Principles of design and distinctive characteristics of an integrated switching power supply
Compared with the traditional switching power supply, the special integrated switching power supply has the characteristics of novel circuit, unique function, advanced performance and wide application fields. The common special integrated switching power supply is usually designed by using a single-chip switching power supply integrated circuit, coupled with the corresponding peripheral circuit (including control loop), has different output characteristics and application fields, and can meet the needs of different users.
Classification of special integrated switching power supply
Special integrated switching power supply mainly includes the following 5 types:
1) Composite switching power supply;
2) Constant voltage/constant current (CV/CC) switching power supply;
3) Cut-off output switching power supply;
4) Constant power output switching power supply;
5) Other special switching power supplies, such as high-speed modem (HighSpeedModem) power supply, DVD power supply, etc.
Design scheme and characteristics of special integrated switching power supply
There are two design schemes for special single-chip switching power supply: the first is to use general-purpose single-chip switching power supply integrated circuits (such as TOPSwitch-II, TOPSwitch-FX, TOPSwitch-GX and other series), and then add voltage control loop, current control loop It is characterized by large output power, but the peripheral circuit is complex; the second is to use the recently released LinkSwitch series of high-efficiency constant voltage/constant current three-terminal single-chip switching power supply chips, or use LinkSwitch -TN series, DpA-Switch series monolithic switching power supply dedicated IC, which can greatly simplify the circuit and reduce costs, suitable for the construction of special switching power supplies with medium and small power.
Performance characteristics of special integrated switching power supply
1) Using 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 <5μA, the rated output voltage is 5.5V, and the maximum output current is 0.45A, 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, the output voltage is allowed to have ±10% error when the primary.
5) It has the functions of overheat protection, output short circuit protection and open loop protection.
6) Comply with the international standard of electromagnetic compatibility CISpR22B/EN55022B.
