LT3757A_15 Datasheet, PDF (1/36 Pages) Linear Technology – Boost, Flyback, SEPIC and Inverting Controller

LT3757/LT3757A
Boost, Flyback, SEPIC and
Inverting Controller
Features
n _{Wide Input Voltage Range: 2.9V to 40V}
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 Thermally}
Enhanced 10-Pin MSOP Packages
Applications
n _{Automotive and Industrial Boost, Flyback, SEPIC and}
Inverting Converters
n _{Telecom Power Supplies}
n _{Portable Electronic Equipment}
Description
The LT^®3757/LT3757A 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 LT3757/LT3757A 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 LT3757/LT3757A 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 low minimum operating supply voltage of
2.9V, and a low shutdown quiescent current of less than
1µA, make the LT3757/LT3757A ideally suited for battery-
operated systems.
The LT3757/LT3757A feature soft-start and frequency
foldback functions to limit inductor current during start-up
and output short-circuit. The LT3757A has improved load
transient performance compared to the LT3757.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
and No R_SENSE and ThinSOT are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
Typical Application
High Efficiency Boost Converter
V_IN
8V TO 16V
10µF
25V ^200k
V_IN
X5R
SHDN/UVLO
10µH
43.2k
LT3757
SYNC
GATE
226k
41.2k
300kHz
RT
SS
V_C
SENSE
FBX
GND INTV_CC
+ 47µF
35V
×2
0.1µF
22k
6.8nF
4.7µF
10V
X5R
0.01Ω
16.2k
V_OUT
24V
2A
10µF
25V
X5R
3757 TA01a
Efficiency
100
90
V_IN = 8V
80
V_IN = 16V
70
60
50
40
30
0.001
0.01
0.1
1
OUTPUT CURRENT (A)
10
3757 TA01b
3757afd
1