LT3465ES6#TRPBF [Linear]
LT3465 - 1.2MHz White LED Step-Up Converters with Built-In Schottky in ThinSOT; Package: SOT; Pins: 6; Temperature Range: -40°C to 85°C;
| 型号： | LT3465ES6#TRPBF |
| 厂家： | 
Linear |
| 描述： | LT3465 - 1.2MHz White LED Step-Up Converters with Built-In Schottky in ThinSOT; Package: SOT; Pins: 6; Temperature Range: -40°C to 85°C 开关 光电二极管 |
| 文件： | 总16页 (文件大小：323K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT3465/LT3465A
1.2MHz/2.4MHz White
LED Drivers with Built-in
Schottky in ThinSOT
U
DESCRIPTIO
FEATURES
The LT®3465/LT3465A are step-up DC/DC converters
designedtodriveuptosixLEDsinseriesfromaLi-Ioncell.
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.
■
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
■
VOUT(MAX) = 30V
■
Automatic Soft-Start (LT3465)
■
Open LED Protection
The LT3465 switches at 1.2MHz, allowing the use of tiny
external components. The faster LT3465A switches at
2.4MHz. Constantfrequencyswitchingresultsinlowinput
noise and a small output capacitor. Just 0.22µF is required
for 3-, 4- or 5-LED applications.
■
High Efficiency: 81% (LT3465) 79% (LT3465A)
Typical
■
Requires Only 0.22µF Output Capacitor
■
Low Profile (1mm) SOT-23
U
The LT3465 and LT3465A are available in the low profile
APPLICATIO S
(1mm) 6-lead SOT-23 (ThinSOTTM) package.
■
Cellular Phones
, 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.
■
PDAs, Handheld Computers
■
Digital Cameras
■
MP3 Players
■
GPS Receivers
U
TYPICAL APPLICATIO
Conversion Efficiency
L1
82
22µH
V
= 3.6V
IN
80
78
76
74
72
70
68
66
64
62
60
4 LEDs
3V TO 5V
SW
V
OUT
V
IN
C1
1µF
C2
0.22µF
LT3465/
LT3465A
CTRL
GND
SHUTDOWN
AND DIMMING
CONTROL
FB
10Ω
3465A F01a
C1, C2: X5R OR X7R DIELECTRIC
L1: MURATA LQH32CN220
LT3465
LT3465A
10
0
5
15
20
Figure 1. Li-Ion Powered Driver for Four White LEDs
LED CURRENT (mA)
3465A F01b
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LT3465/LT3465A
W W
U W
U W
U
ABSOLUTE AXI U RATI GS
(Note 1)
PACKAGE/ORDER I FOR ATIO
TOP VIEW
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
Lead Temperature (Soldering, 10 sec)................. 300°C
V
1
6 SW
OUT
GND 2
FB 3
5 V
IN
4 CTRL
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
TJMAX = 125°C, θJA = 256°C/W IN FREE AIR
= 120°C ON BOARD OVER GROUND PLANE
θ
JA
S6 PART MARKING
ORDER PART NUMBER
LT3465ES6
LT3465AES6
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
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T = 25°C. V = 3V, V
= 3V, unless otherwise noted.
