How to choose the IC of the switching power supply and the role of the switching power supply IC

Power supply IC refers to the pulse width control integration of switching power supply, and the power supply relies on it to adjust the stability of output voltage and current.

Switching power supply is a kind of voltage conversion circuit, the main working content is to boost and buck, widely used in modern electronic products. Because the switching transistor always works on.

On" and "Off".

state, so it is called a switching power supply. The switching power supply is essentially an oscillation circuit, and this way of converting electrical energy is not only used in the power supply circuit, but also in other circuit applications, such as the backlight circuit of the liquid crystal display, fluorescent lamp, etc. Compared with transformers, switching power supplies have high efficiency, good stability and small size.

The advantages of switching power supply simplification diagram, the disadvantage is that the power is relatively small, and it will produce high-frequency interference to the circuit, the circuit is complex and not easy to maintain, etc. Compared with switching power supplies and linear power supplies, the cost of both increases with the increase of output power, but the growth rate of both is different.

One way to reduce the power supply current for running applications is to cut off power to unnecessary circuits depending on the operating state. By plugging in the power switch IC, it can be easily turned on and off, and even the power cord can be protected. Power switch ICs do not have the voltage control capabilities of LDO regulators or DC DC converters, but they are more efficient from a voltage drop and power loss perspective when flowing high currents.

In addition, the power switch IC is equipped with protection against overcurrent and overtemperature, which is a function that FETs do not have as switches. Therefore, it is possible to construct a multifunctional protection circuit with a small installation area using a power switch IC.

To put it simply, the power switch IC is a kind of semiconductor component, which is used for stuffing ears that Wang regrets can easily open and turn off the power supply, and even the power cord can be protected by Maolingbu, and some power switch ICs are also equipped with protection functions such as overcurrent and overtemperature.

Clause. 1. Select the safety and electromagnetic compatibility certifications that need to be complied with.

Clause. 2. Select the standard power supply of the electric cover volt source adapter manufacturer, including the standard size and output voltage.

Clause. 3. Select the functions of each grinding item according to the needs of the application

1. Protection function: over-voltage protection, over-temperature protection, over-load protection, etc.

2. Application function: signal function, remote control function, telemetry function, parallel function, etc.

3. Special functions: power correction, uninterruptible power, etc.

Clause. Fourth, consider the load characteristics.

Clause. 5. Considering the working environment temperature of the power supply, whether there is additional auxiliary heat dissipation equipment, the output of the power supply needs to be reduced when the ambient temperature is too high.

Clause. 6. Select the appropriate input voltage range for the IOT. Taking AC input as an example, the commonly used input voltage specifications are 110 volts and 220 volts.

Clause. 7. Choose the right power. A switching power supply consumes a part of the power when it is working and releases it in the form of heat.

In terms of input anti-interference performance, due to the characteristics of its own circuit structure (multi-stage series), the general input interference such as surge voltage is difficult to pass, and it has a great advantage compared with the linear power supply in the technical index of output voltage stability, and its output voltage stability can reach (. As a kind of power electronic integrated device, the switching power supply module should pay attention to the following points in the selection:

Power supply. The option of infusion and burial of the creeping current.

Due to the high efficiency of the switching power supply, it can generally reach more than 80%, so in the selection of its output current, the maximum absorbed current of the electrical equipment should be accurately measured or calculated, so that the selected switching power supply has a high performance ratio, and the output calculation formula is usually as follows:

is=kif

Where: is - the rated output current of the switching power supply;

if—the maximum absorbed current of the electrical equipment;

k—margin coefficient, generally taken;

Earthing. Switching power supply will produce more interference than linear power supply, electrical equipment sensitive to common mode interference, grounding and shielding measures should be taken, according to the same EMC limit, the shape of the switching power supply are taken EMC EMC measures, so the liquid friend switching power supply should generally be equipped with EMC electromagnetic compatibility filter. For example, the HA series switching power supply of LeadHuafu Technology can meet the above requirements of electromagnetic compatibility by connecting its FG terminal to the ground or connecting to the user's chassis.

Protection circuits. The switching power supply must have protection functions such as overcurrent, overheat, and short circuit in the design, so the switching power supply module with complete protection functions should be preferred in the design, and the technical parameters of the protection circuit should be matched with the working characteristics of the slag of the electrical equipment, so as to avoid damage to the electrical equipment or the switching power supply.