LT3482
1
3482fa
90V Boost DC/DC
Converter with APD
Current Monitor
The LT®3482 is a fi xed frequency current mode step-up
DC/DC converter with voltage doubler designed to bias
avalanche photodiodes (APDs) in optical receivers. It can
provide up to 90V output. The LT3482 features high side
APD current monitoring with better than 10% relative ac-
curacy over the entire temperature range. The integrated
power switch, Schottky diodes and APD current monitor
allow a small converter footprint and low solution cost.
Constant switching frequency results in predictable output
noise that is easy to fi lter. The inductor-based topology
ensures an input free from switching noise. An integrated
high side current monitor produces a current proportional
to APD current with better than 10% relative accuracy
over four decades of dynamic range in the input range of
250nA to 2.5mA. This current can be used as a reference
to provide a digitally programmed output voltage via the
CTRL pin. The LT3482 is available in the tiny footprint
(3mm × 3mm) 16-lead QFN package.
■ APD Bias
■ PIN Diode Bias
■ Optical Receivers and Modules
■ Fiber Optic Network Equipment
■ High Output Voltage: Up to 90V
■ Integrated Schottky Diodes
■ 48V, 280mA Internal Switch
■ High Side APD Current Monitor
■ Adjustable Switching Frequency: 650kHz or 1.1MHz
■ Wide VIN Range: 2.5V to 16V
■ Surface Mount Components
■ Low Shutdown Current: <1µA
■ Soft-Start
■ Internal Compensation
■ CTRL Pin Allows Output Adjustment with No Polarity
Inversion
■ 3mm × 3mm 16-Lead QFN Package
APPLICATIO S
U
FEATURES DESCRIPTIO
U
TYPICAL APPLICATIO
U
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
1µF
0.1µF
1M
MONINVIN
fSET
SHDN
CTRL
GND
VOUT2
VOUT1
FB
SW PUMP
LT3482
MON APD
OFF ON
VIN
5V
14k
85V
AT 2.5mA
3482 TA01a
0.47µF
0.47µF
0.1µF
10k
10nF
0.1µF
10µH
VAPD
RIPPLE
100
m
V/DIV
500ns/DIV 3482 TA01b
Output Voltage Ripple
LT3482
2
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Input Voltage (VIN) ....................................................16V
VOUT1, SW Voltage ....................................................48V
VOUT2, PUMP, MONIN, APD Voltage ..........................90V
FB Voltage ...................................................................5V
SHDN, fSET, CTRL Voltage .........................................16V
MON Voltage .............................................................12V
Operating Temperature Range
(Note 2) .................................................... –40°C to 85°C
Maximum Junction Temperature .......................... 125°C
Storage Temperature Range ................... –65°C to 125°C
(Note 1)
The
● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C. VIN = 3V, V
⎯
S
⎯
H
⎯
D
⎯
N = 3V unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Operating Voltage 2.5 V
Maximum Operating Voltage 16 V
Feedback Voltage CTRL = 1.5V
●
1.215
1.200
1.235 1.255
1.260
V
V
Feedback Line Regulation 0.025 0.07 %/V
FB Pin Bias Current ●30 100 nA
Supply Current FB = 1.3V, Not Switching
V
⎯
S
⎯
H
⎯
D
⎯
N = 0
3.3
0.1
4.0
0.5
mA
µA
Switching Frequency fSET = 0V
fSET = 2V
580
1.0
650
1.1
750
1.3
kHz
MHz
Maximum Duty Cycle fSET = 0V 95 %
Switch Current Limit 280 360 420 mA
Switch VCESAT ISW = 150mA 130 220 mV
Switch Leakage Current SW = 5V 2 µA
Schottky Forward Voltage ISCHOTTKY = 150mA 880 mV
Schottky Reverse Leakage VOUT1 – SW = 50V 5 µA
SHDN Voltage High 1.5 V
ELECTRICAL CHARACTERISTICS
ABSOLUTE AXI U RATI GS
WWWU
16 15 14 13
5 6 7 8
TOP VIEW
17
UD PACKAGE
16-LEAD (3mm × 3mm) PLASTIC QFN
9
10
11
12
4
3
2
1NC
APD
MONIN
VOUT2
SHDN
VIN
GND
GND
MON
fSET
FB
CTRL
VOUT1
PUMP
SW
SW
TJMAX = 125°C, θJA = 68°C/W, θJC = 4.2°C/W
EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB
PIN CONFIGURATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3482EUD#PBF
LT3482IUD#PBF
LT3482EUD#TRPBF
LT3482IUD#TRPBF
LCFG
LCFG
16-Lead (3mm × 3mm) Plastic QFN
16-Lead (3mm × 3mm) Plastic QFN
0°C to 85°C
–40°C to 125°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.
