FEATURES
LT3465/LT3465A
1.2MHz/2.4MHz White
LED Drivers with Built-in
Schottky in ThinSOT
U
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)
■
VIN Range: 2.7V to 16V
■
V
OUT(MAX)
■
Automatic Soft-Start (LT3465)
■
Open LED Protection
■
High Efficiency: 81% (LT3465) 79% (LT3465A)
= 30V
Typical
■
Requires Only 0.22µF Output Capacitor
■
Low Profile (1mm) SOT-23
U
APPLICATIO S
■
Cellular Phones
■
PDAs, Handheld Computers
■
Digital Cameras
■
MP3 Players
■
GPS Receivers
®
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 externally on competing devices. Additional features include
output voltage limiting when LEDs are disconnected, onepin 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
, 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.
TM
) package.
U
TYPICAL APPLICATIO
L1
22µH
3V TO 5V
SW V
IN
LT3465/
LT3465A
GND
OUT
FB
V
CTRL
SHUTDOWN
AND DIMMING
CONTROL
C1
1µF
C1, C2: X5R OR X7R DIELECTRIC
L1: MURATA LQH32CN220
Figure 1. Li-Ion Powered Driver for Four White LEDs
10Ω
3465A F01a
C2
0.22µF
82
VIN = 3.6V
80
4 LEDs
78
76
74
72
70
68
EFFICIENCY (%)
66
64
62
60
0
Conversion Efficiency
5
10
LED CURRENT (mA)
15
LT3465
LT3465A
20
3465A F01b
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LT3465/LT3465A
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ABSOLUTE AXI U RATI GS
(Note 1)
Input Voltage (VIN) ................................................. 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
PACKAGE/ORDER I FOR ATIO
V
1
OUT
GND 2
FB 3
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
T
= 125°C, θJA = 256°C/W IN FREE AIR
JMAX
θ
= 120°C ON BOARD OVER GROUND PLANE
JA
UU
TOP VIEW
6 SW
5 V
IN
4 CTRL
W
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART NUMBER
LT3465ES6
LT3465AES6
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
temperature range, otherwise specifications are at T
PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS
Minimum Operating Voltage 2.7 2.7 V
Maximum Operating Voltage 16 16 V
Feedback Voltage 0°C ≤ TA ≤ 85°C 188 200 212 188 200 212 mV
FB Pin Bias Current 10 35 100 10 35 100 nA
Supply Current Not Switching 1.9 2.6 3.3 1.9 2.6 3.3 mA
CTRL = 0V 2.0 3.2 5.0 2.0 3.2 5.0 µA
Switching Frequency 0.8 1.2 1.6 1.8 2.4 2.8 MHz
Maximum Duty Cycle
Switch Current Limit
Switch V
CESAT
Switch Leakage Current VSW = 5V 0.01 5 0.01 5 µA
V
for Full LED Current 1.8 1.8 V
CTRL
V
to Enable Chip
CTRL
V
to Shut Down Chip
CTRL
CTRL Pin Bias Current 48 60 72 48 60 72 µA
Soft-Start Time 600 µs
Schottky Forward Drop ID = 150mA 0.7 0.7 V
Schottky Leakage Current VR = 30V 4 4 µA
ISW = 250mA 300 300 mV
= 85°C 405060405060 µA
T
A
= –40°C 607590607590 µA
T
A
The ● denotes the specifications which apply over the full operating
= 25°C. VIN = 3V, V
A
●
●
●
●
= 3V, unless otherwise noted.
