Any trick to make a linear regulator go down to 3.3V instead of the ref voltage?

[xReM1x]

hi, for my current sink I use a ref voltage that turns on from the linear supply, the problem is the ref voltage is 3.3V and unfourmently the regulator goes down to 1.2V~ and I need the regulator to go down only to 3.3V~. not less. the regulator is LT1083. I know I could drive a voltage to the adj pin but maybe there is easier way? thanks.

 

[D.A.(Tony)Stewart]

LT1083/4/5 all use Vref =1.250V , so Vo.min=Vref.

If you want to regulate to 0V, you would need a V->=-1.25 to drive Vadj. Low current but stable voltage.

No problem?

 

[xReM1x]

LT1083/4/5 all use Vref =1.250V , so Vo.min=Vref.

If you want to regulate to 0V, you would need a V->=-1.25 to drive Vadj. Low current but stable voltage.

No problem?

But I need it so it will go down to 3.3V and not 0V. also isnt there other options without other -1.25V?

 

[KlausST]

Hi,

Instead of a voltage regulator maybe you could use an opamp.

To check on this we need more data, like current and schematic...

Klaus

 

[xenos]

hi, for my current sink I use a ref voltage that turns on from the linear supply...

Do you use it as a current regulator (so you do not care about the voltage), or a voltage regulator?
Sorry but I did not understand exactly what you would like to do.

If you would like an adjustable voltage regulator that goes from 3,3 and up, then you should use a constant resistor in series with the trimmer resistor. This will limit the bottom limit of output voltage.