For more information on lead free parts, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to: http://www.linear.com/tapeandreel/
ORDER INFORMATION
LT3482
3
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Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device reli-
ability and lifetime.
PARAMETER CONDITIONS MIN TYP MAX UNITS
SHDN Voltage Low 0.4 V
SHDN Pin Bias Current 35 50 µA
fSET Voltage High 1.5 V
fSET Voltage Low 0.4 V
fSET Bias Current fSET = 2V 22 40 µA
CTRL to FB Offset CTRL = 0.5V
●
–5
–10
2
2
10
15
mV
mV
APD Current Monitor Gain IAPD = 250nA, 10V ≤ MONIN ≤ 90V
IAPD = 2.5mA, 20V ≤ MONIN ≤ 90V
●
●
0.180
0.185
0.20
0.20
0.215
0.215
Monitor Output Voltage Clamp 11.5 V
APD Monitor Voltage Drop MONIN – APD at IAPD = 1mA, MONIN = 90V 5 V
MONIN Pin Current Limit APD = 0V, MONIN = 40V 15 mA
The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C. VIN = 3V, V
⎯
S
⎯
H
⎯
D
⎯
N = 3V unless otherwise noted.
ELECTRICAL CHARACTERISTICS
Note 2: The LT3482E is guaranteed to meet specifi ed performance from
0°C to 85°C. Specifi cations over the –40°C to 85°C operating temperature
range are assured by design, characterization and correlation with statisti-
cal process controls. The LT3482I is guaranteed to meet performance
specifi cations over the –40°C to 125°C operating temperature range.
LT3482
4
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Oscillator Frequency vs
Temperature
Switch Current Limit
vs Duty Cycle
Switch Current Limit vs
Temperature
Current Monitor Output vs MONIN APD Current Monitor Accuracy
APD Current Monitor Accuracy
vs Temperature
TYPICAL PERFOR A CE CHARACTERISTICS
UW
TEMPERATURE (°C)
–50
900
1000
1200
25 75
3482 G01
800
700
–25 0 50 100 125
600
500
1100
FREQUENCY (kHz)
fSET = 2V
fSET = 0V
DUTY CYCLE (%)
0
SWITCH CURRENT LIMIT (mA)
150
200
250
60 100
3482 G02
100
50
020 40 80
300
350
400
TEMPERATURE (°C)
–50
SWITCH CURRENT LIMIT (mA)
340
25
3482 G03
280
240
–25 0 50
220
200
360
320
300
260
75 100 125
MONIN (V)
10
18
IMON (µA)
19
20
21
22
20 30 40 50
3482 G04
60 70 80 90
IAPD = 100µA
IAPD (A)
1.0E-08 1.0E-06 1.0E-04 1.0E-02
1.0E-02
1.0E-03
1.0E-04
1.0E-05
1.0E-06
1.0E-07
1.0E-08
1.0E-09
3482 G05
IMON (A)
MONIN = 90V
TEMPERATURE (°C)
–50
ERROR (%)
–2
0
2
25 75
3482 G06
–4
–6
–25 0 50 100 125
–8
–10
IAPD = 2.5mA
IAPD = 10µA
IAPD = 250nA
MONIN = 90V
Current Monitor Voltage Drop
vs Reference Current
REFERENCE CURRENT (A)
1.00E-07 1.00E-05 1.00E-03
5
6
7
!"& /%
4
3
2
1
0
MONIN – APD (V)
Switch Saturation Voltage (VCESAT)
SWITCH CURRENT (mA)
0
VCESAT (mV)
200
250
300
150 250
3482 G08
150
100
50 100 200 300 350
50
0
FB Pin Voltage vs Temperature
TEMPERATURE (°C)
–50
FB PIN VOLTAGE (V)
1.24
1.25
25 75
3482 G09
1.23
–25 0 50 100 125
1.22
VIN = 16V
VIN = 3V
(TA = 25°C unless otherwise specifi ed)
LT3482
5
3482fa
UU
U
PI FU CTIO S
APD (Pin 2): Connect APD cathode to this pin.
