Generally, electrical equipment is debugged before it is used, so that problems can be found in time and measures can be taken to solve them. The switching power supply will also be debugged, so what problems will be encountered in the process of debugging the switching power supply? And how to solve it?
1.No-load and light load cannot be started
In the case of no load and light load, the supply voltage (VCC) of the circuit will jump back and forth between the starting voltage and the shutdown voltage because the induced voltage of the windings is too low to start. This phenomenon can be solved by increasing the number of VCC winding turns, decreasing the VCC current limiting resistance, and adding a false load appropriately.
2.The short-circuit power is too high
When the output of the switching power supply is short-circuited, there are many repetitive pulses, and the current peak value of the switching tube is very large, so the input power of the switching power supply increases, and the VDS is too high. Therefore, it is necessary to reduce the number of current pulses and reduce the peak current.
3.The IC temperature is too high
The reasons for the high temperature of the switching power supply IC may be: too much internal MOSFET loss, poor heat dissipation, and too high temperature of the working environment. Too high a temperature not only affects the efficiency of the switching power supply, but also may shorten the life span. IC temperature is too high can be solved by:
a.Increase the distance of the transformer windings to reduce the interlayer capacitance;
b.The working environment should be ventilated and smooth, and the IC should be based on the principle of parts with high ambient temperature;
c.A large part of the heat of the IC is directed to the PCB and the copper foil on it, so try to increase the area of the copper foil and apply more solder.
4.The transformer is saturated
The reason for the saturation of the transformer may be that the transformer inductance is too large, the number of turns is too small, there is no soft start, the saturation current point of the transformer is smaller than the maximum current limit point of the IC, etc. Transformer saturation can lead to unstable switching power supply output, increased noise, and reduced efficiency. Therefore, when the transformer is saturated, it is necessary to take measures in time, which can be solved by reducing the current limiting point of the IC, strengthening the soft start, and making the current envelope through the transformer rise more slowly.
The above are some of the problems and solutions commonly encountered in the process of switching power supply debugging.