Start-up Circuit and Power Sequence Design for Initial Start-up of Hysteretic Controlled Step-down Converter- Chai-won Kim-Department of Electronics & Electrical Engineering Graduate School Dankook University-2018

Initial Start-up of Hysteretic Controlled Step-down Converter Chai-won Kim Department of Electronics & Electrical Engineering Graduate School Dankook University

ABSTRACT

 With the rapid spread of battery-based portable products that emphasize convenience like Smart-phones today, the importance and demand for power management circuits are rapidly increasing. Therefore, miniaturization, long operation time, and stability are important for electronic devices, so the power management circuit needs to research and develop low power, miniaturization and light weight in accordance with market demand. Since the power management circuit plays a role of the other system, stable operation is important. In this paper, we design a dual soft-start circuit and a power-up sequence for stable start-up because the entire system starts to run faster as the power management circuit becomes faster. Digital Soft-start has low power consumption and can easily change the reference voltage. In addition, in the case of the digital soft-start circuit, there is an advantage that an external capacitor element is not necessary and the area can be reduced. In the case of the analog type soft-start circuit, the soft-start time can be adjusted by adjusting the external capacitor value according to the user, and the output voltage is linear. Therefore, in this paper, dual soft-start circuit is designed to support both the advantages of digital and analog soft-start. In the case of the power-up sequence design, after the supply voltage of the buck converter is supplied, the required voltage between the internal circuits of the Bias Block is monitored for a stable bias voltage. If the voltage required by one circuit is secured, the next bias circuit starts to operate Respectively. As a result, the power-up sequence is designed in order of Bandgap Reference-> Enable-> LDO-> UVLO-> Mode-> Soft-start so that stable operation can be performed during start-up of the buck converter. As a further study, we proposed a soft-start circuit design method to reduce the start-up time of Buck converter. This design was designed using Samsung BCD 0.13um process, and Psim provided by Korea Power Systems Co. and Cadence provided by Cadence Co. were used. We used the Virtuoso layout editor for layout design and Mentor's caliber for DRC and LVS verification.

LINK
https://www.mediafire.com/file/xuwxxukj7fbcgv5/Hysteretic_Controlled_Step-down_Converter.pdf/file