MONIN (Pin 3): Current Monitor Power Supply Pin. An
external lowpass fi lter can be included here to further
reduce supply voltage ripple.
VOUT2 (Pin 4): Voltage Doubler Output Pin. Put a 50V
rated capacitor between this pin and VOUT1. Tie a resistor
divider to the FB pin and GND.
VOUT1 (Pin 5): Boost Output Pin. Put a capacitor between
this pin and the GND plane. Minimize the length of the
trace to the capacitor.
PUMP (Pin 6): Charge Pump Pin. Put a 50V rating bypass
capacitor between SW and PUMP to form a complete volt-
age doubler with the internal integrated Schottky diodes.
Minimize trace length to the capacitor.
SW (Pins 7, 8): Switch Pin. Minimize the trace length on
this pin to reduce EMI.
GND (Pins 9, 10): Ground. Pins connected internally. For
best performance, connect both pins to board ground.
VIN (Pin 11): Input Supply Pin. This pin must be locally
bypassed.
SHDN (Pin 12): Shutdown Pin. Tie to 1.5V or higher to
enable device; 0.4V or less to disable device. This pin also
functions as soft-start between 1.5V and 2V.
CTRL (Pin 13): Internal Reference Override Pin. This allows
the FB voltage to be externally set between 0V and 1.2V.
Tie this pin higher than 1.5V to use the internal reference
of 1.235V.
FB (Pin 14): Feedback Pin. Connect the output resistor
divider tap here.
fSET (Pin 15): Oscillator Frequency Selection Pin. Tie this
pin to above 1.5V or higher to select the higher switching
frequency of 1.1MHz. For lower switching frequency, tie
to GND.
MON (Pin 16): Current Monitor Output Pin. It sources a
current equal to 20% of the APD current and converts to
a reference voltage through an external resistor.
Exposed Pad (Pin 17): GND. This pin must be soldered
to the PCB.
LT3482
6
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Σ
–
+
+
–
+
RC
EAMP
A1
A2
PWM
COMPARATOR
CURRENT
SENSE
AMPLIFIER
DRIVER
CC
CS
RQ1
Q
S
–
+
RAMP
GENERATOR
APD
CURRENT
MIRROR
1.235V
REFERENCE
650kHz/1.1MHz
OSCILLATOR
CONTROL
BLOCK
11
VIN
VIN
10 GND
12 SHDN
RS
VIN
9GND
4
VOUT2
3
MONIN
2
APD
1
NC
3482 BD
13 CTRL 14 FB 16 MON
6
PUMP
D3
D2
D1
8
SW
CFLY
C2
C3
R1
FB
R2
C1
L1
5
VOUT1
R3
15
fSET
CPL
C4
7
SW
FU CTIO AL DIAGRA
UU
W
OPERATIO
U
The LT3842 boost converter uses a constant frequency
current mode control scheme to provide excellent line
and load regulation. Operation can be best understood by
referring to the Functional Diagram. 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 amplifi er A1, and is simply an amplifi ed version of the
difference between the feedback voltage and the reference
voltage of 1.235V, or externally provided CTRL voltage.
In this manner, the error amplifi er sets the correct peak
current level to keep the output in regulation. If the error
amplifi er’s output increases, more current is delivered to
the output; if it decreases, less current is delivered.
The LT3482 has an integrated high side APD current moni-
tor with a 5:1 ratio. The MONIN pin can accept a supply
voltage up to 90V, which is suitable for APD photodiode
applications. The MON pin has an open-circuit protection
feature and is internally clamped to 11.5V.
If an APD is tied to the APD pin, the current will be mir-
rored to the MON pin and converted to a voltage signal
by the resistor R3. This voltage signal can be used to
drive an external control block to adjust the APD voltage
by adjusting the feedback threshold of EAMP A1 through
the CTRL input.
