Power Supply Circuit Varieties


In the realm of semiconductors, power supply circuits play a pivotal role. These intricate components are tasked with delivering the essential power required for device functionality, facilitating a plethora of applications while ensuring efficiency, steadfastness, and trustworthiness. Let’s delve into four distinct types of power supplies commonly utilized in circuits: unregulated, linear-regulated, switching, and ripple-regulated.

Crafted to metamorphose electrical energy for a load, power supply circuits furnish semiconductor devices with indispensable power, ensuring both stability and reliability. Each power supply encompasses three vital constituents:

  • The Input Power Supply: This component furnishes electricity at a specific voltage or voltage range.
  • The Load: It necessitates a supply of electricity delivered at a designated voltage or voltage range.
  • Circuitry for Conversion: This circuitry receives input voltage and outputs voltage accordingly.


Switch Regulated Power Supplies

Switch Regulated Power Supplies, colloquially known as “Switchers,” amalgamate the virtues of linear regulated and unregulated supplies. Despite their compact size, these power supplies offer economic viability and efficiency, resulting in a consistent, untainted output voltage.

Switchers employ transistors as on/off switches to rectify incoming AC power line voltage into DC. Subsequently, they reconvert the DC into high-frequency square-wave AC. Finally, a lightweight transformer steps the AC voltage up or down, rectifies the transformer’s AC output into DC, and filters the final output.

What distinguishes Switchers from other power supplies is their universal compatibility. They can function independently of input voltage, making them compatible with any electric power system. However, a notable drawback of Switchers is the generation of high-frequency AC “noise” on the power line, potentially resulting in increased ripple voltage and noise levels, contingent upon the power supply’s quality.


Unregulated Power Supplies

Among all power supplies, Unregulated Power Supplies represent the most rudimentary form. Simple and straightforward, these supplies comprise a transformer, rectifier, and low-pass filter. While they offer reliable performance at an economical price point, unregulated supplies may encounter issues with ripple voltage and AC noise, leading to varying degrees of instability when superimposed on DC power.


Linear Regulated Power Supplies

A Linear Regulated Power Supply is essentially an unregulated power supply followed by a transistor circuit operating in “active” or “linear” mode. Commonly referred to as “brute force,” these power supplies convert AC to DC while maintaining a constant output voltage. However, their efficiency is compromised as excess voltage is dissipated as heat to maintain the desired output voltage.

The mechanism behind Linear Regulated Power Supplies involves providing a fixed voltage output for a wide range of input voltages, dissipating any excess input voltage to ensure a maximum output voltage to the load. The dissipation of excess voltage generates heat, necessitating the input voltage to be 1 to 3 volts higher than the desired output. Consequently, these power supplies tend to be larger and heavier than their counterparts to accommodate heat dissipation.


Ripple Regulated Power Supplies

The “front end power supply” of a Ripple Regulated Power Source comprises a transformer, rectifier, and filter. However, what sets this power source apart is its additional alternative power supply – a transistor employed solely to utilize its saturation/cutoff modes for transferring DC power to a large capacitor as required to maintain the output voltage within a predefined range. As a result, minimal energy is lost as heat.

Since ripple regulator circuits do not need to endure the same voltages as switcher transistors, they are safer to work with and often boast simpler circuitry compared to switcher circuits.