Controllable constant current source

摘要

In known constant current sources constructed with operational amplifiers, the resistance value of the load resistance is limited to a limit value which corresponds to the quotient of the amount of the operating voltage and a selected constant current. It is intended to achieve a greater limit value of the load resistance with the least possible additional circuit complexity. In the proposed circuit, the voltage at the non-inverting input of the operational amplifier proportionally tracks the control voltage. The dividing ratio of the voltage divider between the control voltage terminal and reference potential is dimensioned in such a manner that the voltage drop across the resistance between non-inverting input of the amplifier and reference potential becomes very small as a result of which the limit value for the load resistance is almost doubled. The invention finds a particularly advantageous application in feeding current to a Peltier element.