An Efficient Power Supply Chip Design With Fault Self-protecting Functions Integrated

With the fast development of science and technology, especially the great progressof electronics, portable mobile devices, such as phones and tablets become an importantpart in people’s lives. Switching power supply, known as the heart of all electronicproducts, becomes the focus of many universities and companies’ research. Increasinglysevere international energy crisis requires higher efficiency of power supply. In addition,mobile devices are often used in complex conditions, which requires switching powersupply with high reliability. Therefore,high-efficiency, high reliability switching powersupply chips become the popular research directions in the field of power.This issue has designed a high-efficiency switching power supply with automaticfault handling function integrated. The chip integrates a700V high-voltage powertransistor, oscillator, duty cycle modulating circuit as well as a variety of protectioncircuits. The chip can work in different modes depending on different loads. As the loaddecreases, the chip work from high frequency, changing frequency and low frequency topulse skipping mode, so that the power supply has a very high efficiency in the entireload range. Besides, the chip integrates a variety of protection blocks, such as inputovervoltage protection, input undervoltage protection, output overvoltage and thermalshutdown protection. So, the chip has a high reliability in different conditions.The paper firstly introduces the basic theory and control mode of differentswitching power supply topologies. And then, it gives an overall diagram of the chip,describes the functions of each module and pin, and gives out how the chip works. Nextpart, the module circuits design, is the focus of this article. In this part, we mainlyintroduce the following modules: high order compensated low temperature coefficientvoltage reference and current reference (exponential curvature compensation for voltagereference and piecewise linear compensation for current reference); Internal overvoltageand undervoltage module, including high voltage current source, overvoltage andundervoltage comparators and the error amplifier; auto-restart module: on one hand,when the feedback loop breaks, the chip begins to auto-restart to reduce the chip’s lossin fault condition and improve its efficiency, on the other hand auto-restart module can take different actions depending on different line voltage failures(such as undervoltage,overvoltage and latch overvoltage, etc.), to protect the chip and power supply fromdamage. Finally, the issue gives a typical application circuit of the chip. In this part, wegive out a loop stability analysis and the all-chip functional simulation with Hspice.