Introduction to the design scheme and characteristics of special integrated switching power supply
Compared with traditional switching power supplies, special integrated switching power supplies have the characteristics of novel circuits, unique functions, advanced performance, and a wide range of application fields. Common special integrated switch power supplies are usually designed using single-chip switch power supply integrated circuits, coupled with corresponding peripheral circuits (including control loops), with different output characteristics and application fields, which can meet the needs of different users.
Special integrated switch power supplies mainly include the following five types:
1) Composite switching power supply;
2) Constant Voltage/Constant Current (CV/CC) Switching Power Supply;
3) Cut off output type switching power supply;
4) Constant power output switching power supply;
5) Other specialized switch power supplies, such as High Speed modem power supplies, DVD power supplies, etc.
Design Scheme and Characteristics of Special Integrated Switching Power Supply
There are two design schemes for special single-chip switching power supplies: the first is to use general-purpose single-chip switching power supply integrated circuits (such as TOpSwitch II, TOpSwitch FX, TOpSwitch GX series, etc.), and then design them with peripheral circuits such as voltage control loop and current control loop. Its characteristic is that the output power is large, but the peripheral circuits are complex; The second method is to use the recently released LinkSwitch series high-efficiency constant voltage/constant current three terminal single-chip switching power supply chips, or to choose LinkSwitch-TN series, DpA Switch series single-chip switching power supply dedicated ICs, which can greatly simplify the circuit, reduce costs, and are suitable for constructing medium and small power special switching power supplies.
Performance characteristics of special integrated switching power supply
1) Adopting high-efficiency constant voltage/constant current single-chip switching power supply LNK500, the AC input voltage range is 85-265V. When the AC input voltage is 265V, the leakage current is less than 5 μ A, the rated output voltage is 5.5V, the maximum output current is 0.45A, and the output power is 2.5W.
2) Low power consumption, high efficiency, no-load power consumption<0.3W, typical value of power efficiency η≈ 68%.
3) At the peak power point, an error of ± 10% is allowed in the output voltage when it is primary.
5) It has overheat protection, output short circuit protection, and open-loop protection functions.
6) Compliant with the international standards CISpR22B/EN55022B for electromagnetic compatibility.
