LT3434
High Voltage 3A, 200kHz
Step-Down Switching Regulator
with 100µA Quiescent Current
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DESCRIPTIO
FEATURES
The LT®3434 is a 200kHz monolithic buck switching
regulator that accepts input voltages up to 60V. A high
efficiency3A,0.1Ωswitchisincludedonthediealongwith
all the necessary oscillator, control and logic circuitry.
Current mode topology is used for fast transient response
and good loop stability.
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Wide Input Range: 3.3V to 60V
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3A Peak Switch Current
Burst Mode® Operation: 100µA Quiescent Current**
Low Shutdown Current: IQ < 1µA
Power Good Flag with Programmable Threshold
Load Dump Protection to 60V
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200kHz Switching Frequency
Innovative design techniques integrated in a new high
voltage process achieve high efficiency over a wide input
range. Efficiency is maintained over a wide output current
rangebyemployingBurstModeoperationatlowcurrents,
utilizing the output to bias the internal circuitry, and by
using a supply boost capacitor to fully saturate the power
switch. Patented circuitry maintains peak switch current
over the full duty cycle range.* Shutdown reduces input
supply current to less than 1µA. External synchronization
canbeimplementedbydrivingtheSYNCpinwithlogic-level
inputs. A single capacitor from the CSS pin to the output
providesacontrolledoutputvoltageramp(soft-start).The
device also has a power good flag with a programmable
thresholdandtime-out,andthermalshutdownprotection.
Saturating Switch Design: 0.1Ω
Peak Switch Current Maintained Over
Full Duty Cycle Range*
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1.25V Feedback Reference Voltage
Easily Synchronizable
Soft-Start Capability
Small 16-Pin Thermally Enhanced TSSOP Package
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APPLICATIO S
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High Voltage Power Conversion
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14V and 42V Automotive Systems
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Industrial Power Systems
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Distributed Power Systems
The LT3434 is available in a 16-pin TSSOP package with
exposed pad leadframe for low thermal resistance.
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Battery-Powered Systems
, LTC and LT are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Burst Mode is a registered
trademark of Linear Technology Corporation. *Protected by U.S. Patents including
6498466. **See Burst Mode Operation section for conditions.
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TYPICAL APPLICATIO
Efficiency and Power Loss
vs Load Current
Supply Current vs
Input Voltage
14V to 3.3V Step-Down Converter with
150
125
100
75
100
75
50
25
0
10
100µA No Load Quiescent Current
V
= 12V
V
= 3.3V
IN
L = 33µH
= 100µF
OUT
V
OUT
= 5V
V
3.3V
2A
C
OUT
OUT
V
IN
V
BOOST
SW
IN
1
4.7µF
100V
CER
33µH
0.68µF
4148
EFFICIENCY
= 3.3V
SHDN
0.1µF
LT3434
V
OUT
30MQ100
C
SS
0.1
0.01
0.001
V
C
C
470pF
V
BIAS
4700pF
10k
TYPICAL POWER
LOSS
165k
1%
50
27pF
FB
100µF
6.3V
TANT
T
PGFB
PG
1µF
SYNC
GND
25
100k
1%
0
3434 TA01
0
10
30
40
50
60
0.0001 0.001
0.1
0.01
LOAD CURRENT (A)
1
10
20
INPUT VOLTAGE (V)
3434 TA02a
3434 TA02b
3434f
1