Main electrical performance specifications of the power adapter

When purchasing a power adapter, we must have some standards and indicators that can be referenced. Next, the power adapter manufacturer explains the main electrical performance parameters of the power adapter in detail.

1. Input voltage range: When the input voltage of the switching power adapter changes, the input voltage range keeps the output characteristics unchanged. The wider the range is, the stronger the power adapter is to adapt to the external changes in the mains, the wider the working range of the switching power supply. It is related to the error amplifier inside the power adapter, the gain of the sampling feedback regulating circuit and the range of duty ratio regulation. At present, the input voltage range of switching power supply has been 90V-270V, which can save the 110V/220V switch on many electrical appliances.

2. Voltage adjustment rate: Voltage adjustment rate, also known as voltage stability, is the relative change of the output voltage when the output current does not change (that is, the load does not change) and the input AC operating voltage changes. This technical index is used to verify whether the stability of the output voltage of the switching power supply meets the requirements under the most severe voltage environment.

3. Current adjustment rate: Current adjustment rate, also known as load adjustment rate, is the relative change in the output voltage when the input AC voltage is rated (such as 220VAC) and the output current changes from the minimum value of 0 to the maximum value. This index is used to verify that the output voltage stability of the switching power adapter meets the requirements under the most severe load environment.

4. Output internal resistance: the ratio of the change in output voltage to the change in output current. The smaller this ratio is, the smaller the change of the output voltage of the power supply with the load size, and the better the voltage stability performance.

5. Conversion efficiency: the ratio of output power to input power. The higher the ratio, the higher the change efficiency, the smaller the volume of the switching power supply, and the higher the reliability. At present, the efficiency of switching power supply can reach more than 90%.

6. Ripple of output voltage: Because the voltage regulation process of switching power supply is a process of continuous sampling feedback regulation, there will be a superimposed ripple voltage of DC output voltage, that is, the ripple voltage of output. The smaller the value, the better the output features. There are two ways to express ripple: one is the effective value of the output ripple voltage; The second is the peak-to-peak value of the output ripple voltage. Generally, the specifications of the switching power supply must be less than 1% of the output DC voltage, and the bandwidth must be 20Hz-20 MHZ or a higher frequency, such as 100MHz. When the switching power supply is in a bad environment, its output DC voltage and the output instantaneous voltage after noise ripple should not exceed the output high and low voltage boundary (Min value and Max value). Otherwise, the power supply voltage may exceed or be lower than the working voltage of the logic circuit (such as TTL circuit) and misoperate, which further causes the shutdown phenomenon.

7. Output voltage accuracy: The output voltage varies with the power consumption of the load equipment. The smaller the change, the better. It is mainly related to the gain and frequency response characteristics of the feedback regulating loop. The higher the gain of the feedback regulating loop, the more stable the reference voltage and the better the stability of the output voltage.

8. Output power: the power supply can output the maximum energy to the load, the greater the power, the power load of the device can be more, the output power is equal to the output voltage value multiplied by the circuit value. To ensure the safety of the power adapter and meet the consumption of the device, the output power must have a certain margin, generally 20%-50%.