Vishay constant on-time (COT) converters combine high-efficiency regulation with extremely small transient response time and simple designs. The COT converters can also be configured in a buck-boost topology, allowing for a negative output voltage. This application note looks at the SiP12116 configured as a negative output buck converter.
The buck topology is conventionally used to convert a larger bus or system voltage into a smaller voltage. The advantage of using a buck converter is that efficiency is very high when compared to a linear regulator performing the same conversion.
In order to generate a negative output voltage from a positive input voltage, the designer would usually opt for the buck-boost topology or possibly a SEPIC converter, both of which offer reasonable efficiency that is much higher than a linear regulator. However, the same outcome can be reached with a buck converter. With a slight alteration to the nodal references of a synchronous buck converter, we can create a negative boost converter.