CTRL
LT3465 LT3465A
90 93 90 93 %
225 340 225 340 mA
150 150 mV
50 50 mV
S6 PART MARKING
LTH2
LTAFT
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
2
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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INPUT VOLTAGE (V)
2 2.5
0
INPUT CURRENT (mA)
2
5
3
4
4.5
3465A G06
1
4
3
3.5
5
T
A
= 25°C
TEMPERATURE (°C)
–50
4365A G08
0
50 100
SWITCHING FREQUENCY (MHz)
3.0
2.5
2.0
1.5
1.0
0.5
0
LT3465
LT3465A
TYPICAL PERFOR A CE CHARACTERISTICS
Switch Saturation Voltage (V
450
T
= 25°C
A
400
350
300
250
200
150
100
50
SWITCH SATURATION VOLTAGE (mV)
0
0
100
50
150 350
SWITCH CURRENT (mA)
200
250 300
) Schottky Forward Voltage Drop
CESAT
300
T
= 25°C
A
250
200
150
100
50
SCHOTTKY FORWARD CURRENT (mA)
0
0
3465A G01
400 600 800
200
SCHOTTKY FORWARD DROP (mV)
1000 1200
3465A G02
LT3465/LT3465A
Shutdown Quiescent Current
(CTRL = 0V)
30
T
= 25°C
A
27
24
21
18
15
(µA)
Q
I
12
9
6
3
0
4 6 10 12
2
8
VIN (V)
14
3465A G03
16
VFB vs V
250
200
150
100
FEEDBACK VOLTAGE (mV)
50
0
0
T
CTRL
= 25°C
A
0.5
CONTROL VOLTAGE (V)
Switching Waveforms (LT3465)
V
SW
10V/DIV
I
L
100mA/DIV
V
OUT
100mV/DIV
Open-Circuit Output Clamp Voltage
35
= 25°C
T
A
30
25
20
15
10
OUTPUT CLAMP VOLTAGE (V)
5
1
1.5
2
3465A G04
0
2
46
INPUT VOLTAGE (V)
10 14 16
812
3465A G05
Switching Waveforms (LT3465A)
V
SW
10V/DIV
I
L
50mA/DIV
V
OUT
50mV/DIV
Input Current in Output Open Circuit
Switching Frequency
V
IN
4 LEDs
20mA, 22µH
= 3.6V 200ns/DIV
3465A G07a
V
= 3.6V 100ns/DIV
IN
4 LEDs
20mA, 22µH
3465A G07b
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LT3465/LT3465A
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TYPICAL PERFOR A CE CHARACTERISTICS
Feedback Voltage
210
208
206
204
202
200
198
196
FEEDBACK VOLTAGE (mV)
194
192
190
–50
–30 10
–10
TEMPERATURE (°C)
85
80
75
70
EFFICIENCY (%)
65
60
–50
30
50
V
= 3.6V, 4 LEDs
IN
LT3465
LT3465A
15mA
0
TEMPERATURE (°C)
Quiescent Current (CTRL = 3V)
3.0
2.5
2.0
1.5
(mA)
Q
I
1.0
0.5
0
90
70
3465A G09
0
5101520
VIN (V)
–50°C
25°C
100°C
3465A G10
Switching Current Limit
400
350
300
250
200
150
CURRENT LIMIT (mA)
100
50
0
20 40 80
0
DUTY CYCLE (%)
–50°C
25°C
100°C
60
100
3465A G11
Schottky Leakage Current
8
20mA
10mA
50
100
3465A G12
7
6
5
4
3
2
SCHOTTKY LEAKAGE CURRENT (µA)
1
0
–50
050
TEMPERATURE (°C)
V
= 25
R
V
= 16
R
= 10
V
R
100
3465A G13
4
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LT3465/LT3465A
U
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PI FU CTIO S
V
(Pin 1): Output Pin. Connect to output capacitor and
OUT
LEDs. Minimize trace between this pin and output capacitor 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:
I
LED
⎛
⎜
1
⎜
•–•
200 26 1
=
R
FB
mV mV n
⎜⎜
⎜
⎝
⎛
exp
⎜
⎜
⎜
⎛
ex
pp
⎜
⎜
⎝
⎝
CTRL (Pin 4): Dimming Control and Shutdown Pin. Ground
this pin to shut down the device. When V
than about 1.8V, full-scale LED current is generated.
When V
Floating this pin places the device in shutdown mode.
