Comparative Analysis of Linear Regulators and Switching Regulators

1. The different concepts of linear regulators and switching regulators

1. What is a linear regulator?

Linear regulators use transistors or FETs operating in their linear region to subtract excess voltage from the applied input voltage to produce a regulated output voltage. The so-called dropout voltage is the minimum difference between the input voltage and the output voltage required for the regulator to maintain the output voltage within 100mV of its rated value. Positive output voltage LDO (low dropout) regulators usually use power transistors (also called pass devices) as PNP. This transistor allows saturation, so the regulator can have a very low dropout voltage, usually around 200mV; compared to the traditional linear regulators that use NPN composite power transistors, which have a dropout voltage of around 2V. Negative output LDOs use NPN as their pass device and operate similarly to the PNP device of positive output LDOs.

2. What is a switching regulator?

A switching regulator uses an output stage that repeatedly switches between "on" and "off" states, along with energy storage components (capacitors and inductors) to produce an output voltage. Regulation is achieved by adjusting the switching timing based on feedback samples of the output voltage. In fixed frequency regulators, the switching timing is adjusted by adjusting the pulse width of the switching voltage. This is called PWM control. In a gated oscillator or pulse mode regulator, the width and frequency of the switching pulses remain constant, but the "on" or "off" of the output switch is controlled by feedback. Depending on the arrangement of the switches and energy storage components, the output voltage produced can be greater or less than the input voltage, and multiple output voltages can be produced with a single regulator. In most cases, pulse (step-down) switching regulators convert power more efficiently than linear regulators for the same input and output voltage requirements.

2. Advantages and Disadvantages of Linear Regulators and Switching Regulators

1. The main advantages and disadvantages of linear regulators and switching regulators are shown in the following table:

The advantages of linear DC voltage regulators are high stability, small ripple, high reliability, and easy to make into multi-channel output continuously adjustable power supplies. The disadvantages are large size, heavy weight, and relatively low efficiency. There are many types of this type of voltage stabilized power supply. From the output properties, it can be divided into voltage stabilized power supply, current stabilized power supply, and voltage stabilized and current stabilized (bi-stable) power supply that combines voltage and current stabilization. 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 switching regulator directly rectifies to obtain high-voltage DC, and the high-frequency oscillator controls the on-off time ratio of the switch tube to adjust the output voltage. The switching power supply circuit is divided into two types: series type and parallel type. The advantage of the switching voltage regulator is high efficiency, because the transistor itself consumes very little power in the switching state, and can reach 70-80% or even higher efficiency, and does not require a step-down transformer. Its output transformer is much smaller than a 50 Hz power frequency transformer because it works at a high frequency. Therefore, the circuit of the switching power supply is small and light. The switching regulator can work normally in a larger voltage range.

2. The essential difference between linear regulators and switching regulators

The switching regulator is a type of voltage regulator that is different from the linear regulator. Its circuit types mainly include single-ended flyback, single-ended forward, half-bridge, push-pull and full-bridge. The fundamental difference between it and the linear power supply is that the transformer in the circuit does not work at the power frequency but at tens of kilohertz to several megahertz. The power tube 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 voltage regulator is named for this reason.

3. Daily maintenance of linear regulators and switching regulators

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

1. Always check whether the cooling fan and transmission mechanism of the voltage stabilizer are operating normally, and check whether the input voltage and load exceed the rated range. If any abnormality is found, it should be handled in time.

2.Maintain the voltage stabilizer once a month:

1) Carefully clean all parts, especially the carbon brushes and the exposed parts that contact the coils, to remove dirt;

2) Check whether the internal components and wires of the voltage stabilizer are loose. If there is a loose connection or poor contact, it should be handled in time;

3) Replace worn or damaged carbon brushes promptly, and repair or replace faulty or damaged components in a timely manner.

The above is the relevant knowledge about linear regulators and switching regulators that we have classified for you today. I hope it can provide you with reference in the future.