Archive for July, 2010

Switching Mode Power Supplies

A problem of linear power supply is the size and weight of the transformer. The size is required because of the low frequency (50 to 60 Hz). For the same power output, the transformer size goes down as the frequency goes up (up to a point). The SMPS takes advantage of this by chopping the [...]

Linear Regulation

The principle of operation of a linear regulation power supply is shown in the following diagram:

Glossary of power supplies (3)

Minimum load: If specified for a power supply, it is the minimum load current that must be drawn from the power supply so that it meets its performance specifications. Surge: A momentary increase in the AC power line voltage. Output impedance: The ratio of a change in output voltage to a change in load current. [...]

Glossary of power supplies (2)

AC: Alternating current. Describes voltage and current that varies in amplitude, usually in a sinusoidal waveform with respect to time. AC power is almost universally used for distributing electrical power. Blackout: Loss of AC electrical power. Brownout: A planned AC voltage reduction by the power company to counter excessive demand.

Glossary of power supplies (1)

Here is some Glossary of power supplies: Line regulation: How much the load voltage or current changes when the power supply isoperated at varying line voltages throughout a given range. Typically stated as a percentage of the total voltage or current available from the supply. A rating of “0%” would mean perfect regulation. Load regulation: [...]

Why is there such a big difference in price between power supplies?

A Related question can be asked about automobiles. Both questions have the same answer: there are many factors at play and a simple answer is probably not possible. Many of the factors are: Marketer name and reputation Design of the power supplies Number and type of competitive units Certifications (such as safety, EMI, etc.) Dependability [...]

How to measure power supply efficiency ?

If efficiency is significant to you, you will need to evaluate it carefully. For a regular DC power supply operated from the AC line, you will need to measure the input AC power and the DC power being output by the supply as in the following plot:

What is Switching power supplies

Switching power supplies, switched mode power supply, SMPS, is basically an electronic power unit that has a switching regulator. Why we need a switching regulator? The switch mode power supply quickly switches a power transistor between on and off. What is the advantage of this? The main advantage of SMPS is that the switching transistor [...]