V
(Pin 5): Input Supply Pin. Must be locally bypassed
IN
with a 1µF X5R or X7R type ceramic capacitor.
SW (Pin 6): Switch Pin. Connect inductor here.
200
mV
⎛
⎜
⎝
26
mV
VmV
()
CTRL
526
•
mV mV
is less than 1V, LED current is reduced.
CTRL
⎞
⎞
⎟
⎠
⎞
⎟
⎟
⎟
⎟
1
+
⎟
⎟
⎞
⎟
⎟
⎟
⎠
⎠
⎠
CTRL
>for V mV
150
is greater
CTRL
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LT3465/LT3465A
BLOCK DIAGRA
W
V
IN
5
V
REF
1.25V
CTRL
4
40k
FB
3
200mV
SW
–
A1
+
+
R
C
C
C
COMPARATOR
–
A2
+
RQ
S
DRIVER
6
Q1
OVERVOLTAGE
PROTECT
V
OUT
1
+
0.2Ω
–
2
GND
3465A F02
10k
Σ
RAMP
GENERATOR
1.2MHz*
OSCILLATOR
*2.4MHz FOR LT3465A
Figure 2. LT3465 Block Diagram
6
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APPLICATIO S I FOR ATIO
LT3465/LT3465A
Operation
The LT3465 uses a constant 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 2. At the start of each oscillator
cycle, the SR latch is set, which turns on the power switch
Q1. A voltage proportional to the switch current is added
to a stabilizing ramp and the resulting sum is fed into the
positive terminal of the PWM comparator A2. When this
voltage exceeds the level at the negative input of A2, the
SR latch is reset turning off the power switch. The level at
the negative input of A2 is set by the error amplifier A1,
and is simply an amplified version of the difference
between the feedback voltage and the reference voltage of
200mV. In this manner, the error amplifier sets the
correct peak current level to keep the output in regulation.
If the error amplifier’s output increases, more current is
delivered to the output; if it decreases, less current is
delivered. The CTRL pin voltage is used to adjust the
reference voltage.
The block diagram for the LT3465A (not
shown) is identical except that the oscillator frequency
is 2.4MHz.
Minimum Output Current
T
he LT3465 can drive a 3-LED string at 1.5mA LED
current without pulse skipping. As current is further
reduced, the device will begin skipping pulses. This will
result in some low frequency ripple, although the LED
current remains regulated on an average basis down to
zero. The photo in Figure 3a details circuit operation
driving three white LEDs at a 1.5mA load. Peak inductor
current is less than 40mA and the regulator operates in
discontinuous mode, meaning the inductor current
reaches zero during the discharge phase. After the inductor current reaches zero, the SW pin exhibits ringing due
to the LC tank circuit formed by the inductor in combination with switch and diode capacitance. This ringing is
not harmful; far less spectral energy is contained in the
ringing than in the switch transitions. The ringing can be
damped by application of a 300Ω resistor across the
inductor, although this will degrade efficiency. Because
of the higher switching frequency, the LT3465A can drive
a 3-LED string at 0.2mA LED current without pulse
V
SW
5V/DIV
I
L
20mA/DIV
V
OUT
10mV/DIV
= 4.2V 0.2µs/DIV
V
IN
I
= 1.5mA
LED
3 LEDs
Figure 3a. Switching Waveforms (LT3465)
V
SW
5V/DIV
I
L
20mA/DIV
V
OUT
10mV/DIV
= 4.2V 0.1µs/DIV
V
IN
I
= 0.2mA
LED
3 LEDs
Figure 3b. Switching Waveforms (LT3465A)
3465A F03a
3465A F03b
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APPLICATIO S I FOR ATIO
skipping using a 1k resistor from FB to GND. The photo
in Figure 3b details circuit operation driving three white
LEDs at a 0.2mA load. Peak inductor current is less
than 30mA.
