# Current limiter for fixed voltage output

I need to design a current limiter for a circuit. I haven't started to design it so I cannot show the schematics, but I'll try to explain it.

It consists just in 2 light sensors. These sensors send a value to an MCU. The supply voltage is 12V but is lowered to 5V for the electronics. The important thing is here:

Depending on the values of the sensors (This corresponds to de programmable part of the MCU) I'll need to have a -1.5V, 0V or 1.5V output value. This is, -1.5V and 1.5V will supply the load, and 0V just won't do anything. The maximum Amperes value must be around 200mA or a bit lower.

So, I ask if you know any component-circuit that could suit this requirements.

UPDATE --

According to the comments, I'll update the post with few more data.

The functionality must be like, if sensor1 < sensor2 then output is -15V, and if sensor1 > sensor2 output 1.5V.

But I still have some things in the air that I need to define:

• I could use a voltage regulator to low the voltage from 5V to 1.5V, but then, I'll need to define how I generate the negative voltage.
• I need to set how the MCU tells if the output is negative or positive
• I need to define the current limiter. I found components like this, but this one has reverse-voltage protection so maybe for this purpose is not the best option
• Do I get it right, that you need to limit the absolute value of current on -1.5V to +1.5V rail? – Dzarda May 6 '14 at 9:01
• You should try and formulate your exact requirements. If incident light is above X then output is Y. If incident light is below Z then output is -Y etc.. – Andy aka May 6 '14 at 9:02
• Add a negative voltage generator and use comparators - get rid of the MCU - it isn't bringing anything to the party as far as I can tell. – Andy aka May 6 '14 at 9:53
• What do you need that +/- 1.5V for? There might be an easier way to get the effect you want. – Wouter van Ooijen May 6 '14 at 10:22
• Can you drive your load with full bridge, e. g. +1,5 V on 'negative' load rail, instead of generating negative voltage? This could simplify your task a lot. – Vovanium May 6 '14 at 11:45