Datasheet

LT3958
1
3958fa
For more information www.linear.com/LT3958
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Wide Input Voltage Range: 5V to 80V
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Single Feedback Pin for Positive or Negative
Output Voltage
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Internal 3.3A/84V Power Switch
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Current Mode Control Provides Excellent Transient
Response
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Programmable Operating Frequency (100kHz to
1MHz) with One External Resistor
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Synchronizeable to an External Clock
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Low Shutdown Current < 1µA
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Internal 7.2V Low Dropout Voltage Regulator
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Programmable Input Undervoltage Lockout with
Hysteresis
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Programmable Soft-Start
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Thermally Enhanced QFN (5mm × 6mm) Package
Typical applicaTion
DescripTion
High Input Voltage,
Boost, Flyback, SEPIC and
Inverting Converter
The LT
®
3958 is a wide input range, current mode, DC/DC
converter which is capable of generating either positive
or negative output voltages. It can be configured as either
a boost, flyback, SEPIC or inverting converter. It features
an internal low side N-channel power MOSFET rated for
84V at 3.3A and driven from an internal regulated 7.2V
supply. The fixed frequency, current-mode architecture
results in stable operation over a wide range of supply
and output voltages.
The operating frequency of LT3958 can be set with an
external resistor over a 100kHz to 1MHz range, and can
be synchronized to an external clock using the SYNC pin.
A minimum operating supply voltage of 5V, and a low
shutdown quiescent current of less than 1µA, make the
LT3958 ideally suited for battery-powered systems.
The LT3958 features soft-start and frequency foldback
functions to limit inductor current during start-up.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
No R
SENSE
and ThinSOT are trademarks of Analog Devices, Inc. All other trademarks are the
property of their respective owners. Patents pending.
High Efficiency Boost Converter
FeaTures
applicaTions
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Automotive
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Telecom
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Industrial
Efficiency vs Output Current
SENSE2
SENSE1
LT3958
33µH
V
IN
SW
GND
FBX
RT SS
INTV
CC
EN/UVLO
SYNC
SGND
53.6k
VC
3958 TA01a
392k
41.2k
300kHz
4.7µF
0.33µF
10k
10nF
464k
15.8k
4.7µF
×2
V
OUT
48V
0.5A
V
IN
12V TO 40V
4.7µF
OUTPUT CURRENT (mA)
0
70
EFFICIENCY (%)
75
80
85
90
95
100
100 200 300
400
3958 TA01b
500
V
IN
= 24V
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