1. input voltage range: when the input voltage of the switching power supply changes, the input voltage range that keeps the output characteristics unchanged. The wider the range, the stronger the power supply's ability to adapt to the changes of external mains power, and the wider the operating range of the switching power supply. It is related to the error amplifier inside the switching power supply, the gain of the sampling feedback regulating circuit and the regulating range of the duty cycle. At present, the input voltage range of switching power supply has reached 90v-270v, which can eliminate the 110v/220v transfer switch on many electrical appliances.
2. voltage regulation rate: voltage regulation rate, also known as voltage stability, is the relative change of output voltage when the output current remains unchanged (i.e. the load does not change) and the input AC working voltage changes. This technical index is used to verify whether the stability of the output voltage of the switching power supply meets the required specifications under the harsh power supply voltage environment of Z.
3. current regulation rate: the current regulation rate, also known as load regulation rate, is the relative change of output voltage when the input AC voltage is rated (such as 220VAC) and the output current changes from Z small value 0 to Z large value. This indicator is used to verify whether the output voltage stability of the switching power adapter meets the required specifications under the severe load environment of Z.
4. output internal resistance: the ratio of the change of output voltage to the change of output current. The smaller the ratio, the smaller the change of the power output voltage with the load, and the better the voltage stabilization performance.
5. conversion efficiency: the ratio of power output power to input power. The higher the ratio, the higher the change efficiency. The smaller the size of the switching power supply, the higher the reliability. At present, the efficiency of switching power supply can reach more than 90%.
6. ripple of output voltage: since the voltage stabilization process of switching power supply is a process of continuous sampling and feedback regulation, there will be a superimposed ripple voltage on the output DC voltage, that is, the output ripple voltage. The smaller the value, the better the output characteristics. There are two ways to express ripple: one is the effective value of output ripple voltage; The second is the peak to peak value of output ripple voltage. Generally, the specifications of switching power supply are required to be less than 1% of the output DC voltage, and its bandwidth is 20hz-20mhz or other higher frequencies, such as 100MHz. Under harsh environment, the output instantaneous voltage of switching power supply after its output DC voltage plus noise ripple shall not exceed the output high-low voltage boundary (min value and max value), otherwise it may cause the power supply voltage to exceed or be lower than the working voltage of logic circuit (such as TTL circuit) and malfunction, further causing panic.
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