Comparative Analysis of Linear Regulator and Switching Regulator

    Linear regulators use transistors or FETs operating in their linear region to subtract excess voltage from the applied input voltage to produce regulated output voltage. The so-called voltage drop voltage refers to the minimum value of the difference between the input voltage and the output voltage required by the voltage regulator to maintain the output voltage within 100mV above or below its rated value. LDO (low voltage drop) voltage regulator with positive output voltage usually uses power transistor (also known as transfer device) as PNP. This transistor allows saturation, so the voltage regulator can have a very low voltage drop, usually about 200mV; In contrast, the voltage drop of traditional linear regulator using NPN composite power transistor is about 2V. Negative output LDO uses NPN as its transmission device, and its operation mode is similar to that of PNP device with positive output LDO.

    The switch regulator uses the output stage to repeatedly switch the "on" and "off" states, and together with the energy storage components (capacitors and inductors) to generate the output voltage. Its adjustment is realized by adjusting the switching timing according to the feedback sample of the output voltage. In a fixed-frequency regulator, the switching timing is adjusted by adjusting the pulse width of the switching voltage, which is called PWM control. In a gated oscillator or pulse mode regulator, the width and frequency of the switching pulse remain constant, but the "on" or "off" of the output switch is controlled by feedback. According to the arrangement of switches and energy storage components, the output voltage generated can be greater than or less than the input voltage, and multiple output voltages can be generated by one regulator. In most cases, under the same input voltage and output voltage requirements, pulse (step-down) switching voltage regulator is more efficient than linear voltage regulator in converting power supply.

    The advantages of linear DC voltage stabilizer are high stability, small ripple, high reliability, and easy to be made into multiple output continuously adjustable power supply. The disadvantages are large volume, bulky and relatively low efficiency. There are many kinds of regulated power supply, which can be divided into regulated power supply, stabilized current power supply and regulated current (bistable) power supply that integrates regulated power supply and stabilized current. From the output value, it can be divided into fixed output power supply, band switch adjustment type and potentiometer continuously adjustable type. From the output indication, it can be divided into pointer indication type and digital display type.

    The switch-type voltage stabilizer is directly rectified to obtain high voltage DC, and the output voltage is adjusted by controlling the on-off time ratio of the switch tube by the high-frequency oscillator. Switched power supply circuits are divided into series and parallel types. The advantage of switching regulated power supply is high efficiency, because the power consumed by the transistor itself in the switching state is very small, which can reach 70-80% or even higher efficiency, and there is no step-down transformer. Its output transformer is far less than 50 Hz power frequency transformer because it works at high frequency. So the circuit of switching power supply is small and light. The switching voltage regulator can work normally in a large voltage range.

    The switch regulator is a kind of regulated power supply different from the linear regulator. Its circuit types mainly include single-end flyback, single-end forward, half-bridge, push-pull and full-bridge. The fundamental difference between it and linear power supply is that the transformer in the circuit does not work at the power frequency, but works at tens of kilohertz to several megahertz. The power transistor does not work in the linear region, but in the saturation and cut-off region, that is, it works in the switching state; The switching DC regulated power supply is also named after it.

    Whether it is a linear regulator or a switching regulator, their daily maintenance should start from the following aspects:

    1. Regularly observe whether the cooling fan and transmission mechanism of the pressurizer operate normally, check whether the input voltage and load exceed the rated range, and timely handle any abnormality found.

    2. Maintain the voltage stabilizer once a month:

    1) Carefully clean all parts, especially the carbon brush, and contact the exposed part of the coil to remove dirt;

    2) Check whether the internal parts and wire ends of the voltage regulator are loose, and deal with the loose connection or poor contact in time;

    3) Replace the worn or damaged carbon brush in time, and repair or replace the faulty or damaged components in time.

    The above is the knowledge about linear voltage regulator and switching voltage regulator, which is divided for you today. I hope it can give you a reference in the future.