Many power supplies create their 3.3 V output by down-regulating their 5 V rail, or create 5 V output by down-regulating their 12 V rails. The two rails involved are labeled on the power supply with a combined current limit. For example, the 5 V and 3.3 V rails are rated with a combined total current limit. I am building a power supply with LM723 and my intention is to have 0-30V and a range of 0-5A variable. I am regulating voltage normally, however for current limiting, if I want to regulate small current amounts like 10mA, 100mA I need a shunt resistor with high value, which is not viable for 5A, since with LM723 I need a 0.67V voltage drop to limit current. But we were not able to choose the "current limited DC voltage source" models/symbols. Could you please provide suggestions or symbols and circuits to have a input voltage source with power limit. Input DC voltage source should have 24V, 1A. i.e 24W. Can we just have a ideal voltage source with internal series resistance of 24Ohm. power supplies. Over current can severely damage circuits and integrated circuits. rendering the device inoperable. Current limiting circuitry is a simple way of protecting. circuits from high currents, while allowing high current devices to draw high current. form the same power supply. The power supply has to lower the voltage to keep the current at the limit, when the current limit is reached. If the voltage were to keep rising then the current limit you set would be violated. Imagine if you had a simple resistive load. If the voltage goes up so does the current. So in order for the power supply to maintain the max allowed Figure 1 Inrush current limiting in a switch-mode power supply PTC Inrush Current Limiters Product Portal Application: Inrush current limiting for industrial inverters is robust, and its speed depends on the frequency of the power supply. Inverters are used to control the speed of induction motors. Such variable frequency drives (VFDs power supply - Current limiting using P-CH MOSFET - Electrical Engineering Stack Exchange. Current limiting using P-CH MOSFET. Ask Question. Asked 6 years, 7 months ago. Modified 6 years, 3 months ago. Viewed 8k times. 1. I am currently building variable voltage/variable current (lab) power supply out of an ATX switching power supply. I have been experimenting with simulating current limiting circuits. I am trying to limit current to ~500mA given a fixed 4.8V source. I started a question based on a conventional 2-transistor current limiting circuit over here based on the following schematic . . .. Rather than make that question more convoluted, I thought I would ask a separate question to determine what the difference is Because of the power dissipation capability of 2N3055 transistor, at the worst case that the load is shorted to ground (zero resistance), if you limit the current to 8.4 A then the circuit can handle maximum source voltage of 14V, while limiting the current at 4.2A can handle up to 27V source voltage. The current limit value is the crossover point between CV and CC mode. Meaning, if a load connected to the power supply draws or needs to draw more current than the limit, the supply will automatically go into CC mode, giving the supply current control of the power output. For example, suppose the power supply is set to 5 V and current limit is d8zY4.