LT3958
High Input Voltage,
Boost, Flyback, SEPIC and
Inverting Converter
Description
Features
Wide Input Voltage Range: 5V to 80V
n Single Feedback Pin for Positive or Negative
Output Voltage
n Internal 3.3A/84V Power Switch
n Current Mode Control Provides Excellent Transient
Response
n Programmable Operating Frequency (100kHz to
1MHz) with One External Resistor
n Synchronizeable to an External Clock
n Low Shutdown Current < 1µA
n Internal 7.2V Low Dropout Voltage Regulator
n Programmable Input Undervoltage Lockout with
Hysteresis
n Programmable Soft-Start
n Thermally Enhanced QFN (5mm × 6mm) Package
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.
Applications
The LT3958 features soft-start and frequency foldback
functions to limit inductor current during start-up.
n
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.
Automotive
Telecom
n Industrial
n
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
No RSENSE and ThinSOT are trademarks of Analog Devices, Inc. All other trademarks are the
property of their respective owners. Patents pending.
n
Typical Application
High Efficiency Boost Converter
Efficiency vs Output Current
VIN
12V TO 40V
4.7µF
VIN
392k
4.7µF
×2
SW
GND
EN/UVLO
53.6k
LT3958
SGND
SENSE1
SYNC
SENSE2
464k
VOUT
48V
0.5A
100
VIN = 24V
95
EFFICIENCY (%)
33µH
90
85
80
FBX
RT
41.2k
300kHz
INTVCC
VC
SS
0.33µF
10k
15.8k
4.7µF
75
70
0
10nF
400
100
200
300
OUTPUT CURRENT (mA)
500
3958 TA01b
3958 TA01a
3958fa
For more information www.linear.com/LT3958
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