A
IN
CTRL
LT3465
TYP
LT3465A
TYP
PARAMETER
CONDITIONS
MIN
MAX
MIN
MAX
UNITS
V
Minimum Operating Voltage
Maximum Operating Voltage
Feedback Voltage
2.7
2.7
16
16
V
0°C ≤ T ≤ 85°C
188
10
200
35
212
100
188
10
200
35
212
100
mV
nA
A
FB Pin Bias Current
Supply Current
Not Switching
CTRL = 0V
1.9
2.0
2.6
3.2
3.3
5.0
1.9
2.0
2.6
3.2
3.3
5.0
mA
µA
Switching Frequency
Maximum Duty Cycle
Switch Current Limit
0.8
90
1.2
93
1.6
1.8
90
2.4
93
2.8
MHz
%
●
●
225
340
300
0.01
225
340
300
0.01
mA
mV
µA
Switch V
I
= 250mA
= 5V
CESAT
SW
Switch Leakage Current
V
5
5
SW
V
V
V
for Full LED Current
to Enable Chip
1.8
1.8
V
CTRL
CTRL
CTRL
●
●
150
150
mV
mV
to Shut Down Chip
50
50
CTRL Pin Bias Current
48
40
60
60
50
75
72
60
90
48
40
60
60
50
75
72
60
90
µA
µA
µA
T = 85°C
A
A
T = –40°C
Soft-Start Time
600
0.7
µs
V
Schottky Forward Drop
Schottky Leakage Current
I = 150mA
0.7
D
V = 30V
R
4
4
µA
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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LT3465/LT3465A
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TYPICAL PERFOR A CE CHARACTERISTICS
Shutdown Quiescent Current
(CTRL = 0V)
Switch Saturation Voltage (V
)
Schottky Forward Voltage Drop
CESAT
450
400
350
300
250
200
150
100
50
300
250
200
150
100
50
30
27
24
21
18
15
12
9
T
= 25°C
T
= 25°C
T
= 25°C
A
A
A
6
3
0
0
0
0
400
600
800
1000 1200
4
6
10
(V)
12
0
50 100 150
350
200
2
14
16
200 250 300
8
V
SCHOTTKY FORWARD DROP (mV)
SWITCH CURRENT (mA)
IN
3465A G02
3465A G01
3465A G03
V
vs V
Open-Circuit Output Clamp Voltage
Input Current in Output Open Circuit
FB
CTRL
5
4
3
2
1
0
250
200
150
100
50
35
30
T
= 25°C
T
= 25°C
T
A
= 25°C
A
A
25
20
15
10
5
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0
2
10
INPUT VOLTAGE (V)
14
16
2
4
6
8
12
INPUT VOLTAGE (V)
CONTROL VOLTAGE (V)
3465A G04
3465A G06
3465A G05
Switching Waveforms (LT3465)
Switching Frequency
Switching Waveforms (LT3465A)
3.0
2.5
2.0
1.5
1.0
0.5
0
VSW
VSW
10V/DIV
10V/DIV
LT3465A
IL
IL
100mA/DIV
50mA/DIV
VOUT
100mV/DIV
VOUT
50mV/DIV
LT3465
V
IN = 3.6V
200ns/DIV
3465A G07a
V
IN = 3.6V
100ns/DIV
3465A G07b
4 LEDs
4 LEDs
20mA, 22µH
20mA, 22µH
50
TEMPERATURE (°C)
100
–50
0
4365A G08
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LT3465/LT3465A
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TYPICAL PERFOR A CE CHARACTERISTICS
Quiescent Current (CTRL = 3V)
Switching Current Limit
Feedback Voltage
3.0
2.5
210
208
206
204
202
200
198
196
194
192
190
400
350
300
250
2.0
1.5
200
150
1.0
0.5
0
100
50
0
–50°C
–50°C
25°C
100°C
25°C
100°C
0
5
10
(V)
15
20
–50
70
90
0
20
40
DUTY CYCLE (%)
60
80
100
–30 –10 10
30
TEMPERATURE (°C)
50
V
IN
3465A G10
3465A G09
3465A G11
V
IN
= 3.6V, 4 LEDs
Schottky Leakage Current
85
80
75
70
65
60
8
7
6
5
LT3465
LT3465A
20mA
V
= 25
R
V
= 16
= 10
R
V
R
15mA
4
3
10mA
2
1
0
50
100
0
50
–50
0
–50
100
TEMPERATURE (°C)
TEMPERATURE (°C)
3465A G12
3465A G13
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LT3465/LT3465A
U
U
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PI FU CTIO S
VOUT (Pin 1): Output Pin. Connect to output capacitor and CTRL(Pin4):DimmingControlandShutdownPin.Ground
LEDs. Minimize trace between this pin and output capaci- this pin to shut down the device. When VCTRL is greater
tor to reduce EMI.
than about 1.8V, full-scale LED current is generated.
When VCTRL is less than 1V, LED current is reduced.
Floating this pin places the device in shutdown mode.
GND (Pin 2): Ground Pin. Connect directly to local ground
plane.
VIN (Pin 5): Input Supply Pin. Must be locally bypassed
with a 1µF X5R or X7R type ceramic capacitor.
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:
SW (Pin 6): Switch Pin. Connect inductor here.