Inductor Selection
A 22µH inductor is recommended for most LT3465 appli-
cations. Although small size and high efficiency are major
concerns, the inductor should have low core losses at
1.2MHz and low DCR (copper wire resistance). Some
inductors in this category with small size are listed in
Table 1. The efficiency comparison of different inductors
is shown in Figure 4a. A 22µH or 10µH inductor is recom-
mended for most LT3465A applications. The inductor
should have low core losses at 2.4MHz and low DCR. The
efficiency comparison of different inductors is shown in
figure 4b.
Table 1. Recommended Inductors
PART CURRENT RATING
NUMBER DCR (Ω) (mA) MANUFACTURER
LQH32CN220 0.71 250 Murata
LQH2MCN220 2.4 185 814-237-1431
www.murata.com
ELJPC220KF 4.0 160 Panasonic
714-373-7334
www.panasonic.com
CDRH3D16-220 0.53 350 Sumida
847-956-0666
www.sumida.com
LB2012B220M 1.7 75 Taiyo Yuden
408-573-4150
www.t-yuden.com
LEM2520-220 5.5 125 Taiyo Yuden
408-573-4150
www.t-yuden.com
85
VIN = 3.6V
4 LEDs
80
75
70
65
EFFICIENCY (%)
60
55
50
0
MURATA LQH32CN220
TAIYO YUDEN LB2012B220M
TAIYO YUDEN CB2012B220
510 20
LED CURRENT (mA)
15
3465A F04b
Figure 4a. Efficiency Comparison of Different Inductors (LT3465)
80
VIN = 3.6V
4 LEDs
75
70
65
EFFICIENCY (%)
60
55
50
0
MURATA LQH32CN220
MURATA LQH32CN100
MURATA LQH2MCN220
TOKO D312-220
TOKO D312-100
TAIYO YUDEN LB2012B220
510 20
LED CURRENT (mA)
15
3465A F04b
Figure 4b. Efficiency Comparison of Different Inductors (LT3465A)
Capacitor Selection
The small size of ceramic capacitors makes them ideal for
LT3465 and LT3465A applications. X5R and X7R types are
recommended because they retain their capacitance over
wider voltage and temperature ranges than other types
such as Y5V or Z5U. A 1µF input capacitor and a 0.22µF
output capacitor are sufficient for most LT3465 and
LT3465A applications.
8
Table 2. Recommended Ceramic Capacitor Manufacturers
MANUFACTURER PHONE URL
Taiyo Yuden 408-573-4150 www.t-yuden.com
Murata 814-237-1431 www.murata.com
Kemet 408-986-0424 www.kemet.com
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APPLICATIO S I FOR ATIO
LT3465/LT3465A
Soft-Start (LT3465)
The LT3465 has an internal soft-start circuit to limit the
input current during circuit start-up. The circuit start-up
waveforms are shown in Figure 5.
IIN 50mA/DIV
5V/DIV
V
OUT
100mV/DIV
V
FB
CTRL 5V/DIV
= 3.6V 200µs/DIV
V
IN
4 LEDs, 20mA
L = 22µH
C = 0.22µF
Figure 5. Start-Up Waveforms
3465 F05
Inrush Current
The LT3465 and LT3465A have a built-in Schottky diode.
When supply voltage is applied to the V
difference between V
and V
IN
generates inrush current
OUT
pin, the voltage
IN
flowing from input through the inductor and the Schottky
diode to charge the output capacitor to V
. The maximum
IN
current the Schottky diode in the LT3465 and LT3465A
can sustain is 1A. The selection of inductor and capacitor
value should ensure the peak of the inrush current to be
below 1A. The peak inrush current can be calculated
as follows:
⎡
06
–.
V
IN
I
=
α
ω
P
=
=
L
+
r
2
LC
•
15
.
•
L
1
•
ω
–
⎡
+
4
⎢
⎢
⎣
.
