LT3958
High Input Voltage,
Boost, Flyback, SEPIC and
Inverting Converter
FEATURES
DESCRIPTION
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.
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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
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.
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Internal 7.2V Low Dropout Voltage Regulator
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Programmable Input Undervoltage Lockout with
Hysteresis
Programmable Soft-Start
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Thermally Enhanced QFN (5mm × 6mm) Package
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
APPLICATIONS
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Automotive
No R
and ThinSOT are trademarks of Linear Technology Corporation.
SENSE
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Telecom
All other trademarks are the property of their respective owners. Patents pending.
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Industrial
TYPICAL APPLICATION
High Efficiency Boost Converter
Efficiency vs Output Current
33μH
V
OUT
100
95
90
85
80
75
70
V
IN
V
= 24V
48V
IN
12V TO 40V
0.5A
4.7μF
s2
4.7μF
V
SW
392k
IN
EN/UVLO
GND
53.6k
LT3958
SGND
SYNC
SENSE1
464k
SENSE2
FBX
INTV
CC
RT SS
VC
10k
10nF
15.8k
41.2k
300kHz
0.33μF
4.7μF
0
400
500
100
200
300
OUTPUT CURRENT (mA)
3958 TA01b
3958 TA01a
3958f
1