Design Of A Low Power And Wide Input Range Monolithic LDO

The rapid development of electronic technology makes widespread popularity of portable electronic devices. And the corresponding power management technology has also been an unprecedented development. As one important kind of power management products, LDO has been widely used for its advantages such as low voltage, low output noise, low output ripple, small size and simple application circuit. So, LDO has a promising future especially in low-power, low-noise, high-precision and low-cost applications.This paper presents a low power and wide input voltage range monolithic LDO. The no-load quiescent current is only 2.12μA and the input voltage range is 3.4V to 24 V in full load range. The output voltage is fixed at 2.5V and the maximum output current is up to 80 m A. Moreover, the LDO keeps stable when there is no external capacitor. In addition, the chip uses constant current limit in combination with foldback current limit for the chip overcurrent protection. The bandgap operational amplifier(the bandgap reference and error amplifier are integrated together) circuit and foldback current limit circuit are the main features of the LDO. The chip provides good power solution for ultra-low power microcontrollers and handheld electronic devices. The proposed LDO has no separate voltage reference, but voltage reference is an important module in the vast majority of LDOs. So, it is necessary for the design of the voltage reference. And in order to accommodate no-resistor design trends at the same time, this paper designs a continuous output and fully integrated switch capacitor voltage reference circuit which is suitable for resistorless LDO and So C. This is a sub-bandgap reference which achieves a temperature coefficient of 15.4ppm/℃ from-20℃ to 80℃ and has an output voltage of 323 m V.This paper firstly illustrates the application background of LDO. And then introduces its basic principles. And next, the main performance indicators and the system architecture as well as some key design considerations are described. After that, the specific circuits and relevant simulation results are given. Finally, a totally on chip switch capacitor voltage reference circuit with continuous output and without resistor is proposed.The designed circuits are simulated in 0.35μm BCD process by using Hspice sofeware. The simulation results show that the LDO achieves the desired design specifications, and the proposed switch capacitor voltage reference circuit also has a good performance.