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How to use adjustable switching power supply

Switching power supplies are known for their efficiency. Adjustable voltage/current power supplies are an interesting tool that can be used in many applications, such as Li-ion/battery chargers or power supplies.

The reason for building this switching power supply requires an adjustable benchtop power supply. A linear topology would not work for this power (2400W = 2.4 kW!), so a switching topology of two forward switches (half-controlled bridge) was chosen. Switching power supplies use IGBT transistors and are controlled by a chip. The supply voltage first passes through the EMI filter. It is then rectified with a bridge rectifier and smoothed with a capacitor. Due to the high capacity, there is a surge limiting circuit with relay contacts and R2 resistor. The relay coil and fan (via AT/ATX PC power supply) are powered from 12V, while resistor R1 is used to depressurize it from the 17V power supply. Choose the R1 value so that the voltage on the relay coil and fan is 12V. The power circuit uses TNY267. It is similar to the power supply described here. R27 provides undervoltage protection of the power supply - it will not turn on below 230V DC. The output frequency of the control circuit is 50kHz and the duty cycle is 47 percent. It is powered through a Zener diode, which reduces the supply voltage to 5.6 V (ie, drops it to 11.4 V) and shifts the UVLO threshold from 7.9 V (low) and 8.5 V (high) to 13.5 V and 14.1 V. The chip then starts working at 14.1 V and never goes below 13.5 V, protecting the IGBT transistors from saturation.

This is the operation of adjustable switching power supply, what do you think? Welcome to talk about how to use the operation of adjustable switching power supply.

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