The Front-end Design Of Power Supply Management IC For Dual Channel USB Equipment

Since puting out in 1995, USB(Universal Serial Bus) has become the main interface of external communication to the computer in short order. With the issue of serial bus criterion about USB 2.0, increasing kinds of USB peripheral equipment present themselves in our everyday life.Especially, the communicatory equipment between the USB and computer emerges in an endless stream. In respect that USB communicates with the computer by four cables, among which there are power and ground wire, it is possible to supply power for the peripheral equipment by USB interface. However, the USB equipment may be damaged because of the operating misplay, the question of too high voltage or current, and so on. So it is essential to design a kind of power supply management chip for the USB apparatus.Based on CMOS technology and using the tools of Cadence IC5.0 and SpectreS, a type of single-chip power supply management IC is designed for the USB of Dual Channels. It restrains the in-rush currents during hot-plug events. This product has two channels which work separately. To protect the USB equipment, one of the channels turns off when it is Over Temperature, over current or under voltage, the other one still works. The range of the normal temperature is 0-75°C. OSC Circuit's working frequency is fixed at 100 kHz. The output voltage is 5.0V and output current is 500mA. In sum, the favorable performance ensures the single-chip IC can be mainly used in the USB equipment.In this paper, the total structure of the IC is present firstly according to the function requirement. Then the all basic-circuits are also designed and simulated carefully including active resister, current mirrors, comparator, inverter, AND gate, OR gate. In the meantime, to gain the final ends, sub-circuits are amply designed and simulated including bias circuit, voltage reference circuit, enable circuit, circuit of oscillator generator, charge-pump circuit, under voltage lockout, over temperature protect circuit, over current protect circuit, output circuit, error flag circuit.At last, the synthetic circuit is simulated about power-up and down working, the controlling of enable signal, over current working, over temperature working. The results of simulation meet the function requirement. So the front-end design is finished completely.