LT3511_15 Datasheet, PDF (1/26 Pages) Linear Technology – Monolithic High Voltage Isolated Flyback Converter

LT3511
Monolithic High Voltage
Isolated Flyback Converter
FEATURES
n _{4.5V to 100V Input Voltage Range}
n _{Internal 240mA, 150V Power Switch}
n _{Boundary Mode Operation}
n _{No Transformer Third Winding or}
Opto-Isolator Required for Regulation
n _{Improved Primary-Side Winding Feedback}
Load Regulation
n _{VOUT Set with Two External Resistors}
n _{BIAS Pin for Internal Bias Supply and Power}
Switch Driver
n _{No External Start-Up Resistor}
n _{16-Lead MSOP Package}
APPLICATIONS
n _{Isolated Telecom Power Supplies}
n _{Isolated Auxiliary/Housekeeping Power Supplies}
n _{Isolated Industrial, Automotive and Medical Power}
Supplies
DESCRIPTION
The LT^®3511 is a high voltage monolithic switching regula-
tor specifically designed for the isolated flyback topology.
No third winding or opto-isolator is required for regula-
tion as the part senses output voltage directly from the
primary-side flyback waveform. The device integrates a
240mA, 150V power switch, high voltage circuitry, and
control into a high voltage 16-lead MSOP package with
four leads removed.
The LT3511 operates from an input voltage range of 4.5V
to 100V and delivers up to 2.5W of isolated output power.
Two external resistors and the transformer turns ratio
easily set the output voltage. Off-the-shelf transformers
are available for several applications. The high level of
integration and the use of boundary mode operation results
in a simple, clean, tightly regulated application solution to
the traditionally tough problem of isolated power delivery.
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and No R_SENSE is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents, including 5438499, 7471522.
TYPICAL APPLICATION
48V to 5V Isolated Flyback Converter
V_IN
36V TO 72V
1μF _1M
V_IN
EN/UVLO
4:1
t
300μH
19μH
43.2k
t
LT3511
169k
R_FB
R_REF
10k
T_C
VC
SW
GND BIAS
69.8k 16.9k
3.3nF
4.7μF
3511 TA01a
V_OUT+
5V
0.3A
22μF
V_OUT–
Output Load and Line Regulation
5.25
5.20
5.15
5.10
5.05
5.00
4.95
4.90
4.85
4.80
4.75
0
V_IN = 48V
V_IN = 36V
V_IN = 72V
50 100 150 200 250 300
LOAD CURRENT (mA)
3511 TA01b
3511fc
1