LT3465/LT3465A
1.2MHz/2.4MHz White
LED Drivers with Built-in
Schottky in ThinSOT
FEATURES
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DESCRIPTIO
Inherently Matched LED Current
Drives Up to Six LEDs from a 3.6V Supply
No External Schottky Diode Required
1.2MHz Switching Frequency (LT3465)
2.4MHz Switching Frequency Above AM Broadcast
Band (LT3465A)
V
IN
Range: 2.7V to 16V
V
OUT(MAX)
= 30V
Automatic Soft-Start (LT3465)
Open LED Protection
High Efficiency: 81% (LT3465) 79% (LT3465A)
Typical
Requires Only 0.22µF Output Capacitor
Low Profile (1mm) SOT-23
The LT
®
3465/LT3465A are step-up DC/DC converters
designed to drive up to six LEDs in series from a Li-Ion cell.
Series connection of the LEDs provides identical LED
currents and eliminates the need for ballast resistors.
These devices integrate the Schottky diode required exter-
nally on competing devices. Additional features include
output voltage limiting when LEDs are disconnected, one-
pin shutdown and dimming control. The LT3465 has
internal soft-start.
The LT3465 switches at 1.2MHz, allowing the use of tiny
external components. The faster LT3465A switches at
2.4MHz. Constant frequency switching results in low input
noise and a small output capacitor. Just 0.22µF is required
for 3-, 4- or 5-LED applications.
The LT3465 and LT3465A are available in the low profile
(1mm) 6-lead SOT-23 (ThinSOT
TM
) package.
, LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a
trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
APPLICATIO S
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Cellular Phones
PDAs, Handheld Computers
Digital Cameras
MP3 Players
GPS Receivers
TYPICAL APPLICATIO
L1
22µH
3V TO 5V
Conversion Efficiency
V
IN
= 3.6V
80 4 LEDs
78
EFFICIENCY (%)
SW
V
IN
SHUTDOWN
AND DIMMING
CONTROL
C1
1µF
LT3465/
LT3465A
FB
CTRL
GND
C2
0.22µF
10Ω
3465A F01a
82
V
OUT
76
74
72
70
68
66
64
62
60
0
5
10
LED CURRENT (mA)
3465A F01b
C1, C2: X5R OR X7R DIELECTRIC
L1: MURATA LQH32CN220
Figure 1. Li-Ion Powered Driver for Four White LEDs
U
LT3465
LT3465A
15
20
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U
1
LT3465/LT3465A
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
OUT
1
GND 2
FB 3
6 SW
5 V
IN
4 CTRL
Input Voltage (V
IN
) ................................................. 16V
SW Voltage ............................................................. 36V
FB Voltage ................................................................ 2V
CTRL Voltage .......................................................... 10V
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Maximum Junction Temperature ......................... 125°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
JMAX
= 125°C,
θ
JA
= 256°C/W IN FREE AIR
θ
JA
= 120°C ON BOARD OVER GROUND PLANE
ORDER PART NUMBER
LT3465ES6
LT3465AES6
S6 PART MARKING
LTH2
LTAFT
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
Feedback Voltage
FB Pin Bias Current
Supply Current
Switching Frequency
Maximum Duty Cycle
Switch Current Limit
Switch V
CESAT
Switch Leakage Current
V
CTRL
for Full LED Current
V
CTRL
to Enable Chip
V
CTRL
to Shut Down Chip
CTRL Pin Bias Current
T
A
= 85°C
T
A
= –40°C
Soft-Start Time
Schottky Forward Drop
Schottky Leakage Current
I
D
= 150mA
V
R
= 30V
I
SW
= 250mA
V
SW
= 5V
Not Switching
CTRL = 0V
0°C
≤
T
A
≤
85°C
CONDITIONS
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 3V, V
CTRL
= 3V, unless otherwise noted.
