Sunday 20 November 2011

Switched Mode Power Supply

Switched Mode Power Supply (smps)

SMPS stands for Switched Mode Power Supply or switching-mode power supply.
SMPS is a power supply (PSU) for electronic use, which contains a switching regulator. While a linear regulator maintains the desired output voltage by spreading the excess current in a "pass" power transistor, the SMPS switches a power transistor to rapidly between saturation (full on) and cutoff (completely off) with a variable duty cycle whose average is the desired output voltage. This process gives rectangular waveform as a result which is filtered by a low-pass filter with an auxiliary coil and capacitor.
The top benefit of using this process in SMPS is that it gives a better performance. It is because of the small dispersion of power by switching transistor in the saturated and off mode compared to the semiconducting state (active region). Other benefits of Switch Mode Power Supply (SMPS) includes smaller size and lower weight which is larger in low frequency transformers which have a high weight. Furthermore, it generates less heat from the higher efficiency.
Disadvantages of SMPS

*Greater complexity
*The generation of high amplitude
*High-frequency energy, low-pass filter must block to avoid
*Electromagnetic interference (EMI)
*Ripple voltage at switching frequency and harmonic frequencies ..
*SMPS can be categorized into four types based on its input and output waveforms, as follows.
*AC in, DC out: rectifier, off-line converter input.

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