15
•
L
α
ω
2
2
• exp – • arctan • sin arctan
r
()
⎤
⎞
⎛
ω
⎟
⎜
α
⎠
⎝
⎢
⎥
⎢
⎥
⎣
⎦
⎤
⎞
⎛
ω
⎥
⎟
⎜
α
⎠
⎝
⎥
⎦
where L is the inductance, r is the resistance of the
inductor and C is the output capacitance. For low DCR
inductors, which is usually the case for this application,
the peak inrush current can be simplified as follows:
αωπ
⎞
⎟
2ω
⎠
–.
06
V
IN
I
=
P
•
L
⎛
• exp – •
⎜
⎝
Table 3 gives inrush peak currents for some component
selections.
Table 3. Inrush Peak Current
VIN (V) r (Ω)L (µH) C (µF) IP (A)
5 0.5 22 0.22 0.38
5 0.5 22 1 0.70
3.6 0.5 22 0.22 0.26
5 0.5 33 1 0.60
LED Current and Dimming Control
The LED current is controlled by the feedback resistor (R1
in Figure 1) and the feedback reference voltage.
I
= VFB/R
LED
FB
The CTRL pin controls the feedback reference voltage as
shown in the Typical Performance Characteristics. For
CTRL higher than 1.8V, the feedback reference is 200mV,
which results in full LED current. CTRL pin can be used as
dimming control when CTRL voltage is between 200mV to
1.5V. In order to have accurate LED current, precision
resistors are preferred (1% is recommended). The formula and table for R
RFB = 200mV/I
Table 4. RFB Resistor Value Selection
FULL I
(mA) R1 (Ω)
LED
5 40.0
10 20.0
15 13.3
20 10.0
selection are shown below.
FB
LED-Full
(1)
The filtered PWM signal can be considered to be an
adjustable DC voltage. It can be used to adjust the CTRL
voltage source in dimming control. The circuit is shown in
Figure 6. The corner frequency of R1 and C1 should be
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APPLICATIO S I FOR ATIO
lower than the frequency of the PWM signal. R1 needs to
be much smaller than the internal impedance in the CTRL
pin, which is 50kΩ. A 5k resistor is suggested.
C1
100nF
LT3465/
LT3465A
CTRL
3465A F06
R1
PWM
Figure 6. Dimming Control Using a Filtered PWM Signal
5k
Dimming Using Direct PWM (LT3465A)
Unlike the LT3465, the LT3465A does not have internal
soft-start. Although the input current is higher during
start-up, the absence of soft-start allows the CTRL pin to
be directly driven with a PWM signal for dimming. A zero
LT3465A
PWM
CTRL
percent duty cycle sets the LED current to zero, while
100% duty cycle sets it to full current. Average LED
current increases proportionally with the duty cycle of the
PWM signal. With the PWM signal at the CTRL pin to turn
the LT3465A on and off, the output capacitor is charged
and discharged accordingly. This capacitor charging/
discharging affects the waveform at the FB pin. For low
PWM frequencies the output capacitor charging/discharging time is a very small portion in a PWM period. The
average FB voltage increases linearly with the PWM duty
cycle. As the PWM frequency increases, the capacitor
charging/discharging has a larger effect on the linearity of
the PWM control. Waveforms for a 1kHz and 10kHz PWM
CTRL signals are shown in Figures 7a and 7b respectively.
The capacitor charging/discharging has a larger effect on
the FB waveform in the 10kHz case than that in the 1kHz
100mV/DIV
CTRL
2V/DIV
100mV/DIV
CTRL
2V/DIV
FB
200µs/DIV (1kHz)
Figure 7a.
FB
20µs/DIV (10kHz)
Figure 7b.
