LT3757 Datasheet, PDF (1/36 Pages) Linear Technology – Boost, Flyback, SEPIC and Inverting Controller

LT3757
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 is a wide input range, current mode, DC/DC
controller which is capable of generating either positive or
negative output voltages. It can be configured as either a
boost, flyback, SEPIC or inverting converter. The LT3757
drives 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 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 ideally suited for battery-operated systems.
The LT3757 features soft-start and frequency foldback
functions to limit inductor current during start-up and
output short-circuit.
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
41.2k
300kHz
43.2k
LT3757
SYNC
GATE
226k
RT
SS
VC
SENSE
FBX
GND INTV_CC
+ 47µF
35V
s2
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
3757fb