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LT3466EDD#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
1
LT3466
3466fa
Dual Full Function White LED
Step-Up Converter with
Built-In Schottky Diodes
Figure 1. Li-Ion Powered Driver for 8/8 White LEDs
■
Drives Up to 20 White LEDs (10 in Series
per Converter) from a 3.6V Supply
■
Two Independent Step-Up Converters Capable of
Driving Asymmetric LED Strings
■
Independent Dimming and Shutdown Control
of the Two LED Strings
■
Internal Schottky Diodes
■
Internal Soft-Start Eliminates Inrush Current
■
Open LED Protection (39.5V Max V
OUT
)
■
Fixed Frequency Operation Up to 2MHz
■
81% Efficiency Driving 16 White LEDs at 15mA
(Eight per Driver) from a 3.6V Supply
■
Wide Input Voltage Range: 2.7V to 24V
■
Available in 10-Pin DFN and 16-Pin Thermally
Enhanced TSSOP Packages
, LTC and LT are registered trademarks of Linear Technology Corporation.
■
Main/Sub Displays
■
Digital Cameras, Sub-Notebook PCs
■
PDAs, Handheld Computers
■
Automotive
LT
®
3466 is a dual full function step-up DC/DC converter
specifically designed to drive up to 20 White LEDs (10 in
series per converter) with a constant current. 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 two independent converters are capable of driving
asymmetric LED strings. The dimming of the two LED
strings can also be controlled independently. The LT3466
is ideal for providing backlight for main and sub-displays
in cell phones and other handheld devices.
The LT3466 operating frequency can be set with an
external resistor over a 200kHz to 2MHz range. A low
200mV feedback voltage minimizes power loss in the
current setting resistor for better efficiency. Additional
features include output voltage limiting when LEDs are
disconnected and internal soft-start.
The LT3466 is available in the 10-pin (3mm × 3mm ×
0.75mm) DFN and 16-pin thermally enhanced TSSOP
packages.
CTRL1 GND CTRL2
R
T
SW1 SW2V
IN
3V TO 5V
L2
47µH
1µF
2.2µF 2.2µF
LED1 LED2
L1
47µH
LT3466
SHUTDOWN
AND DIMMING
CONTROL 2
SHUTDOWN
AND DIMMING
CONTROL 1
V
OUT1
FB1
10Ω 10Ω
3466 F01a
V
OUT2
FB2
63.4k
OFF ON OFF ON
Conversion Efficiency
LED CURRENT (mA)
0
EFFICIENCY (%)
70
75
20
3466 F01b
60
50
65
55
5
10
15
85
V
IN
= 3.6V
8/8 LEDs
80
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
2
LT3466
3466fa
Input Voltage (V
IN
) ................................................... 24V
SW1, SW2 Voltages ................................................ 44V
V
OUT1
, V
OUT2
Voltages ............................................. 44V
CTRL1, CTRL2 Voltages ........................................... 24V
FB1, FB2, R
T
Voltages ................................................ 2V
Operating Temperature Range (Note 2) ... –40°C to 85°C
ABSOLUTE AXI U RATI GS
WWWU
PACKAGE/ORDER I FOR ATIO
UU
W
T
JMAX
= 125°C, θ
JA
= 43°C/W, θ
JC
= 2.96°C/W
EXPOSED PAD (PIN 11) IS GND
MUST BE SOLDERED TO PCB
ORDER PART
NUMBER
DD PART MARKING
LBBH
LT3466EDD
Consult LTC Marketing for parts specified with wider operating temperature ranges.