⎛
⎜
⎞
⎛
⎞
⎟
200mV
26mV
⎛
⎞
exp
⎟
⎟
⎜
⎜
⎜
⎜
⎝
⎟
⎠
1
RFB
⎜
⎟
ILED
=
• 200mV – 26mV • 1n
+ 1 for VCTRL > 150mV
⎜
⎜
⎝
⎟
⎟
⎠
⎟
⎛
⎞
VCTRL mV
(
)
exp
⎜
⎝
⎟
⎠
⎜
⎟
5mV • 26mV
⎝
⎠
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LT3465/LT3465A
W
BLOCK DIAGRA
V
IN
FB
3
5
6
SW
V
OUT
1
–
+
+
COMPARATOR
A2
200mV
–
+
V
REF
A1
DRIVER
1.25V
Q1
R
Q
R
C
S
OVERVOLTAGE
PROTECT
C
C
+
–
0.2Ω
Σ
10k
RAMP
GENERATOR
CTRL
4
40k
2
GND
3465A F02
1.2MHz*
OSCILLATOR
*2.4MHz FOR LT3465A
Figure 2. LT3465 Block Diagram
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LT3465/LT3465A
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APPLICATIO S I FOR ATIO
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Operation
Minimum Output Current
he LT3465 can drive a 3-LED string at 1.5mA LED
The LT3465 uses a constant frequency, current mode
control scheme to provide excellent line and load regula-
tion. 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
betweenthefeedbackvoltageandthereferencevoltageof
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
referencevoltage. TheblockdiagramfortheLT3465A(not
shown) is identical except that the oscillator frequency
is 2.4MHz.
T
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
reacheszeroduringthedischargephase.Aftertheinduc-
tor current reaches zero, the SW pin exhibits ringing due
to the LC tank circuit formed by the inductor in combina-
tion 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
ofthehigherswitchingfrequency,theLT3465Acandrive
a 3-LED string at 0.2mA LED current without pulse
VSW
5V/DIV
IL
20mA/DIV
VOUT
10mV/DIV
VIN = 4.2V
ILED = 1.5mA
3 LEDs
0.2µs/DIV
3465A F03a
Figure 3a. Switching Waveforms (LT3465)
VSW
5V/DIV
IL
20mA/DIV
VOUT
10mV/DIV
VIN = 4.2V
ILED = 0.2mA
3 LEDs
0.1µs/DIV
3465A F03b
Figure 3b. Switching Waveforms (LT3465A)
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LT3465/LT3465A
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APPLICATIO S I FOR ATIO
85
80
75
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.
V
= 3.6V
IN
4 LEDs
70
65
60
55
50
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.
MURATA LQH32CN220
TAIYO YUDEN LB2012B220M
TAIYO YUDEN CB2012B220
5
10
20
0
15
LED CURRENT (mA)
3465A F04b
Figure 4a. Efficiency Comparison of Different Inductors (LT3465)
80
V
= 3.6V
IN
4 LEDs
75
70
65
60
55
50
Table 1. Recommended Inductors
PART
NUMBER
CURRENT RATING
(mA)
DCR (Ω)
MANUFACTURER
LQH32CN220
LQH2MCN220
0.71
2.4
250
185
Murata
814-237-1431
www.murata.com
MURATA LQH32CN220
MURATA LQH32CN100
MURATA LQH2MCN220
TOKO D312-220
TOKO D312-100
TAIYO YUDEN LB2012B220
ELJPC220KF
4.0
0.53
1.7
160
350
75
Panasonic
714-373-7334
www.panasonic.com
5
10
20
0
15
LED CURRENT (mA)
CDRH3D16-220
LB2012B220M
LEM2520-220
Sumida
847-956-0666
www.sumida.com
3465A F04b
Figure 4b. Efficiency Comparison of Different Inductors (LT3465A)
Taiyo Yuden
408-573-4150
www.t-yuden.com
Capacitor Selection
5.5
125
Taiyo Yuden
408-573-4150
www.t-yuden.com
The small size of ceramic capacitors makes them ideal for
LT3465andLT3465Aapplications.X5RandX7Rtypesare
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.
Table 2. Recommended Ceramic Capacitor Manufacturers
MANUFACTURER
Taiyo Yuden
Murata
PHONE
URL
408-573-4150
814-237-1431
408-986-0424
www.t-yuden.com
www.murata.com
www.kemet.com
Kemet
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LT3465/LT3465A
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APPLICATIO S I FOR ATIO
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Soft-Start (LT3465)
inductors, which is usually the case for this application,
the peak inrush current can be simplified as follows:
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.
