940622127011 | PHILIPS POWER SUPPLY

For many years the world of power supply design has seen a gradual movement away from the use of linear power supplies to the more practical switched mode power supply (S.M.P.S.). The linear power supply contains a mains transformer and a dissipative series regulator. This means the supply has extremely large and heavy 50/60 Hz transformers, and also very poor power conversion efficiencies, both serious drawbacks. Typical efficiencies of 30% are standard for a linear. This compares with efficiencies of between 70 and 80%, currently available using S.M.P.S. designsFurthermore, by employing high switching frequencies, the sizes of the power transformer and associated filtering components in the S.M.P.S. are dramatically reduced in comparison to the linear. For example, an S.M.P.S. operating at 20kHz produces a 4 times reduction in component size, and this increases to about 8 times at 100kHz and above. This means an S.M.P.S. design can produce very compact and lightweight supplies. This is now an essential requirement for the majority of electronic systems. The supply must slot into an ever shrinking space left for it by electronic system designers