TOP VIEW
11
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
10
9
6
7
8
4
5
3
2
1
FB1
CTRL1
R
T
CTRL2
FB2
V
OUT1
SW1
V
IN
SW2
V
OUT2
(Note 1)
Maximum Junction Temperature ......................... 125°C
Storage Temperature Range
DFN .................................................. –65°C to 125°C
TSSOP .............................................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec, TSSOP)..... 300°C
ORDER PART
NUMBER
FE PART MARKING
3466EFE
LT3466EFE
FE PACKAGE
16-LEAD PLASTIC TSSOP
1
2
3
4
5
6
7
8
TOP VIEW
16
15
14
13
12
11
10
9
GND
NC
V
OUT1
SW1
V
IN
SW2
V
OUT2
GND
GND
FB1
CTRL1
NC
R
T
CTRL2
FB2
GND
17
T
JMAX
= 125°C, θ
JA
= 38°C/W, θ
JC(PAD)
= 10°C/W
EXPOSED PAD (PIN 17) IS GND
MUST BE SOLDERED TO PCB
ELECTRICAL CHARACTERISTICS
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.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Operating Voltage 2.7 V
Maximum Operating Voltage 24 V
FB1 Voltage ● 192 200 208 mV
FB2 Voltage ● 192 200 208 mV
Offset Voltage (V
OS
) Between FB1 and FB2 Voltages V
OS
= |FB1 – FB2| 0 1.5 7.5 mV
FB1 Pin Bias Current V
FB1
= 0.2V (Note 3) 10 50 nA
FB2 Pin Bias Current V
FB2
= 0.2V (Note 3) 10 50 nA
Quiescent Current V
FB1
= V
FB2
= 0.3V 5 7.5 mA
CTRL1 = CTRL2 = 0V 16 25 µA
Switching Frequency R
T
= 48.7k 0.8 1 1.2 MHz
Oscillator Frequency Range (Note 4) 200 2000 kHz
Nominal R
T
Pin Voltage R
T
= 48.7k 0.54 V
Maximum Duty Cycle R
T
= 48.7k ● 90 96 %
R
T
= 20.5k 92 %
R
T
= 267k 99 %
3
LT3466
3466fa
ELECTRICAL CHARACTERISTICS
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.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Converter 1 Current Limit (Note 5) ● 320 400 mA
Converter 2 Current Limit (Note 5) ● 320 400 mA
Converter 1 V
CESAT
I
SW1
= 300mA 360 mV
Converter 2 V
CESAT
I
SW2
= 300mA 360 mV
Switch 1 Leakage Current V
SW1
= 10V 0.01 5 µA
Switch 2 Leakage Current V
SW2
= 10V 0.01 5 µA
CTRL1 Voltage for Full LED Current ● 1.8 V
CTRL2 Voltage for Full LED Current ● 1.8 V
CTRL1 or CTRL2 Voltage to Turn-On the IC 150 mV
CTRL1 and CTRL2 Voltages to Shut Down the IC 50 mV
CTRL1, CTRL2 Pin Bias Current V
CTRL1
= V
CTRL2
= 1V ● 81012 µA
V
OUT1
Overvoltage-Lockout Threshold V
OUT1
Rising 39.5 V
V
OUT2
Overvoltage-Lockout Threshold V
OUT2
Rising 39.5 V
Schottky 1 Forward Drop I
SCHOTTKY1
= 300mA 0.85 V
Schottky 2 Forward Drop I
SCHOTTKY2
= 300mA 0.85 V
Schottky 1 Reverse Leakage V
OUT1
= 20V 5 µA
Schottky 2 Reverse Leakage V
OUT2
= 20V 5 µA
Soft-Start Time (Switcher 1) 600 µs
Soft-Start Time (Switcher 2) 600 µs
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LT3466E 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.
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Switching Waveforms Transient Response
V
OUT1
50mV/DIV
V
SW1
20V/DIV
I
L1
100mA/DIV
V
IN
= 3.6V 0.5µs/DIV 3466 G01
CIRCUIT OF FIGURE 1
V
OUT1
0.5V/DIV
V
CTRL1
2V/DIV
I
L1
200mA/DIV
V
IN
= 3.6V 50µs/DIV 3466 G02
I
LED1
= 20mA TO 10mA
CIRCUIT OF FIGURE 1
Note 3: Current flows out of the pin.
Note 4: Guaranteed by design and test correlation, not production tested.
Note 5: Current limit is guaranteed by design and/or correlation to static
test. Slope compensation reduces current limit at high duty cycle.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

LT3466EDD#PBF

Mfr. #:
Buy LT3466EDD#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
LED Lighting Drivers Dual White LED Step-up Converter w/ Schottky
Lifecycle:
New from this manufacturer.
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