LT3482
7
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APPLICATIO S I FOR ATIO
WUUU
Switching Frequency
The LT3482 can operate at either 650kHz nominal or
1.1MHz nominal; the voltage at the fSET pin selects which
frequency is used. At 1.1MHz, a physically smaller induc-
tor and capacitor can be used in a given application, but
higher frequencies will slightly decrease effi ciency and
maximum duty cycle. Generally if effi ciency and maximum
duty cycle are crucial, the lower switching frequency should
be selected by connecting fSET to GND. If application size
and cost are more important, connect fSET to VIN to select
the higher switching frequency.
Inrush Current
The LT3482 has built-in Schottky diodes for the boost
and charge pump. When supply voltage is applied to the
VIN pin, the voltage difference between VIN and VOUT1
generates inrush current fl owing from input through the
inductor and the Schottky diode (D1 in the Functional
Diagram) to charge the output capacitor. The selection of
inductor and capacitor value should ensure the peak of
the inrush current to be below 1A. In addition, the LT3482
turn-on should be delayed until the inrush current is less
than the maximum current limit. The peak inrush current
can be estimated as follows:
IV
L
C
L
C
PIN
=
⎛
⎝
⎜
⎜
⎜
⎜
⎞
⎠
⎟
⎟
⎟
⎟
–.
–
• exp –
–
06
121
π
where L is the inductance and C is the output capacitance.
Table 1 gives inrush peak currents for some component
selections.
Table 1. Inrush Peak Current
VIN (V) L (µH) C (µF) IP (A)
5 10 1 0.87
5 22 1 0.68
Setting Output Voltage
The LT3482 is equipped with both an internal 1.235V refer-
ence and an auxiliary reference input (the CTRL pin). This
allows users to select between using the built-in reference
and supplying an external reference voltage. The voltage
at the CTRL pin can be adjusted while the chip is operating
to alter the output voltage of LT3482 for purposes such as
APD’s bias voltage adjustment. To use the internal 1.235V
reference, the CTRL pin should be held higher than 1.5V,
which can be done by tying it to V
IN
. When the CTRL
pin is between 0V and 1.2V, the LT3482 will regulate the
output such that the FB pin voltage is equal to the CTRL
pin voltage.
To set the output voltage, select the values of R1 and R2
(see Figure 1) according to the following equation:
RRV
V
OUT
REF
12 1
2
=⎛
⎝
⎜⎞
⎠
⎟
–
where V
REF
= 1.235V if the internal reference is used or
VREF = CTRL if CTRL is between 0V and 1.2V. R2 can be
selected to load the output to maintain a constant switching
frequency when the APD load is very low. Preventing entry
into pulse skipping mode is an important consideration
for post fi ltering the regulator output.
VOUT2
CTRL
R1
4
1413
3482 F01
FB
LT3482
R2
Figure 1. Output Voltage Feedback Connection
LT3482
8
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Inductor Selection
The inductors used with the LT3482 should have a satura-
tion current rating of 0.3A or greater. If the device is used in
an application where the input supply will be hot-plugged,
the saturation current rating should be equal to or greater
than the peak inrush current. For best loop stability, the
inductor value selected should provide a ripple current of
60mA or more. For a given VIN and VOUT1, the inductor
value to use in continuous conduction mode (CCM) is
estimated by the formula:
LDV
mA
IN
=•
•ƒ60
where:
DVV
V
OUT IN
OUT
=+
+
1
1
1
1
–
and f is the switching frequency.
To achieve low output voltage ripple, a small value in-
ductor should be selected to force the LT3482 work in
discontinuous conduction mode (DCM). The inequality
is true when the LT3482 is operating in discontinuous
condition mode.
LDV
I
IN
LIMIT
<•
•ƒ
where ILIMIT is the switch current limit. Operating in DCM
reduces the maximum load current and the conversion
effi ciency.
Capacitor Selection
Low ESR capacitors should be used at the output to
minimize the output voltage ripple. Use only X5R and
X7R types because they retain their capacitance over
wider voltage and temperature ranges than other types.