MIN
2.7
16
188
10
1.9
2.0
0.8
●
●
LT3465
TYP
MAX
MIN
2.7
LT3465A
TYP
MAX
16
UNITS
V
V
mV
nA
mA
µA
MHz
%
mA
mV
200
35
2.6
3.2
1.2
93
340
300
0.01
212
100
3.3
5.0
1.6
188
10
1.9
2.0
1.8
90
225
200
35
2.6
3.2
2.4
93
340
300
0.01
212
100
3.3
5.0
2.8
90
225
5
1.8
150
50
5
1.8
●
●
150
48
40
60
60
50
75
600
0.7
4
72
60
90
50
48
40
60
60
50
75
0.7
4
72
60
90
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
The LT3465E/LT3465AE are guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
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µA
V
mV
mV
µA
µA
µA
µs
V
µA
W
U
U
W W
W
LT3465/LT3465A
TYPICAL PERFOR A CE CHARACTERISTICS
Switch Saturation Voltage (V
CESAT
)
450
SWITCH SATURATION VOLTAGE (mV)
T
A
= 25°C
SCHOTTKY FORWARD CURRENT (mA)
400
350
300
250
200
150
100
50
0
0
50
100 150 200 250
SWITCH CURRENT (mA)
300
350
150
100
50
0
I
Q
(µA)
V
FB
vs V
CTRL
250
T
A
= 25°C
OUTPUT CLAMP VOLTAGE (V)
FEEDBACK VOLTAGE (mV)
200
25
20
15
10
5
INPUT CURRENT (mA)
150
100
50
0
0
1
0.5
1.5
CONTROL VOLTAGE (V)
Switching Waveforms (LT3465)
V
SW
10V/DIV
I
L
100mA/DIV
V
OUT
100mV/DIV
V
SW
10V/DIV
I
L
50mA/DIV
V
OUT
50mV/DIV
V
IN
= 3.6V
4 LEDs
20mA, 22µH
200ns/DIV
SWITCHING FREQUENCY (MHz)
U W
3465A G01
Schottky Forward Voltage Drop
300
250
200
T
A
= 25°C
Shutdown Quiescent Current
(CTRL = 0V)
30
27
24
21
18
15
12
9
6
3
T
A
= 25°C
0
1000
400
600
800
200
SCHOTTKY FORWARD DROP (mV)
1200
0
2
4
6
10
8
V
IN
(V)
12
14
16
3465A G02
3465A G03
Open-Circuit Output Clamp Voltage
35
30
4
5
Input Current in Output Open Circuit
T
A
= 25°C
T
A
= 25°C
3
2
1
0
2
3465A G04
0
2
4
10
8
12
6
INPUT VOLTAGE (V)
14
16
2
2.5
4
3.5
3
INPUT VOLTAGE (V)
4.5
5
3465A G05
3465A G06
Switching Waveforms (LT3465A)
3.0
2.5
2.0
1.5
Switching Frequency
LT3465A
LT3465
1.0
0.5
0
–50
3465A G07a
V
IN
= 3.6V
4 LEDs
20mA, 22µH
100ns/DIV
3465A G07b
50
0
TEMPERATURE (°C)
100
4365A G08
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LT3465/LT3465A
TYPICAL PERFOR A CE CHARACTERISTICS
Feedback Voltage
210
208
FEEDBACK VOLTAGE (mV)
206
204
I
Q
(mA)
2.0
1.5
1.0
0.5
0
70
90
3465A G09
CURRENT LIMIT (mA)
–50°C
25°C
100°C
0
5
10
V
IN
(V)
15
20
3465A G10
202
200
198
196
194
192
190
–50 –30 –10 10 30 50
TEMPERATURE (°C)
V
IN
= 3.6V, 4 LEDs
85
SCHOTTKY LEAKAGE CURRENT (µA)
LT3465
LT3465A
80
EFFICIENCY (%)
75
15mA
10mA
70
65
60
–50
50
0
TEMPERATURE (°C)
4
U W
Quiescent Current (CTRL = 3V)
3.0
2.5
Switching Current Limit
400
350
300
250
200
150
100
50
0
0
20
60
DUTY CYCLE (%)
40
80
–50°C
25°C
100°C
100
3465A G11
Schottky Leakage Current
8
20mA
7
V
R
= 25
6
5
4
3
2
1
0
–50
0
50
100
3465A G13
V
R
= 16
V
R
= 10
100
3465A G12
TEMPERATURE (°C)
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LT3465/LT3465A
PI FU CTIO S
V
OUT
(Pin 1):
Output Pin. Connect to output capacitor and
LEDs. Minimize trace between this pin and output capaci-
tor to reduce EMI.
GND (Pin 2):
Ground Pin. Connect directly to local ground
plane.
FB (Pin 3):
Feedback Pin. Reference voltage is 200mV.
Connect LEDs and a resistor at this pin. LED current is
determined by the resistance and CTRL pin voltage:
CTRL (Pin 4):
Dimming Control and Shutdown Pin. Ground
this pin to shut down the device. When V
CTRL
is greater
than about 1.8V, full-scale LED current is generated.
When V
CTRL
is less than 1V, LED current is reduced.
Floating this pin places the device in shutdown mode.
V
IN
(Pin 5):
Input Supply Pin. Must be locally bypassed
with a 1µF X5R or X7R type ceramic capacitor.
SW (Pin 6):
Switch Pin. Connect inductor here.
⎛
⎞⎞
⎛
⎛
200mV
⎞
⎜
⎟⎟
⎜
exp
⎜
⎠
⎝
26mV
⎟
1
⎜
• 200mV – 26mV • 1n
⎜
I
LED
=
+
1
⎟ ⎟
for V
CTRL
>
150mV
⎜
R
FB
⎜
⎛
V
CTRL
(
mV
)
⎞ ⎟ ⎟
p
⎜
⎟⎟
⎜
exp
⎜
⎝
5mV • 26mV
⎟ ⎠ ⎠
⎠
⎝
⎝
U
U
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