LT3758A_15 Datasheet, PDF (1/36 Pages) Linear Technology – High Input Voltage, Boost, Flyback, SEPIC and Inverting Controller

Features
n _{Wide Input Voltage Range: 5.5V to 100V}
n _{Positive or Negative Output Voltage Programming}
with a Single Feedback Pin
n _{Current Mode Control Provides Excellent Transient}
Response
n _{Programmable Operating Frequency (100kHz to}
1MHz) with One External Resistor
n _{Synchronizable 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 _{Small 10-Lead DFN (3mm × 3mm) and}
MSOPE Packages
Applications
n _Automotive
n _Telecom
n _Industrial
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and No R_SENSE and ThinSOT are trademarks of Linear Technology Corporation. All other
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LT3758/LT3758A
High Input Voltage,
Boost, Flyback, SEPIC and
Inverting Controller
Description
The LT^®3758/LT3758A are wide input range, current
mode, DC/DC controllers which are capable of generating
either positive or negative output voltages. They can be
configured as either a boost, flyback, SEPIC or inverting
converter. The LT3758/LT3758A drive a low side external
N-channel power MOSFET 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 LT3758/LT3758A 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 5.5V,
and a low shutdown quiescent current of less than 1µA,
make the LT3758/LT3758A ideally suited for battery-
powered systems.
The LT3758/LT3758A feature soft-start and frequency
foldback functions to limit inductor current during start-up
and output short-circuit. The LT3758A has improved load
transient performance compared to the LT3758.
Typical Application
12V Output Nonisolated Flyback Power Supply
V_IN
36V TO
72V
D1
C_IN
2.2µF
100V
X7R
63.4k
200kHz
1M
44.2k
0.47µF
V_IN
SHDN/UVLO
0.022µF
100V
6.2k
T1
1,2,3
(SERIES)
D_SN
4,5,6
(PARALLEL)
LT3758
SYNC
GATE
SW
105k
M1
1%
RT
SS
V_C
SENSE
FBX
GND INTV_CC
1N4148 5.1Ω
100pF
10k
10nF
C_VCC
4.7µF
10V
X5R
0.030Ω
15.8k
1%
V_OUT
12V
1.2A
C_OUT
47µF
X5R
3758 TA01
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