3465A F07a
3465A F07b
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APPLICATIO S I FOR ATIO
LT3465/LT3465A
case. The Average FB Voltage vs PWM Duty Cycle curves
of different PWM frequencies with different output capacitors are shown in Figures 7c and 7d respectively. For
PWM frequency lower than 1kHz, the curves are almost
linear. For PWM frequency higher than 10kHz, the curves
show strong nonlinearity. Since the cause of the
nonlinearity is the output capacitor charging/discharging, the output capacitance and output voltage also affect
200
C
= 0.22µF
OUT
180
4 LEDs
160
140
120
100
80
80
10Hz
100Hz
1kHz
10kHz
30kHz
100
3465A F07c
60
40
AVERAGE FEEDBACK VOLTAGE (mV)
20
0
20
0
CTRL PWM DUTY CYCLE (%)
60
40
the nonlinearity in the high PWM frequencies. Because
smaller capacitance corresponds to shorter capacitor
charging/discharging time, the smaller output capacitance has better linearity as shown in Figures 7c and 7d.
Figures 7e and 7f show the output voltage’s effect to the
curves. The PWM signal should be at least 1.8V in
magnitude; lower voltage will lower the feedback voltage
as shown in Equation 1.
200
C
= 0.47µF
OUT
180
4 LEDs
160
140
120
100
80
80
10Hz
100Hz
1kHz
10kHz
30kHz
100
3465A F07d
60
40
AVERAGE FEEDBACK VOLTAGE (mV)
20
0
2010 30 50 70 90
0
40
CTRL PWM DUTY CYCLE (%)
60
Figure 7c. VFB vs CTRL PWM Duty Cycle Figure 7d. VFB vs CTRL PWM Duty Cycle
200
10kHz PWM
180
160
140
120
100
AVERAGE FEEDBACK VOLTAGE (mV)
= 0.22µF
C
OUT
80
60
80
2 LEDs
3 LEDs
4 LEDs
100
3465A F07e
40
20
0
20
0
CTRL PWM DUTY CYCLE (%)
60
40
Figure 7e.VFB vs CTRL PWM Duty Cycle
200
30kHz PWM
180
160
140
120
100
AVERAGE FEEDBACK VOLTAGE (mV)
Figure 7f.V
= 0.22µF
C
OUT
80
60
40
20
0
20
0
40
CTRL PWM DUTY CYCLE (%)
vs CTRL PWM Duty Cycle
FB
2 LEDs
3 LEDs
4 LEDs
60
80
100
3465A F07f
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11
LT3465/LT3465A
WUUU
APPLICATIO S I FOR ATIO
Open-Circuit Protection
The LT3465 and LT3465A have an internal open-circuit
protection circuit. In the cases of output open circuit,
when the LEDs are disconnected from the circuit or the
LEDs fail, the V
is clamped at 30V. The LT3465 and
OUT
LT3465A will then switch at a very low frequency to
minimize the input current. V
and input current during
OUT
output open circuit are shown in the Typical Performance
Characteristics.
Board Layout Consideration
As with all switching regulators, careful attention must be
paid to the PCB board layout and component placement.
To maximize efficiency, switch rise and fall times are
made as short as possible. To prevent electromagnetic
interference (EMI) problems, proper layout of the high
frequency switching path is essential. Place C
the V
and GND pins. Always use a ground plane under
OUT
OUT
next to
the switching regulator to minimize interplane coupling.
In addition, the ground connection for the feedback
resistor R1 should be tied directly to the GND pin and not
shared with any other component, ensuring a clean, noisefree connection. Recommended component placement is
shown in Figure 8.
Start-Up Input Current (LT3465A)
As previously mentioned, the LT3465A does not have an
internal soft-start circuit. Inrush current can therefore rise
to approximately 400mA as shown in Figure 9 when
driving 4 LEDs. The LT3465 has an internal soft-start
circuit and is recommended if inrush current must be
minimized.
I
IN
200mV/DIV
FB
200mV/DIV
CTRL
2V/DIV
50µs/DIV
3465A F09
GND
C
OUT
Figure 8. Recommended Component Placement.
1
2
3
R
FB
L
6
5
4
3465A F08a
C
IN
V
IN
CTRL
Figure 9.
