Turning lt1308 into current source switching reg.

[foxOnTheRun]

About this Linear Technology - LT1308A/B - Single Cell High Current Micropower 600kHz Boost DC/DC Converter

I'm trying to convert it into a stable (and controllable) current source.

Do you have any suggestion on how to trick it's FB pin and build a suitable current feedback network?

But, more in general, is it possible to turn a generic switching ic. trycking it's voltage feedback pin? (more interested in this answer)

Maybe, could someone of you provide some excerpt from books, theory and so on? I'm finding only some clues via google, but nothing that could boost me inside a real current controlled schema

Thanks.

 

[MikeMl]

About this Linear Technology - LT1308A/B - Single Cell High Current Micropower 600kHz Boost DC/DC Converter

I'm trying to convert it into a stable (and controllable) current source.

Do you have any suggestion on how to trick it's FB pin and build a suitable current feedback network?

But, more in general, is it possible to turn a generic switching ic. trycking it's voltage feedback pin? (more interested in this answer)

Maybe, could someone of you provide some excerpt from books, theory and so on? I'm finding only some clues via google, but nothing that could boost me inside a real current controlled schema

Thanks.

I took the LT1308A test Jig supplied by Linear, and did the obvious thing of using the voltage drop across a sense resistor for the feedback. Note that the internal reference voltage is ~1.2V, so this puts 100mA through the two LEDs. It simulates fine, but you will have to breadboard it. Note the current drawn from the source...

 

[foxOnTheRun]

Thanks! meanwhile I'm doing some homework, here's my first try.. but I'm not getting quite right the feedback network.. still working on it (any suggestion?)

Tnx!

 

[foxOnTheRun]

..Note the current drawn from the source...

Right! and also it's 80% efficient, more or less (taking values from graphs).