In the context of electronics and systems containing Printed Circuit Boards (PCBs), PSU stands for Power Supply Unit.
Understanding What a PSU Is
A Power Supply Unit (PSU) is an essential component in many electronic devices, especially computers and other complex systems that rely on PCBs. Its primary function is to convert the electrical power from an external source into a format that can be used by the internal components.
According to the reference provided, a power supply unit (PSU) "converts mains AC to low-voltage regulated DC power for the internal components of a desktop computer." This is a common and widely recognized role for a PSU. Modern systems, including personal computers, typically use switched-mode power supplies (SMPS) for this conversion due to their efficiency.
Here's a simple breakdown:
- Input: Usually higher voltage Alternating Current (AC) from the wall outlet (mains power).
- Conversion: The PSU processes this AC power.
- Output: Converts it into lower voltage Direct Current (DC) power, typically at several different voltage levels needed by various components (e.g., +12V, +5V, +3.3V).
PSU and its Relation to PCBs
While the PSU itself is often a separate box or module, it directly interacts with PCBs. PCBs are the foundational boards where electronic components like chips, resistors, and capacitors are mounted and interconnected. These components require precise DC voltages to operate correctly.
The PSU is the source that provides these necessary DC voltages to the PCB. Connections from the PSU plug into the PCB (or connector boards attached to the main PCB), delivering power to all the components on the board.
Think of it this way:
- The PSU is the generator or converter of the right kind of power.
- The PCB is the distribution network and the platform where the components that use that power reside.
Without a PSU, the components on the PCB would not receive the power they need to function.
Where Power Lives on a PCB
While the main PSU unit is external to most PCBs (like in a computer), a PCB itself often contains its own power management and regulation circuitry. This circuitry takes the power supplied by the external PSU and further filters, regulates, or distributes it to specific parts of the board or individual components. So, while "PSU" typically refers to the main conversion unit, the PCB often hosts the components that manage power distribution after it arrives from the PSU.
| Term | Definition | Primary Location |
|---|---|---|
| PSU | Power Supply Unit (converts mains AC to regulated DC) | Often a separate unit (e.g., PC case) |
| PCB | Printed Circuit Board (mounts and connects components) | Within the device/system |
In summary, in the context of a PCB, PSU refers to the unit that supplies the necessary DC power to the board and its components, converting it from an AC source.
