LT3748 Datasheet, PDF (1/28 Pages) Linear Technology – 100V Isolated Flyback Controller

LT3748
100V Isolated
Flyback Controller
Features
n _{5V to 100V Input Voltage Range}
n _{1.9A Average Gate Drive Source and Sink Current}
n _{Boundary Mode Operation}
n _{No Transformer Third Winding or Opto-Isolator}
Required for Regulation
n _{Primary-Side Winding Feedback Load Regulation}
n _{VOUT Set with Two External Resistors}
n _{INTVCC Pin for Control of Gate Driver Voltage}
n _{Programmable Soft Start}
n _{Programmable Undervoltage Lockout}
n _{Available in MSOP Package}
Applications
n _{Isolated Telecom Converters}
n _{High Power Automotive Supplies}
n _{Isolated Industrial Power Supplies}
Description
The LT^®3748 is a switching regulator controller specifically
designed for the isolated flyback topology and capable of
high power. It drives a low side external N-channel power
MOSFET from an internally regulated 7V supply. No third
winding or opto-isolator is required for regulation as the
part senses the isolated output voltage directly from the
primary-side flyback waveform.
The LT3748 utilizes boundary mode to provide a small
magnetic solution without compromising load regulation.
Operating frequency is set by load current and transformer
magnetizing inductance. The gate drive of the LT3748
combined with a suitable external MOSFET allow it to
deliver load power up to several tens of watts from input
voltages as high as 100V.
The LT3748 is available in a high voltage 16-lead MSOP
package with four leads removed.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 5438499 and 7471522.
Typical Application
25W, 12V Output, Isolated Telecom Supply
V_IN
36V TO 72V
4:1
10µF
412k
EN/UVLO ^VIN
15.4k
LT3748
R_FB
R_REF
60.8µH
243k
6.04k
3.8µH
56.2k
TC
GATE
SS
SENSE
V_C
GND INTV_CC
2nF 10k
4700pF
4.7µF
0.033Ω
3748 TA01a
V_OUT+
12V
2A
100µF
V_OUT–
Output Load and Line Regulation
12.6
14.4
12.2
12.0
11.8
11.6
11.4
0
V_IN = 72V
V_IN = 48V
V_IN = 36V
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
3748 TA01b
3748f