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• Onboard2.5A,60VIntegratedPowerSwitch

• NoTransformer,ThirdWindingorOpto-IsolatorRequiredforFeedback

• Current-ModeControl

• Boundary-ModeOperation

• Off-the-ShelfTransformers

• ProgrammableSoft-Start

• ProgrammableUndervoltageLockout

• OutputVoltageTemperatureCompensation

• AdjustableCurrentLimit

The LT3575 is an isolated monolithic flyback switching regulator

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 LT3575 operates over a 3V to

40V input voltage range, has a 2.5A power switch and delivers up

to 14 Watts of output power.

The LT3575 operates in boundary mode, which is a variable

frequency current-mode control switching scheme, typically

resulting in ±5% 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 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 LT3575 is available in a small thermally enhanced TSSOP-16

package and is offered in an extended and industrial operating

junction temperature range from -40°C to 125°C.

• NoOpto-Isolator,TransformerorThirdWindingRequiredforFeedback

• DrivesExternalN-channelPowerMOSFET

• CurrentModeControl

• BoundaryModeOperation

• Off-the-ShelfTransformers

• ProgrammableSoft-Start

• ProgrammableUndervoltageLockout

• OutputVoltageTemperatureCompensation

The LT3748 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 LT3748 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.

The LT3748 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 LT3748 is available in a small MSOP-16 package with

4 pins removed for additional high voltage pin spacing.