Current Sourcing and Sinking
A current source is a component that provides a constant current output, while a current sink absorbs a constant current input. Both are essential for designing circuits with specific current requirements and for ensuring consistent current flows in various electronic systems.
Current sources and current sinks are fundamental concepts in electronics that refer to components or circuits designed to provide or absorb a specific amount of electric current.
Current Source
A current source is an electronic component or circuit element that generates a consistent and constant electric current, regardless of the load connected to it. It is designed to deliver a specific current value without being significantly affected by changes in the load impedance. In other words, it acts as a stable source of current, ensuring that a certain amount of current flows through the circuit even if the resistance of the load changes. Current sources are commonly used in various applications, such as biasing circuits, active loads, and reference current generators.
Example of Current Source
Here’s an example of a configuration: a series resistor and an LED connected between a microcontroller pin and the ground (GND). When the microcontroller pin is set to a high state (logic 1), the microcontroller becomes the current source for the load. In this setup, when logic 1 is applied, power flows into the load (thus turning on the LED). Conversely, when logic 0 is applied, power to the load is cut off (switching the LED off).
Current Sink
A current sink, on the other hand, is an electronic component or circuit element that absorbs or “sinks” a specific amount of electric current. Similar to a current source, a current sink maintains a constant current regardless of changes in the load resistance. It provides a way to control and regulate the flow of current in a circuit by drawing a predetermined amount of current from it. Current sinks are often used in applications such as current mirrors, where they help replicate a certain current for biasing or amplification purposes.
Example of Current Sink
A common instance of current sinking is achieved by connecting a series resistor and an LED between a power source (such as +5V) and a microcontroller pin. When the microcontroller pin is set to a high state (logic 1), the circuit interrupts the current flow to the load. However, when the microcontroller switches the pin low (logic 0), it allows current to pass through the load, lighting up the LED.