Electrical – How to get a LDO voltage under 1.1V with lm1117 adj LDO


I'd like to get voltage under 1.1v with lm1117-adj in 5v input.
The problem is that I don't know, is this possible to get what I want the voltage under 1.1v?


This is what I've got exactly the same schematic.

enter image description here

Best Answer

You could use an LM7705 and three tiny ceramic caps to generate a -0.232 volt negative rail and then you'd be able to get down to about +1V.

\$V_{OUT} = V_{REF} (1 + \frac{R_2}{R_1}) - 0.232 +I_{ADG}R_2\$

So for R2 = 0, Vout ~= 1.02V

enter image description here


simulate this circuit – Schematic created using CircuitLab

Where \$R_2 (\Omega) \approx 96.2(V_{OUT} -1.018)\$

Or use another type of regulator (what I would suggest if the neg rail isn't otherwise useful).

Related Topic