Introduction to the basic selection criteria of switching power supply
Basic basis for selecting switch mode power supply
Voltage and current range are the two easiest indicators to determine, as long as they are calculated based on the power consumption of the circuit. Testing the extreme values of high and low supply voltages should also be considered.
Most fixed power supplies allow output voltage to vary within a range of ± 10%. If this does not meet the circuit requirements, a power supply with adjustable output or a larger range of variation can be selected.
If this power supply is used to power a combination device, 75% to 90% of the maximum current required by the device is provided by one power supply, and the insufficient part can be connected to two or more power supplies in parallel.
Expansion and Safety of Switching Power Supply
1. Parallel or series operation
When a power source cannot meet the required voltage or current range, two or more power sources (or different outputs of the same power source) can be connected in parallel or series for use. In this working mode, the connection between the voltage regulation and control circuits of each power module still exists, except that one power supply is used as the main control and the other power supply is used as the controlled party.
2. Overload protection
Because a power supply needs to supply different circuits, the current flow of these circuits may be unknown. In order to avoid damage to the power supply, it is necessary to set the range of protection circuits.
Almost all power supplies have the following characteristics: when the output range is exceeded, either the output remains at the maximum output value or the power automatically shuts down. Some programmable power supplies can automatically set the type of stable power output in addition to the output range that can be programmed. That is to say, when the voltage or current required by the external circuit exceeds the set limit, the power supply can automatically switch from a constant voltage source to a constant current source or from a value current source to a constant voltage source.
Adding protective diodes to the power supply can prevent damage caused by misconnection of the polarity of the external power supply. Thermal sensors can also be used to prevent the power supply from burning out due to continuous overload or ineffective cooling.
