Switch-mode power supplies can now be found in most PC’s, power amplifiers, TV’s, dc motor drives, etc., and just about anything that requires a highly efficient supply as switch-mode power supplies are increasingly becoming a much more mature technology.īy definition, a switch mode power supply (SMPS) is a type of power supply that uses semiconductor switching techniques, rather than standard linear methods to provide the required output voltage. Switch Mode Power Supplies, or SMPS, are becoming common place and have replaced in most cases the traditional linear AC-to-DC power supplies as a way to cut power consumption, reduce heat dissipation, as well as size and weight.
When higher output voltage or current power demands are required, the normal practice is to use a switching regulator commonly known as a switch-mode power supply to convert the mains voltage into whatever higher power output is required.
#Isolated cuk converter voltage regulator series#
Since all of the load current must pass through the series transistor, this results in a poor efficiency, wasted V*I power and continuous heat generation around the transistor.Īlso, one of the disadvantages that series voltage regulators have is that their maximum continuous output current rating is limited to just a few amperes or so, so are generally used in applications where low power outputs are required. While this simple series regulator circuit will work, the downside to this is that the series transistor is continually biased in its linear region dissipating power in the form of heat. Then depending upon the value of the base voltage, any value of emitter output voltage can be obtained. Since a transistor provides current gain, the output load current will be much higher than the base current and higher still if a Darlington transistor arrangement is used.Īlso, providing that the input voltage is sufficiently high enough to get the desired output voltage, the output voltage is controlled by the transistors base voltage and in this example is given as 5.7 volts to produce a 5 volt output to the load as approximately 0.7 volts is dropped across the transistor between the base and emitter terminals. As an emitter follower circuit has unity voltage gain, applying a suitable biasing voltage to the transistors base, a stabilised output is obtained from the emitter terminal. Here this simple emitter-follower regulator circuit consists of a single NPN transistor and a DC biasing voltage to set the required output voltage. Then a typical DC power supply would look something like this: Typical DC Power Supply Most DC power supplies comprise of a large and heavy step-down mains transformer, diode rectification, either full-wave or half-wave, and a filter circuit to remove any ripple content from the rectified DC to produce a suitably smooth DC output voltage.Īlso, some form of voltage regulator or stabiliser circuit, either linear or switching can be used to ensure the correct regulation of the power supplies output voltage under varying load conditions. There are even variable voltage linear regulators available as well providing an output voltage which is continually variable from just above zero to a few volts below its maximum voltage output. This allows us to create a whole host of different power supply rails and outputs, either single or dual supply, suitable for most electronic circuits and applications. There is a wide range of these three-terminal fixed voltage regulators available each with its own built-in voltage regulation and current limiting circuits. These two types of complementary voltage regulators produce a precise and stable voltage output ranging from about 5 volts up to about 24 volts for use in many electronic circuits. The most popular linear and fixed output voltage regulator types are by far the 78… positive output voltage series, and the 79… negative output voltage series. Linear voltage regulators are generally much more efficient and easier to use than equivalent voltage regulator circuits made from discrete components such a zener diode and a resistor, or transistors and even op-amps.