12
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TYPICAL APPLICATIO S
LT3465/LT3465A
U
Li-Ion to Two White LEDs
3V TO 5V
3V TO 5V
L1
22µH
SW V
IN
LT3465/
LT3465A
GND
SW V
V
IN
LT3465/
LT3465A
CTRL
GND
OUT
FB
OUT
C
IN
1µF
C
: TAIYO YUDEN JMK107BJ105
IN
: AVX 0603ZD105
C
OUT
L1: MURATA LQH32CN220
C
IN
1µF
CIN: TAIYO YUDEN JMK107BJ105
: AVX 0603YD224
C
OUT
L1: MURATA LQH32CN220
V
CTRL
L1
22µH
85
VIN = 3.6V
2 LEDs
80
75
70
65
EFFICIENCY (%)
60
55
50
0
10
20
LED CURRENT (mA)
LT3465
LT3465A
30
40
50
3465A TA01b
R1
4Ω
C
OUT
1µF
3465A TA01a
Li-Ion to Three White LEDs
85
VIN = 3.6V
3 LEDs
80
75
C
OUT
0.22µF
FB
R1
10Ω
3465A TA02a
70
65
EFFICIENCY (%)
60
55
50
0
5
10
LED CURRENT (mA)
15
LT3465
LT3465A
20
3465A TA02b
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13
LT3465/LT3465A
TYPICAL APPLICATIO
U
Li-Ion to Five White LEDs
3V TO 5V
L1
22µH
SW V
OUT
V
C
IN
1µF
CIN: TAIYO YUDEN JMK107BJ105
: TAIYO YUDEN GMK212BJ224
C
OUT
L1: MURATA LQH32CN220
IN
CTRL
LT3465/
LT3465A
GND
FB
R1
10Ω
C
OUT
0.22µF
3465A TA03a
85
VIN = 3.6V
5 LEDs
80
75
70
65
EFFICIENCY (%)
60
55
50
0
5
10
LED CURRENT (mA)
15
LT3465
LT3465A
3465A TA03b
20
14
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PACKAGE DESCRIPTIO
LT3465/LT3465A
U
S6 Package
6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
0.62
MAX
3.85 MAX
2.62 REF
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.20 BSC
DATUM ‘A’
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
0.95
REF
1.22 REF
1.4 MIN
0.30 – 0.50 REF
2.80 BSC
0.09 – 0.20
(NOTE 3)
1.50 – 1.75
(NOTE 4)
1.00 MAX
0.95 BSC
0.80 – 0.90
PIN ONE ID
2.90 BSC
(NOTE 4)
1.90 BSC
0.30 – 0.45
6 PLCS (NOTE 3)
0.01 – 0.10
S6 TSOT-23 0302
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15
LT3465/LT3465A
TYPICAL APPLICATIO
U
Li-Ion to Six White LEDs
85
VIN = 3.6V
6 LEDs
80
75
70
65
EFFICIENCY (%)
60
55
50
0
5
10
LED CURRENT (mA)
15
LT3465
LT3465A
20
3465A TA04b
3V TO 5V
L1
47µH/22µH
SW V
IN
LT3465/
LT3465A
GND
OUT
FB
C
IN
1µF
CIN: TAIYO YUDEN JMK107BJ105
: TAIYO YUDEN GMK212BJ474
C
OUT
L1: MURATA LQH32CN470 (LT3465)
L1: MURATA LQH32CN220 (LT3465A)
V
CTRL
R1
10Ω
C
OUT
0.47µF
3465A TA04a
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I
SHDN
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I
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: 34V, IQ: 1.2mA,
: 34V, IQ: 1.9mA,
: <1µA,
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: <1µA,
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: 0.8V, IQ: 20µA, I
: 0.6V, IQ: 20µA,
: 0.6V, IQ: 40µA,
: 0.8V, IQ: 60µA,
: 0.8V, IQ: 60µA,
: 2.5V, IQ: 25µA,
SHDN
: <1µA,
16
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
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LT/LT 0805 REV A • PRINTED IN USA
© LINEAR TECHNOLOGY CORPORATION 2005
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