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Vox Power Limited | Unit 2, Red Cow Interchange Estate, Ballymount, Dublin 22, D22 Y8H2, Ireland | T +353 1 4591161 |
DOC-MN-008-03, VCCS300 User Manual
Product Operation
System overview
The diagram below outlines the topology and major internal components of a VCCS300 power supply.
The AC mains is fused, filtered, and rectified before being boosted to an appropriate DC voltage. Protection is provided from AC line disturbances and excessive EMI
emissions. The integrated EMI filter attenuates high frequency current emissions to levels below EN55022 class B. It also provides dual pole fusing, one fuse in each
conductor and protection from line disturbances as outlined in EN61000.
Inrush current is controlled by a resistive element upon initial connection to the AC line. Once the internal capacitances have been charged, the resistive element is
bypassed to reduce losses. Note that the inrush specification in the datasheet is given at 25°C, cold start. Inrush current will increase for temperatures above 25°C and
re-application of AC mains.
Active Power Factor Correction (PFC) is used to ensure an accurate input current waveform with extremely low harmonic content, exceeding the requirements of
EN61000-3-2. This stage also provides active input current limiting which prevents overloading of the input stage while maintaining high power factor.
The output of the PFC stage charges the hold-up electrolytic capacitors which store enough energy to allow the VCCS300 product to continue operating during
minor line disturbances. Long lifetime and high temperature capacitors are used which ensures extended lifetime and product reliability.
A highly efficient zero voltage switching circuit is used to drive the LLC transformer from the hold-up capacitors. The output synchronous rectifiers connect to the
transformer secondary and provide safe isolated power. This power converter is controlled using the latest analog control technology to produce superior output
performance in a miniature size.
