
Note 4:
Guaranteed by design and test correlation, not production tested.
TYPICAL PERFOR A CE CHARACTERISTICS
Switching Waveforms
(LED Driver)
V
OUT1
100mV/DIV
(AC-COUPLED)
V
SW1
20V/DIV
I
L1
100mA/DIV
V
IN
= 3.6V
0.5µs/DIV
6 LEDs AT 20mA
CIRCUIT OF FIGURE 1
34661 G01
V
FB1
vs V
CTRL1
250
V
IN
= 3.6V
6 LEDs
900
200
V
FB1
(mV)
V
FB2
(mV)
150
100
50
0
0
0.5
U W
1
T
A
= 25°C unless otherwise specified
Switching Waveforms
(Boost Converter)
V
OUT2
100mV/DIV
(AC-COUPLED)
V
SW2
20V/DIV
I
L2
100mA/DIV
V
IN
= 3.6V
0.5µs/DIV
V
OUT2
= 16V/30mA
CIRCUIT OF FIGURE 1
34661 G02
V
FB2
vs V
CTRL2
V
IN
= 3.6V
V
OUT2
= 16V
800
700
600
500
400
300
200
100
1.5
2
34661 G03
0
0
0.5
1
V
CTRL2
(V)
1.5
2
34661 G16
V
CTRL1
(V)
34661f
3
LT3466-1
TYPICAL PERFOR A CE CHARACTERISTICS
T
A
= 25°C unless otherwise specified
Switch Current Limit vs Duty Cycle
500
450
400
CURRENT LIMIT (mA)
T
A
= –50°C
QUIESCENT CURRENT (mA)
350
300
250
200
150
100
50
0
0
20
T
A
= 85°C
5
4
3
2
1
0
SHUTDOWN CURRENT (µA)
60
40
DUTY CYCLE (%)
Open-Circuit Output Clamp
Voltage
41.00
40.50
40.00
V
OUT2
39.50
V
OUT1
39.00
38.50
38.00
2
4
6
8 10 12 14 16 18 20 22 24
V
IN
(V)
34661 G07
R
T
= 63.4k
OUTPUT CLAMP VOLTAGE (V)
OUTPUT CLAMP VOLTAGE (V)
40
V
OUT1
39
INPUT CURRENT (mA)
R
T
vs Oscillator Frequency
1000
OSCILLATOR FREQUENCY (kHz)
R
T
(kΩ)
100
10
200
600
1000
1400
1800
OSCILLATOR FREQUENCY (kHz)
34661 G10
4
U W
T
A
= 25°C
80
Quiescent Current
(CTRL1 = CTRL2 = 3V)
7
6
UVLO
70
60
50
40
Shutdown Current
(CTRL1 = CTRL2 = 0V)
T
A
= –50°C
T
A
= 25°C
T
A
= 100°C
30
20
10
0
2
4
6
8 10 12 14 16 18 20 22 24
V
IN
(V)
34661 G06
100
34661 G05
0
4
8
12
V
IN
(V)
16
20
24
34661 G04
Open-Circuit Output Clamp
Voltage
42
R
T
= 63.4k
Input Current with Output 1 and
Output 2 Open Circuit
20
R
T
= 63.4k
41
V
OUT2
16
12
8
38
4
37
–50
–25
50
25
0
75
TEMPERATURE (°C)
100
125
0
2
4
6
8 10 12 14 16 18 20 22 24
V
IN
(V)
34661 G09
34661 G08
Oscillator Frequency vs V
IN
1100
R
T
= 48.7k
1000
900
800
2
4
6
8 10 12 14 16 18 20 22 24
V
IN
(V)
34661 G11
34661f
LT3466-1
TYPICAL PERFOR A CE CHARACTERISTICS
T
A
= 25°C unless otherwise specified
Oscillator Frequency
vs Temperature
1100
V
IN
= 3.6V
R
T
= 48.7k
OSCILLATOR FREQUENCY (kHz)
1000
CTRL VOLTAGE (mV)
900
800
–50
–25
Schottky Forward Voltage Drop
400
SCHOTTKY FORWARD CURRENT (mA)
350
300
250
200
150
100
50
0
0
800
600
SCHOTTKY FORWARD DROP (mV)
200
400
1000
SCHOTTKY LEAKAGE CURRENT (µA)
FB2 Pin Voltage vs Temperature
0.810
0.805
0.800
0.795
0.790
0.785
0.780
–50
V
IN
= 3V
V
OUT2
= 16V/30mA
0
∆V
OUT2
/V
OUT2
(%)
FB2 VOLTAGE (V)
–25
U W
CTRL Voltages to Shut Down
the IC
150
125
CTRL1
100
CTRL2
75
50
25
0
–50
V
IN
= 3.6V
0
25
50
TEMPERATURE (°C)
75
100
34661 G12
–25
0
25
50
TEMPERATURE (°C)
75
100
34661 G13
Schottky Leakage Current
8
6
4
V
R
= 36V
V
R
= 20V
2
0
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
34661 G14
34661 G015
FB2 Pin Load Regulation
V
IN
= 3V
V
OUT2
= 16V
–0.20
–0.40
–0.60
–0.80
–1.00
75
0
25
50
TEMPERATURE (°C)
100
125
0
10
20
LOAD CURRENT (mA)
30
34661 G18
34661 G17
34661f
5
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