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LT3481HDD#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24
LT3481
1
3481fc
36V, 2A, 2.8MHz Step-Down
Switching Regulator with
50µA Quiescent Current
The LT
®
3481 is an adjustable frequency (300kHz to 2.8MHz)
monolithic buck switching regulator that accepts input
voltages up to 34V (36V maximum). A high effi ciency
0.18Ω switch is included on the die along with a boost
Schottky diode and the necessary oscillator, control, and
logic circuitry. Current mode topology is used for fast
transient response and good loop stability. Low ripple
Burst Mode operation maintains high effi ciency at low
output currents while keeping output ripple below 15mV
in a typical application. In addition, the LT3481 can fur-
ther enhance low output current effi ciency by drawing
bias current from the output when V
OUT
is above 3V.
Shutdown reduces input supply current to less than 1μA
while a resistor and capacitor on the RUN/SS pin provide a
controlled output voltage ramp (soft-start). A power good
fl ag signals when V
OUT
reaches 90% of the programmed
output voltage. The LT3481 is available in 10-Pin MSOP
and 3mm x 3mm DFN packages with exposed pads for
low thermal resistance.
■
Automotive Battery Regulation
■
Power for Portable Products
■
Distributed Supply Regulation
■
Industrial Supplies
■
Wall Transformer Regulation
■
Wide Input Range: 3.6V to 34V Operating,
36V Maximum
■
2A Maximum Output Current
■
Low Ripple Burst Mode
®
Operation
50μA I
Q
at 12V
IN
to 3.3V
OUT
Output Ripple < 15mV
■
Adjustable Switching Frequency: 300kHz to 2.8MHz
■
Low Shutdown Current: I
Q
< 1μA
■
Integrated Boost Diode
■
Power Good Flag
■
Saturating Switch Design: 0.18Ω On-Resistance
■
1.265V Feedback Reference Voltage
■
Output Voltage: 1.265V to 20V
■
Soft-Start Capability
■
Synchronizable Between 275kHz to 475kHz
■
Small 10-Pin Thermally Enhanced MSOP and
(3mm x 3mm) DFN Packages
3.3V Step-Down Converter
SW
BIAS
FB
V
C
PG
RT
V
IN
BD
V
IN
4.5V TO
34V
V
OUT
3.3V
2A
4.7μF
0.47μF
330pF
22μF
200k
16.2k
60.4k
4.7μH
324k
GND
OFF ON
LT3481
3481 TA01
RUN/SS BOOST
Effi ciency
LOAD CURRENT (A)
0.0001
EFFICIENCY (%)
POWER LOSS (mW)
40
30
0.001 0.01 0.1 1 10
3481 TA01b
60
50
90
80
70
0.1
0.01
10.0
1.0
10000.0
1000.0
100.0
V
IN
= 12V
V
OUT
= 3.3V
L = 4.7μ
F = 800 kHz
TYPICAL APPLICATION
DESCRIPTION
FEATURES
APPLICATIONS
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
LT3481
2
3481fc
V
IN
, RUN/SS Voltage .................................................36V
BOOST Pin Voltage ...................................................56V
BOOST Pin Above SW Pin .........................................30V
FB, RT, V
C
Voltage .......................................................5V
BIAS, PG, BD Voltage ................................................30V
Maximum Junction Temperature........................... 125°C
LT3481E, LT3481I ............................................. 125°C
LT3481H ........................................................... 150°C
(Note 1)
Operating Temperature Range (Note 2)
LT3481E ............................................... –40°C to 85°C
LT3481I.............................................. –40°C to 125°C
LT3481H ............................................ –40°C to 150°C
Storage Temperature Range ................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
MSE Only .......................................................... 300°C
ABSOLUTE MAXIMUM RATINGS
TOP VIEW
DD PACKAGE
10-LEAD (3mm s 3mm) PLASTIC DFN
EXPOSED PAD (PIN 11) IS GND
MUST BE CONNECTED TO GND
10
9
6
7
8
4
5
3
11
2
1
RT
V
C
FB
BIAS
PG
BD
BOOST
SW
V
IN
RUN/SS
θ
JA
= 43°C/W
1
2
3
4
5
BD
BOOST
SW
V
IN
RUN/SS
10
9
8
7
6
RT
V
C
FB
BIAS
PG
TOP VIEW
MSE PACKAGE
10-LEAD PLASTIC MSOP
EXPOSED PAD (PIN 11) IS GND
