Research On The Key Techniques Of Power Management IC With Analog And Digital Control

In recent years, the rapid development of semiconductor technology leads to dramatic grows of the integrated circuit (IC), such as integrated power management systems. Traditionally, analog control is always used in power management IC. Meanwhile, digital control, which is a thriving control, is bringing more advantages, including insensitivity to parameter variation, programmability and even fewer external components, and is widly used in power management ICs. In this paper both the analog control and digital control will be studied and some of the key issues will be more focused, including the design of low power bootstrap driver which is used in high voltage buck converter, the design perspective and modling of digital controlled power converter, the design of a multimode digital controller IC for flyback converter with high accuracy primary side feedback, and the research of adjustable and high accuracy primay side sensing technology.In this paper, an analog control strategy of a high voltage buck converter is proposed first. The high side power switch is integreate into the controller IC in this converter, so as to reduce the size and cost. Meanwhile, NMOS is adopted to minimize the area of the IC. Also the conduction loss could be lower. A lower power bootstrap driver is designed to drive this NMOS. Compared with tradional driver, this driver consumes less power and could boost the driving voltage as high as possible. At the same time, PWM/PSM double modes control and adjustable slope compensation are introduced in the controller, so that the efficiency and performance of the converter can be improved.Then the digital control of power management IC is studied. In recent years, digital control is attacting more and more attention. And a power management with digital control is called digital power. Digital power is bring more adnvantages, such as high stability, high integration and strung expandability. The design strategies of the digital power are discussed in this paper, including analog-to-digital converter, digital compensator and digital pulse width modulator. Besides, the quantization and limit cycle of the digital power are also analyzed. In this article, a digital power converter is proposed with the simulink.And then, a multimode digital controller IC for flyback converter with high accuracy primary side feedback is proposed. With the high accuracy primary side feedback and the internal digital compensator, the flayback can output constant voltage (CV) or constant current (CC) depending on the load current. In order to improve the efficiency, PFM control is adopted during light load while PWM is used during normal load in CV mode. And in CC mode, quasi-resonant control is adopted. The controller IC has been taped-out, and the test results show that the chip works well.Finally, the technology of primary side sensing is studied in a deep-going way. And an adjustable primary side sensing techonology is proposed, whose accuracy is independent to the device parameters.