LT3757 as SEPIC Converter

[polfort]

Hello.

If You look at Page 32 of this Datasheet: http://cds.linear.com/docs/Datasheet/3757fa.pdf, there is the LT3757 as a SEPIC Converter, delivering +-0.4A at +-12V.

Could You tell me if it΄s possible to get +-50mA at +-45V out of that Circuit?
The datasheet says that a voltage divider in the back loop sets the output Voltage.
I dont think this could be so simple only to adjust the Values of the voltage divider to get my desired Output.

If that would be possible, how could I achieve this using the circuit on page 32?


Best regards.
polfort

[Alex Tsekenis]

It is posible as the IC acts just as the controller in the circuit. The power switch, voltage divider, current sense, inductors,capacitors are external so by recalculaing their value (full details in the datasheet) you will be able to produce your required output.

Also have a look at this app. note:

http://www.national.com/an/AN/AN-1484.pdf

You could use the output divider to tweak the output voltage but vary it over such a range.

Also you can use LTSPICE to simulate it.

[polfort]

Thank You.
Especially for that Application Note. Which is very useful and helps to calculate the proper values.
Besides it makes clear the functionality of a SEPIC converter in detail

Best regards,

polfort