22 February 2021

Difference between Linear Supply and Switch Mode Power Supply

The linear power supply and the SMPS of the switch both supply electrical and electronic circuits with DC power, but the similarities end here. The working procedure is the crucial factor that distinguishes linear power and SMPS. The linear supply converts high voltage AC into the low voltage using a transformer and then converts it into DC voltage while the SMPS converts AC into DC first the transforms that DC voltage into desired voltage.

What is liner supply?

The Linear supply power supplying circuit which is used in electrical and electronics circuit to supply the DC power to the circuit. It consists of a step-down transformer, rectifier and filter circuit, regulator.

What is a Switch mode power supply?

The SMPS operated on the principle of switching using a MOSFET transistor. It consists of a rectifier circuit, filter circuit, chopper controller, and output transformer. 

 Difference between linear supply and switch-mode power supply:

  • Linear supply completes the stepping down of AC voltage first then it converts it into DC, while the SMPS is converted the input signal down the voltage up to the desired level.
  • Linear supply is low efficiency about 20-25%, but the SMPS is high efficiency about 60-65%.
  • Stalley or CRGO core is used for Linear supply while the SMPS used for magnetic materials used for ferrite.
  • Linear supply is bulky, while the SMPS is less bulky in comparison to the linear power supply.
  • Voltage regulation is done by voltage regulator in liner supply, while voltage regulation is done by a feedback circuit in SMPS.
  • Linear supply is complex than SMPS, while SMPS is more complex than linear supply.
  • Linear supply is more reliable in comparison to SMPS, while the SMPS reliability depends on the transistor used for switching.
  • No RF interference in linear supply, while the SMPS the RF shielding is required as switching produces more RF interference.
  • Linear supply is immune to noise and electromagnetic interference, while the SMPS effect noise ad electromagnetic interference is quite significant, thus EMI filters are required.
  • Linear supply used in audio frequency applications and RF applications, while the SMPS used in chargers of mobile phones, DC motors, etc.