Design Of AC-DC Linear Regulator Based On BCD Technology

With the improvement of people's living standard, intelligent home appliance has become a new favorite. The trend of the intelligent home appliance is rising. In the intelligent home system, the power supply system is just like a heart to human has play an important role, it is the guarantee of normal operation of various control systems. In traditional design scheme of the control system, the RC power supply and the switch power supply were taken. The RC power supply has features of low cost and small in size of the power supply, and it accord with the requirement of intelligent household for power supply. But it also exists some shortcoming of low conversion efficiency, small output voltage fluctuation range, debugging relatively complex, easy to get an electric shock and so on. The switch power supply often employs an isolated AC-DC buck, with a wide input voltage range, high efficiency and perfect protection function, and low standby power consumption, but the relatively large volume, high cost disadvantage.Considering shortcoming of the traditional scheme, this paper designed a model of AC-DC linear regulator that applied to intelligent home appliances power supply system with 0.8um BCD process. Its power supply design has the advantages of both traditional design faults, with wide input voltage range, less peripheral devices, circuit has simple structure, small volume, simple debugging and circuit protection function is perfect, low standby power consumption, low cost advantages, but its efficiency is low. Chip's design are divided into two parts of circuit design and layout design.The Circuit is mainly completed with the following work: firstly, the chip was divided into several function module of startup circuit and internal power supply circuit, band gap voltage reference circuit, bias circuit, linear regulator circuit, protection circuit and control logic circuit. And the circuit was set up according to the principle of the realization of each functional module structures, then the parameters of device is set through the theoretical calculation, after that Hspice simulation tool was used for the transient, dc and ac three aspects of the all corner process simulation, at the same time, the parameter was justice to make it meet the design requirements. Secondly, a complete circuit of the new chip was integrated by the module circuit designed, after finishing the integrated chip system simulation, function module circuit parameters was further adjustment according to the simulation results, and make integral circuit to meet the design requirements. At last, the circuit of chip was finished.The layout is mainly completed with the following work: firstly, the chip layout was partition according to the function of each module, and the function modules' layout were designed in sequence, then each of them passed the DRC and LVS check. Secondly, the layout of the function modules was assembled, and it passed the DRC and LVS check again. Finally, extracting the parasitic parameters and carrying on the system simulation, and to fine-tune chip circuit and layout according to the simulation results, after that to complete the layout design work flow and taped out.The design of chip circuit achieve the desired design requirements. the circuit Simulation shows that can output a 5V dc voltage of high precision under the condition of 90V~265V ac input. When the load current 50 m A, PSRR reaches 60 d B, its higher than the design requirements about 35 m A/60 d B. Also it achieved the design targets of having the maximum load capacity of 100 m A, load regulation of 0.2 V/A, linear regulation of 7.79 m V/V, temperature changes in-40?~150? temperature drift of output voltage of 12.8 ppm/?. On the side the chip has some safe function such as OTP, UVP and UVLO and so on, At the same time it reserve the function of output voltage adjustment, only need to change a few wires, the output voltage can be changed.