⎛
⎞
⎟
V – 0.6
α π
IN
IP =
• exp –
•
⎜
L • ω
ω 2
⎝
⎠
Table 3 gives inrush peak currents for some component
selections.
IIN 50mA/DIV
VOUT 5V/DIV
Table 3. Inrush Peak Current
V
(V)
r (Ω)
0.5
L (µH)
22
C (µF)
0.22
1
I (A)
IN
P
VFB 100mV/DIV
CTRL 5V/DIV
5
0.38
0.70
0.26
0.60
5
3.6
5
0.5
22
VIN = 3.6V
4 LEDs, 20mA
L = 22µH
200µs/DIV
3465 F05
0.5
22
0.22
1
0.5
33
C = 0.22µF
Figure 5. Start-Up Waveforms
LED Current and Dimming Control
The LED current is controlled by the feedback resistor (R1
in Figure 1) and the feedback reference voltage.
Inrush Current
The LT3465 and LT3465A have a built-in Schottky diode.
When supply voltage is applied to the VIN pin, the voltage
difference between VIN and VOUT generates inrush current
flowing from input through the inductor and the Schottky
diode to charge the output capacitor to VIN. The maximum
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:
ILED = VFB/RFB
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
dimmingcontrolwhenCTRLvoltageisbetween200mVto
1.5V. In order to have accurate LED current, precision
resistors are preferred (1% is recommended). The for-
mula and table for RFB selection are shown below.
RFB = 200mV/ILED-Full
(1)
⎡
⎤
⎥
⎡
⎤
⎥
⎛ ⎞
ω
α
⎝ ⎠
⎛ ⎞
ω
α
⎝ ⎠
V – 0.6
L • ω
α
ω
Table 4. R Resistor Value Selection
IN
FB
IP =
α =
• exp – • arctan
• sin arctan
⎢
⎢
⎜ ⎟
⎜ ⎟
FULL I (mA)
R1 (Ω)
40.0
LED
⎢
⎣
⎥
⎢
⎣
⎥
⎦
⎦
5
r + 1.5
2 •L
10
15
20
20.0
13.3
2
10.0
r + 1.5
(
)
1
–
ω =
4 •L2
L •C
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
where L is the inductance, r is the resistance of the
inductor and C is the output capacitance. For low DCR
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LT3465/LT3465A
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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.
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
PWMfrequenciestheoutputcapacitorcharging/discharg-
ing 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
CTRLsignalsareshowninFigures7aand7brespectively.
The capacitor charging/discharging has a larger effect on
the FB waveform in the 10kHz case than that in the 1kHz
LT3465/
R1
5k
LT3465A
CTRL
PWM
C1
100nF
3465A F06
Figure 6. Dimming Control Using a Filtered PWM Signal
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
CTRL
PWM
FB
100mV/DIV
CTRL
2V/DIV
200µs/DIV (1kHz)
3465A F07a
Figure 7a.
FB
100mV/DIV
CTRL
2V/DIV
20µs/DIV (10kHz)
3465A F07b
Figure 7b.
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LT3465/LT3465A
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APPLICATIO S I FOR ATIO
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case. The Average FB Voltage vs PWM Duty Cycle curves
of different PWM frequencies with different output ca-
pacitors 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/discharg-
ing, the output capacitance and output voltage also affect
the nonlinearity in the high PWM frequencies. Because
smaller capacitance corresponds to shorter capacitor
charging/discharging time, the smaller output capaci-
tance 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
200
C
= 0.47µF
C
= 0.22µF
OUT
OUT
4 LEDs
180
160
140
120
100
80
180
160
140
120
100
80
4 LEDs
10Hz
100Hz
1kHz
10kHz
30kHz
10Hz
100Hz
1kHz
10kHz
30kHz
60
60
40
40
20
20
0
0
0
10 20 30 40 50 60 70 80 90 100
CTRL PWM DUTY CYCLE (%)
3465A F07d
0
20
40
60
80
100
CTRL PWM DUTY CYCLE (%)
3465A F07c
Figure 7c. V vs CTRL PWM Duty Cycle
Figure 7d. V vs CTRL PWM Duty Cycle
FB
FB
200
180
160
140
120
100
80
200
30kHz PWM
OUT
10kHz PWM
OUT
180
C
= 0.22µF
C
= 0.22µF
160
140
120
100
80
60
60
2 LEDs
3 LEDs
4 LEDs
2 LEDs
3 LEDs
4 LEDs
40
40
20
20
0
0
0
20
40
60
80
100
0
20
40
60
80
100
CTRL PWM DUTY CYCLE (%)
CTRL PWM DUTY CYCLE (%)
3465A F07f
3465A F07e
Figure 7f.V vs CTRL PWM Duty Cycle
Figure 7e.V vs CTRL PWM Duty Cycle
FB
FB
3465afa
11
LT3465/LT3465A
W U U
U
APPLICATIO S I FOR ATIO
Open-Circuit Protection
resistor R1 should be tied directly to the GND pin and not
sharedwithanyothercomponent,ensuringaclean,noise-
free connection. Recommended component placement is
shown in Figure 8.
