Difference between linear and switching regulators

Discussion in 'General Electronics Chat' started by RRITESH KAKKAR, Mar 22, 2011.

  1. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    What is the difference in linear & switching regulators??
     
  2. RRITESH KAKKAR

    Thread Starter Senior Member

    Jun 29, 2010
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    Please, reply.
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
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  4. tom66

    Senior Member

    May 9, 2009
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    A switching regulator transfers charge between an inductor and capacitor at such a rate to increase, decrease or invert a voltage. It works by creating a magnetic field in the inductor and using clever control electronics it regulates the voltage. There are also regulators which use transformers, and technically charge pumps can be considered a type of switching regulator, but using capacitors instead. A good switching regulator will run from about 75% to 90% efficiency. Charge pumps are ideal, approaching 99% efficiency, but output current is often limited to a few hundred mA at best, and switching noise can be an issue.

    A linear regulator works kind of like a series resistor. To drop voltage it dissipates heat. The amount of power wasted, in watts, is approximately (Vin-Vout)*Iout. A linear regulator can ONLY step down voltage.

    Linear regulators are by far easier to design for. However, they can be tricky if they are small - thermal management (keeping it cool) can become a real issue.

    Now, that's not to say a (step-down) switching regulator is more efficient than a linear regulator. In certain circumstances, for example low current drain or a small Vin-Vout differential, an LDO can outperform a switcher. A low dropout regulator dropping 0.5V (from 5.5V to 5V) and delivering 100mA would only dissipate 50mW, to provide 500mW - around 90% efficiency.
     
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