Figure 1).
The load current results in a voltage on the sense resistor ROUT is the output voltage. You can apply the output voltage as a control voltage to regulate the load current.
One application for this circuit would be to refill accumulators in portable devices. In this case, the circuit works at 18V. The .
equation, you can calculate the four weighting resistors of the three BCD switches, which you can determine when the current flows through only that resistor. For currents of 800, 400, 200, 100, 80, 40, 20, 10, 8, 4, 2, and 1 mA, the corresponding resistances would be 0.125, 0.25, 0.5, 1, 1.25, 2.5, 5, 10, 12.5, 25, 50, and 100 kΩ. If the load current is 1A, then the output current is only 1 mA, and, if the load current is 1 mA, then the output current is only 1 μA. Note that the IRF520’s surface is on the drain potential.