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 VOUT is clamped at 30V. The LT3465 and
LT3465A will then switch at a very low frequency to
minimize the input current. VOUT and input current during
output open circuit are shown in the Typical Performance
Characteristics.
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.
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 COUT next to
the VOUT and GND pins. Always use a ground plane under
the switching regulator to minimize interplane coupling.
In addition, the ground connection for the feedback
IIN
200mV/DIV
FB
200mV/DIV
CTRL
2V/DIV
50µs/DIV
3465A F09
Figure 9.
GND
L
1
2
3
6
5
4
C
C
IN
OUT
V
IN
R
FB
CTRL
3465A F08a
Figure 8. Recommended Component Placement.
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12
LT3465/LT3465A
U
TYPICAL APPLICATIO S
Li-Ion to Two White LEDs
85
L1
22µH
V
= 3.6V
IN
2 LEDs
3V TO 5V
80
75
SW
V
OUT
V
70
65
60
55
50
IN
C
C
OUT
IN
1µF
LT3465/
LT3465A
CTRL
GND
1µF
FB
R1
4Ω
3465A TA01a
LT3465
LT3465A
C
C
: TAIYO YUDEN JMK107BJ105
IN
: AVX 0603ZD105
OUT
L1: MURATA LQH32CN220
0
10
20
30
40
50
LED CURRENT (mA)
3465A TA01b
Li-Ion to Three White LEDs
85
L1
22µH
V
= 3.6V
IN
3 LEDs
80
75
3V TO 5V
SW
V
OUT
V
70
65
60
55
50
IN
C
C
IN
1µF
OUT
0.22µF
LT3465/
LT3465A
CTRL
GND
FB
R1
10Ω
3465A TA02a
LT3465
LT3465A
C
C
: TAIYO YUDEN JMK107BJ105
IN
: AVX 0603YD224
OUT
L1: MURATA LQH32CN220
0
5
10
15
20
LED CURRENT (mA)
3465A TA02b
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13
LT3465/LT3465A
U
TYPICAL APPLICATIO
Li-Ion to Five White LEDs
L1
85
80
75
70
65
60
55
50
V
= 3.6V
IN
5 LEDs
22µH
3V TO 5V
SW
V
OUT
V
IN
C
C
IN
1µF
OUT
0.22µF
LT3465/
LT3465A
CTRL
GND
FB
R1
10Ω
LT3465
3465A TA03a
LT3465A
C
C
: TAIYO YUDEN JMK107BJ105
IN
: TAIYO YUDEN GMK212BJ224
0
5
10
15
20
OUT
L1: MURATA LQH32CN220
LED CURRENT (mA)
3465A TA03b
3465afa
14
LT3465/LT3465A
U
PACKAGE DESCRIPTIO
S6 Package
6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
2.90 BSC
(NOTE 4)
0.62
MAX
0.95
REF
1.22 REF
1.4 MIN
1.50 – 1.75
2.80 BSC
3.85 MAX 2.62 REF
(NOTE 4)
PIN ONE ID
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
0.30 – 0.45
6 PLCS (NOTE 3)
0.95 BSC
0.80 – 0.90
0.20 BSC
DATUM ‘A’
0.01 – 0.10
1.00 MAX
0.30 – 0.50 REF
1.90 BSC
0.09 – 0.20
(NOTE 3)
S6 TSOT-23 0302
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
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15
LT3465/LT3465A
U
TYPICAL APPLICATIO
Li-Ion to Six White LEDs
85
80
75
70
65
60
55
50
L1
V
= 3.6V
IN
47µH/22µH
6 LEDs
3V TO 5V
SW
V
OUT
V
IN
C
C
IN
1µF
OUT
0.47µF
LT3465/
LT3465A
CTRL
GND
FB
