Adjustable power adapter related technology

　　Adjustable power adapter related technology

　　Adjustable linear power adapter

　　What the power adapter manufacturer introduces here is that the adjustable linear power adapter that is rarely mentioned in the switching power adapter materials is due to the following reasons.

　　First, when very low output noise is required, the linear regulator is still the best choice. Second, the "cascaded" linear system described here is a very practical but somewhat overlooked technology. Finally, the shortcomings of high energy consumption and low efficiency of energy-consuming linear regulators just illustrate the advantages of the adjustable switching power adapter described in the next chapter.

　　In this section, we review the basic concepts of adjustable linear digital camera power adapters in laboratory applications. In addition to the lower loss of fixed voltage linear regulators, the main principles are the same. For its advantages, the linear regulator itself The noise level is low, usually measured in microvolts, rather than the millivolts commonly used in switching systems.

　　For those applications where the minimum electronic noise level is a basic requirement (such as sensitive communication equipment, research activities), the advantages of the very low noise level of energy-consuming linear regulators are usually more important than the highest efficiency requirements.

　　A well-designed linear regulator can have a transient response time of 20p when it is fully restored, while a typical switching regulator is 500µs.

　　The biggest disadvantage of the linear regulator is that it must dissipate the difference between the output power (VA) and the internally generated power as heat energy. This dissipated power will be very large, reaching the maximum value at high output current and low output voltage.

　　In the example given here (a 60V, 2A adjustable power adapter), the minimum unadjustable 1A power adapter voltage is 70V. When a 2A load is applied (when the output is short-circuited), the output voltage is set to 0, and the minimum power consumed by the normal series regulator is 140W. If this energy is concentrated on the transistors of the series linear regulator, an expensive heat sink and Quality control.https://powerstation-gf.com/prodcuts/SPS-001-wall-mounted-home-energy-storage_283.html

　　A method of pre-regulating the secondary side. This method allows most of the excess energy to be consumed on the passive resistance instead of on the transistor of the series regulator. The advantage of consuming this energy by the resistance is that the high-quality winding resistance can be compared with Semiconductor devices operate at higher surface temperatures, so they can consume excess energy more efficiently. Smaller airflow can effectively take away the excess heat, and the cost of the resistor is lower than that of the additional adjusting product tube and radiator. The energy-consuming resistor can be placed outside the main components of the power adapter, which greatly reduces the volume of the power adapter device. Small, and will not produce excessive temperature rise in internal mail. Finally, inexpensive linear regulator quality tubes and smaller heaters can be used.

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