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Switching Power supply

Switching Power supply

Switching Power supply

What makes the difference between switching mode power supply  and a simple power supply unit? i tried to google yet i can't find good  literature to define it. anyone could share his expert understanding?

"..the more, the merrier" Genghis Khan


RE: Switching Power supply

A conventional linear supply basically arranges to suck up the voltage drop between the input voltage and the regulated voltage, and dissipate the v_drop * i_load power.  In some cases, the designer is willing to allow that, but in other cases, the wasted power and generated heat may be prohibitive, so switching power supplies are used.  If the input voltage is very high, the power supply efficiency could be as low as 5%.

A switching power supply could be very loosely viwed as a DC-DC transformer.  It basically packetizes chunks of power at v_in*i_in and transforms the packet into v_out*i_out.  The efficiency of the transformation can be as high as 90%.


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RE: Switching Power supply

Also, as the power level goes up a linear supply gets larger and very much heavier, rapidly, as compared to a switcher.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Switching Power supply

On the other hand, linear power supplies typically have very low noise other than some low-level ripple at 2x line frequency (or at 6x line frequency if it's a big one with a 3-ph input). Switchers are inherently noisy and it takes a lot of effort to make a switcher 'quiet'. There are some good ones, but most are designed to meet the EMC regulations and not be a low-noise supply.

If we learn from our mistakes I'm getting a great education!

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