help me to design const ct source?

[niks]

Hi ,
i want to design 20mA const current source. But my supply(Battery) is varing from 3.45 to 2.2 V .... How can i maintain same current at all voltage levels? This ckt will be on for few mS/day . so during off state leakage current should be very small.say less than 1uA.
anyone can hlp me to design?

 

[samsuffy]

TI provides an IC with a current mirror and a 100uA current source embedded : see for REF200 component.

It's maybe a quick'n'dirty solution but it should meet your requirements.

 

[brmadhukar]

Hi,

Can U use a regulator.

Madhukar

 

[andy2000a]

for constant current a simple method use JFET ...

use JFET as diode, and JFET Ids = constant current
but you should be notic input voltage and maker sure JFET still work
well