MUST BE CONNECTED TO GND
11
θ
JA
= 40°C/W
PIN CONFIGURATION
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3481EDD#PBF LT3481EDD#TRPBF LBVS
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LT3481IDD#PBF LT3481IDD#TRPBF LBVV
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LT3481HDD#PBF LT3481HDD#TRPBF LBVS
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 150°C
LT3481EMSE#PBF LT3481EMSE#TRPBF LTBVT 10-Lead Plastic MSOP –40°C to 85°C
LT3481IMSE#PBF LT3481IMSE#TRPBF LTBVW 10-Lead Plastic MSOP –40°C to 125°C
LT3481HMSE#PBF LT3481HMSE#TRPBF LTBVT 10-Lead Plastic MSOP –40°C to 150°C
LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3481EDD LT3481EDD#TR LBVS
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LT3481IDD LT3481IDD#TR LBVV
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LT3481HDD LT3481HDD#TR LBVS
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 150°C
LT3481EMSE LT3481EMSE#TR LTBVT 10-Lead Plastic MSOP –40°C to 85°C
LT3481IMSE LT3481IMSE#TR LTBVW 10-Lead Plastic MSOP –40°C to 125°C
LT3481HMSE LT3481HMSE#TR LTBVT 10-Lead Plastic MSOP –40°C to 150°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 part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to:
http://www.linear.com/tapeandreel/
LT3481
3
3481fc
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Input Voltage
●
3 3.6 V
Quiescent Current from V
IN
V
RUN/SS
= 0.2V 0.01 0.5 μA
V
BIAS
= 3V, Not Switching
●
22 60 μA
V
BIAS
= 0, Not Switching 75 120 μA
Quiescent Current from BIAS V
RUN/SS
= 0.2V 0.01 0.5 μA
V
BIAS
= 3V, Not Switching
●
50 120 μA
V
BIAS
= 0, Not Switching 05 μA
Minimum Bias Voltage 2.7 3 V
Feedback Voltage
●
1.25
1.24
1.265
1.265
1.29
1.3
V
V
FB Pin Bias Current (Note 3) V
FB
= 1.25V, V
C
= 0.4V
●
30 100 nA
FB Voltage Line Regulation 4V < V
IN
< 34V 0.002 0.02 %/V
Error Amp g
m
330 μMho
Error Amp Gain 800
V
C
Source Current 65 μA
V
C
Sink Current 85 μA
V
C
Pin to Switch Current Gain 3.5 A/V
V
C
Clamp Voltage 2V
Switching Frequency R
T
= 8.66k
R
T
= 29.4k
R
T
= 187k
2.5
1.25
250
2.8
1.4
300
3.1
1.55
350
MHz
MHz
kHz
Minimum Switch Off-Time
●
130 200 nS
Switch Current Limit Duty Cycle = 5% 3.2 3.8 4.4 A
Switch V
CESAT
I
SW
= 2A 360 mV
Boost Schottky Reverse Leakage V
SW
= 10V, V
BIAS
= 0V 0.02 2 μA
Minimum Boost Voltage (Note 4)
●
1.5 2.1 V
BOOST Pin Current I
SW
= 1A 18 35 mA
RUN/SS Pin Current V
RUN/SS
= 2.5V 5 10 μA
RUN/SS Input Voltage High 2.5 V
RUN/SS Input Voltage Low 0.2 V
PG Threshold Offset from Feedback Voltage V
FB
Rising 122 mV
PG Hysteresis 5 mV
PG Leakage V
PG
= 5V 0.1 1 μA
PG Sink Current V
PG
= 3V
●
100 600 μA
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
reliability and lifetime.
Note 2: The LT3481E is guaranteed to meet performance specifi cations
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 statistical process controls. The LT3481I specifi cations are
guaranteed over the –40°C to 125°C temperature range. The LT3481H
specifi cations are guaranteed over the –40°C to 150°C operating
temperature range. High junction temperatures degrade operating
lifetimes. Operating lifetime is derated at junction temperatures greater
than 125°C.
Note 3: Bias current fl ows into the FB pin.
Note 4: This is the minimum voltage across the boost capacitor needed
to guarantee full saturation of the switch.
The ● denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 10V, V
RUNS/SS
= 10V V
BOOST
= 15V, V
BIAS
= 3.3V unless otherwise
noted. (Note 2)
ELECTRICAL CHARACTERISTICS
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LT3481HDD#PBF

Mfr. #:
Buy LT3481HDD#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 36V, 2A (Iout), 2.8MHz Step-Down Switching Regulator in 3mm x 3mm DFN
Lifecycle:
New from this manufacturer.
Delivery:
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