R1
10Ω
3465A TA04a
LT3465
C
C
: TAIYO YUDEN JMK107BJ105
: TAIYO YUDEN GMK212BJ474
L1: MURATA LQH32CN470 (LT3465)
L1: MURATA LQH32CN220 (LT3465A)
IN
LT3465A
OUT
0
5
10
15
20
LED CURRENT (mA)
3465A TA04b
RELATED PARTS
PART NUMBER DESCRIPTION
COMMENTS
LT1618
Constant Current, Constant Voltage, 1.4MHz, High Efficiency Up to 16 White LEDs, V : 1.6V to 18V, V
: 34V, I : 1.8mA,
OUT(MAX) Q
IN
Boost Regulator
I
: <1µA, 10-Lead MS Package
SHDN
LT1932
Constant Current, 1.2MHz, High Efficiency White LED
Boost Regulator
Up to 8 White LEDs, V : 1V to 10V, V
SHDN
: 34V, I : 1.2mA,
OUT(MAX) Q
IN
I
: <1µA, ThinSOT Package
LT1937
Constant Current, 1.2MHz, High Efficiency White LED
Boost Regulator
Up to 4 White LEDs, V : 2.5V to 10V, V
SHDN
: 34V, I : 1.9mA,
IN
OUT(MAX)
Q
I
: <1µA, ThinSOT
LTC®3200-5
LTC3202
LTC3205
Low Noise, 2MHz, Regulated Charge Pump White LED Driver Up to 6 White LEDs, V : 2.7V to 4.5V, I : 8mA, I
: <1µA,
IN
Q
SHDN
ThinSOT Package
Low Noise, 1.5MHz, Regulated Charge Pump White LED Driver Up to 8 White LEDs, V : 2.7V to 4.5V, I : 5mA, I : <1µA,
SHDN
IN
Q
10-Lead MS Package
Multi-Display LED Controller
92% Efficiency, V : 2.8V to 4.5V, I : 4.2mA, I : <1µA, Drives Main,
IN
Q
SD
Sub, RGB, QFN Package
LTC3405
LTC3405A
300mA (I ), 1.5MHz Synchronous Step-Down
95% Efficiency, V : 2.7V to 6V, V
: 0.8V, I : 20µA, I : <1µA,
SHDN
OUT
IN
OUT(MIN)
Q
DC/DC Converter
ThinSOT Package
LTC3406
600mA (I ), 1.5MHz Synchronous Step-Down
95% Efficiency, V : 2.5V to 5.5V, V
: 0.6V, I : 20µA,
Q
OUT
IN
OUT(MIN)
OUT(MIN)
OUT(MIN)
OUT(MIN)
OUT(MIN)
LTC3406B
DC/DC Converter
I
: <1µA, ThinSOT Package
SHDN
LTC3407
LTC3411
LTC3412
Dual 600mA (I ), 1.5MHz Synchronous Step-Down
95% Efficiency, V : 2.5V to 5.5V, V
: 0.6V, I : 40µA,
Q
OUT
IN
DC/DC Converters
I
: <1µA, MS10E, DFN Package
SHDN
1.25A (I ), 4MHz Synchronous Step-Down DC/DC Converter 95% Efficiency, V : 2.5V to 5.5V, V
: 0.8V, I : 60µA,
Q
OUT
IN
I
: <1µA, MS10, DFN Package
SHDN
2.5A (I ), 4MHz Synchronous Step-Down DC/DC Converter 95% Efficiency, V : 2.5V to 5.5V, V
: 0.8V, I : 60µA,
Q
OUT
IN
I
: <1µA, TSSOP16E Package
SHDN
LTC3440/
LTC3441
600mA/1.2A (I ), 2MHz/1MHz Synchronous Buck-Boost
95% Efficiency, V : 2.5V to 5.5V, V
: 2.5V, I : 25µA,
Q
OUT
IN
DC/DC Converter
I
: <1µA, 10-Lead MS Package
SHDN
LT3466
Full Function White LED Step-Up Converter with
Built-In Schottkys
Drives Up to 20 LEDs, Independent Step-Up Converters,
V : 2.7µV to 24V, DFN Package
IN
3465afa
LT/LT 0805 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2005
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