Special power supply manufacturers analyze how power modules can improve the load effect

Special power supply manufacturerThe analytical load effect is the percentage of the difference between the output voltage under no load or light load and the full load output voltage to the full load output voltage, which represents the influence of load changes on the output voltage of the power supply. So how can the power module improve the load effect?

(1) Correctly use the remote sensing end of the power module

Many low-voltage and high-current output module power supplies have remote sensing terminals (+S, -S ). The remote sensing terminal allows the internal feedback control circuit of the module power supply to be connected to the load through the detection line, thereby compensating for the influence of the large current line voltage drop on the load effect value. The detection line is separated from the output high-current load line, and the remote sensing terminal directly detects the voltage at both ends of the load. If there is a 0.5V voltage drop on the high-current load line, through the remote sensing terminal, the internal feedback control circuit of the module power supply will increase the output voltage by 0.5V to compensate for the line voltage drop to ensure that the load voltage is at the rated value. Generally, the module power supply can compensate about 1.0V for the voltage drop of the load line. This method is to increase the output voltage of the module power supply to maintain the voltage value at both ends of the load. The connection between the remote sensing terminal and the load should be shielded as much as possible to prevent electromagnetic interference from affecting the feedback control circuit inside the module power supply. Inside the module power supply, there is usually a resistor between the remote sensing terminal and the output terminal of the module power supply. If the remote sensing terminal is not connected to the load terminal due to carelessness, this resistor can prevent the output terminal voltage from rising too high. If the remote sensing terminal is not used, it should be short-circuited with the positive and negative terminals of the power supply. At this time, the module power supply works in the local detection mode.

(2) Capacitive load capacity

Capacitive load capacity: As a means of power decoupling and anti-interference, capacitors are indispensable in modern electronic circuits. However, considering the comprehensive protection capabilities of the power supply and output short-circuit protection, the capacitive load capacity should not be too large, otherwise the protection characteristics will change. Difference. Therefore, the total load capacitance must not exceed the larger capacitive load capacity during use.

(3) Minimize wire resistance and contact resistance

To reduce wire resistance and contact resistance, it is simple to understand that less contact will reduce the impact of the low load effect, just as the air resistance contact area is small and the natural speed is faster. This is the same principle.

The special power supply manufacturer reminds you to pay attention to the contact resistance between the output terminal of the module power supply and the load, especially when the current is large. Like the above-mentioned excessively long load wires, these connections may have a contact resistance of a few millivolts to several tens of millivolts and a load effect variation of several percent. A low-voltage 5V output, if there is a 5mV change from no load to full load, the load effect is 0.1%. Obviously, the high-current connection contacts should be properly handled and welded. The solution to this problem is: spade lugs, plugs, etc. must be carefully derusted. The PCB output terminal inside the module power supply should provide several parallel contacts for high-current loads and ensure that it is clean.