# Ideal Current Source

An **Ideal Current Source** has several properties which allow the current source to always deliver the **rated current** to the circuit **independent **of the circuit **resistance** and **voltage** across its terminals.

These properties are:

- Has the
**same current flowing through it regardless of the voltage across its terminals** - Can supply a
**specified current to any circuit element connected to it** - It has the
**voltage necessary**to provide the**rated current**

The typical case is shown below:

The current source, **Is**, provides 1mA which flows through the 3.3kΩ resistor resulting in a 3.3V voltage drop across it.

One of the edge cases is shown below. This is a **short circuit:**

Current still flows in the circuit shown above, it doesn't care if there is a 0V drop across the circuit (recall it has the same current flowing through it **regardless of the voltage across its terminals**)

The final edge case is shown below. This is an **open circuit:**

This circuit has the following properties:

**This zeroes the effect of an ideal current source****As an open circuit has infinite resistance**and**no current flowing through it**and hence this circuit is**logically impossible (would require the supplied current value to change which breaks the definition of an ideal current source)****Open Circuit => R = ∞Ω**

**Note: In reality, the voltage across the current source would reach a high value (V=IR) to attempt to deliver current to an infinite resistance which will damage the current source (Do not try this at home :) ).**