High output voltages typically require less capacitance for
loop stability. For applications with out voltage less than
45V, intermediate output pin VOUT1 can directly serve as
the output pin. Typically use a 2µF capacitor for output
voltage less than 25V and 1µF capacitor for output voltage
between 25V and 45V. When output voltage goes beyond
45V, a charge pump must be formed with cascaded 0.47µF
capacitors C1 and C2 at the output nodes. A typical 0.1µF
capacitor is used as the fl ying capacitor CFLY to form the
charge pump. Always use a capacitor with suffi cient volt-
age rating.
Either ceramic or solid tantalum capacitors may be used
for the input decoupling capacitor, which should be placed
as close as possible to the LT3482. A 1µF capacitor is
suffi cient for most applications.
Phase Lead Capacitor
A small value capacitor (i.e., 10pF to 22pF) can be added
in parallel with the resistor between the output and the FB
pin to reduce output perturbation due to a load step and
to improve transient response. This phase lead capacitor
introduces a pole-zero pair to the feedback that boosts
phase margin near the crossover frequency.
The APD is very sensitive to a noisy bias supply. To
lowpass fi lter noise from the internal reference and error
amplifi er, a 0.1µF phase lead capacitor can be used. The
corner frequency of the noise fi lter is R1 • CPL.
APD Current Monitor
The power supply switching noise associated with a switch-
ing power supply can interfere with the photodiode DC
measurement. To suppress this noise, a 0.1µF capacitor
is recommended at APD pin. An additional output lowpass
fi lter, a 10k resistor and a 10nF capacitor in parallel at
MON pin, can further reduce the power supply noise and
other wide band noise, which might limit the measurement
accuracy of low level signals. For applications requiring
fast current monitor response time, a RC lowpass fi lter at
MONIN pin is used to replace the 0.1µF capacitor at APD
pin, as illustrated in Figure 2.
APPLICATIO S I FOR ATIO
WUUU
MONIN
RMON
CMON
3482 F02
VOUT2
LT3482
VOUT1
APD
C2
C1
Figure 2
LT3482
9
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Figure 3. Suggested Layout
APPLICATIO S I FOR ATIO
WUUU
In some applications, a long cable or wire is used to connect
the LT3482 to APD. When APD is shorted to GND, APD pin
voltage might ring below ground and damage the internal
circuitry. To prevent damage during short-circuit event, a
20Ω resistor must be added in series with the APD.
Layout Hints
The high speed operation of the LT3842 demands care-
ful attention to board layout. You will not get advertised
performance with careless layout. Figure 3 shows the
recommended component placement.
16 15 14 13
5 6 7
17
8
9
10
11
12
4
3
2
1
C2 CFLY
CPL
CMON
(OPT)
R1
APD
R2
C1
3482 F03
L1
RMON
(OPT)
CIN
GND
VIN
CTRL
MON fSET
LT3482
10
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C1
1µF
C2
0.1µF
R1
100Ω
APD Input Load for Current Monitor
Step Response Measurement
R4
10k
MONINVIN
fSET
SHDN
CTRL
GND
VOUT2
VOUT1
FB
SW PUMP
LT3482
MON APD
OFF ON
VIN
3.3V
R3
16.5k
R2
1M
70V
AT 2mA
3482 TA03a
C4
0.47µF
