How do you create a stable current source?
So to make a device that provides a constant current no matter the load, we have to use negative feedback and convert the current flowing through our load into a voltage. Luckily, there is a very easy way to convert a current to a voltage which involves using a small ohm resistor (in our case, a 0.1-ohm resistor).
How do you regulate constant current?
Current regulation can be implemented through the addition of an external control loop and current-sense resistor. Such a design must take into account the power limitations of the DC-DC converter and must ensure the stability of the converter’s voltage loop.
How to calculate the constant current in a circuit?
Simple constant current source made from high voltage source and a high value resistor For the circuit above, the current can be calculated very easily as it is approximately I = V / R because Vload (the voltage across the load) is much smaller than V (the voltage of the source). This simple form of current source has many limitations:
How does a constant current source power supply circuit work?
This increase in conduction of Q3 allows more current to flow through the load and the 0.1-ohm resistor. If the current flowing through the resistor goes beyond 1 amp, then the voltage across the 0.1ohm resistor becomes greater than 0.1V.
How does the MOSFET constant current circuit work?
The MOSFET Constant-Current Source Circuit. Here is the basic MOSFET constant-current source: It’s surprisingly simple, in my opinion—two NMOS transistors and a resistor. Let’s look at how this circuit works. As you can see, the drain of Q 1 is shorted to its gate. This means that V G = V D, and thus V GD = 0 V.
What are the limitations of a constant current source?
This simple form of current source has many limitations: 1 The high values of resistance needed dissipate power making circuits inefficient. 2 High source voltages are needed and are not always easily available. 3 Variations in load may cause some current variations if sufficiently high values of source voltage are not available.