100V Isolated Flyback DC/DC Controller Simplifies Design & Eliminates Optocoupler
- VIN Range from 5V to 100V
- No Opto-Isolator, Transformer or Third Winding Required for Feedback
- Drives External N-channel Power MOSFET
- Current Mode Control
- Boundary Mode Operation
- VOUT Set with Two External Resistors
- Off-the-Shelf Transformers
- Programmable Soft-Start
- Programmable Undervoltage Lockout
- Output Voltage Temperature Compensation
The LT3748LT3748 is a high input voltage isolated flyback DC/DC controller that significantly simplifies the design of an isolated DC/DC converter. No opto-isolator, third winding or signal transformer is required for feedback since the output voltage is sensed from the primary-side flyback signal. The LT3748LT3748 operates over a 5V to 100V input voltage range and drives an external N-channel power MOSFET, making it well suited for a wide variety of industrial, medical, telecom, datacom and automotive applications.
LT3748 Schematic
The LT3748LT3748 operates in boundary mode, which is a variable frequency current mode control switching scheme, resulting in ±5% typical regulation over the full line, load and temperature range. Boundary mode also permits the use of a smaller transformer compared to equivalent continuous conduction mode designs. The output voltage is easily set by two external resistors and the transformer turns ratio. Several off-the-shelf transformers identified in the data sheet can be used for numerous applications. The high level of integration and the use of boundary mode operation results in a simple, clean application solution to the traditionally tough problem of isolated power delivery.
Additional features include an onboard low dropout regulator for IC power, programmable soft-start, undervoltage lockout, adjustable current limit and output voltage temperature compensation. The LT3748LT3748 is available in a small MSOP-16 package with 4 pins removed for additional high voltage pin spacing.
More info on www.linear.com/3748 or go to Design Kit Demoboard
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