C5
0.47µF
C1: MURATA X7R GRM21BR71C105KA01B
C2: AVX 06035C104KAT2A
C3, C6: AVX 08051C104KAT2A
C4, C5: MURATA X7R GRM31MR71H474KA01B
L1: COILCRAFT ME3220-682ML OR EQUIVALENT
C6
0.1µF
C3
0.1µF
L1
6.8µH
2APD
10k
0V
5V
NODE A
2k
0mA
2mA
TYPICAL APPLICATIO S
U
C1
1µF
C2
0.1µF
R1
1M
MONINVIN
fSET
SHDN
CTRL
GND
VOUT2
VOUT1
FB
SW PUMP
LT3482
MON APD
OFF ON
VIN
5V
R2
14k
85V
AT 2.5mA
3482 TA02a
C4
0.47µF
C5
0.47µF
C3
0.1µF
C1: MURATA X7R GRM21BR71C105KA01B
C2: AVX 06035C104KAT2A
C3, C6: AVX 08051C104KAT2A
C4, C5: MURATA X7R GRM31MR71H474KA01B
C7: MURATA GRM2167U1H103JA01B
L1: COILCRAFT ME3220-103KL OR EQUIVALENT
R3
10k
C7
10nF
C6
0.1µF
L1
10µH
5V to 85V APD Bias Power Supply Effi ciency
IMONIN (mA)
0
EFFICIENCY (%)
40
50
60
1.5 2.5
3482 TA02b
30
20
0.5 1 2 3 3.5
10
0
3.3V to 70V APD Bias Power Supply with Fast Current Monitor Response Effi ciency
IMONIN (mA)
0
0
EFFICIENCY (%)
10
20
30
40
50
60
0.5 1 1.5 2
3482 TA03b
2.5
VMON
2V/DIV
VNODE A
20V/DIV
REF GND
REF GND
500ns/DIV 3482 TA03c
Current Monitor Step Response
LT3482
11
3482fa
U
PACKAGE DESCRIPTIO
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
UD Package
16-Lead Plastic QFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1691)
3.00 ± 0.10
(4 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
1.45 ± 0.05
(4 SIDES)
NOTE:
1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WEED-2)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON THE TOP AND BOTTOM OF PACKAGE
PIN 1
TOP MARK
(NOTE 6)
0.40 ± 0.10
BOTTOM VIEW—EXPOSED PAD
1.45 ± 0.10
(4-SIDES)
0.75 ± 0.05 R = 0.115
TYP
0.25 ± 0.05
1
PIN 1 NOTCH R = 0.20 TYP
OR 0.25 × 45° CHAMFER
15 16
2
0.50 BSC
0.200 REF
2.10 ± 0.05
3.50 ± 0.05
0.70 ±0.05
0.00 – 0.05
(UD16) QFN 0904
0.25 ±0.05
0.50 BSC
PACKAGE OUTLINE
LT3482
12
3482fa
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2006
LT 0207 REV A • PRINTED IN USA
PART NUMBER DESCRIPTION COMMENTS
LT1930/LT1930A 1A (ISW), 1.2MHz/2.2MHz High Effi ciency Step-Up
DC/DC Converters
VIN: 2.6V to 16V, VOUT(MAX) = 34V, IQ = 4.2mA/5.5mA, ISD < 1µA,
ThinSOTTM Package
LT3460 0.3A (ISW), 1.3MHz High Effi ciency Step-Up
DC/DC Converter
VIN: 2.5V to 16V, VOUT(MAX) = 38V, IQ = 2mA, ISD < 1µA, ThinSOT
Package
LT3461/LT3461A 0.3A (ISW), 1.3MHz/3MHz High Effi ciency Step-Up
DC/DC Converters with Integrated Schottky
VIN: 2.5V to 16V, VOUT(MAX) = 38V, IQ = 2.8mA, ISD < 1µA, SC70 and
ThinSOT Package
LT3465/LT3465A Constant Current, 1.2MHz/2.7MHz High Effi ciency White
LED Boost Regulator with Integrated Schottky
VIN: 2.7V to 16V, VOUT(MAX) = 34V, IQ = 1.9mA, ISD < 1µA, ThinSOT
Package
ThinSOT is a trademark on Linear Technology Corporation.
RELATED PARTS
U
TYPICAL APPLICATIO
C1
1
m
F
R3
100
W
R4
10k
MONINVIN
fSET
SHDN
CTRL
GND
VOUT2
VOUT1
FB
SW PUMP
LT3482
MON APD
OFF ON
VIN
3.3V
R2
28k
R1
1M
40V
AT 3mA
3482 TA04a
C2
1
m
F
C1: MURATA X7R GRM21BR71C105KA01B
C2: MURATA X7R GRM31MR71H105KA88B
C3, C4: AVX 06035C104KAT2A
L1: COILCRAFT ME3220-562ML OR EQUIVALENT
C3
0.1
m
F
C4
0.1
m
F
L1
5.6
m
H
IMONIN (mA)
0
EFFICIENCY (%)
40
50
60
3
3482 TA04b
30
20
12
0.5 3.5
1.5 2.5 4
10
0
70
3.3V to 40V APD Bias Power Supply Effi ciency
