A Stability Condition for Constant-On Time Buck Converters Suitable for Automotive Applications

Approximate stability boundaries for Constant on- Time buck converters are derived and verified against numerical results obtained by bifurcation analysis. These boundaries are given as analytical expressions involving the main Constant on- Time (cot) buck converter parameters. They allow the designer to avoid the appearance of the pulse bursting phenomenon. A case study is proposed having in mind automotive applications, which are characterized by a wide input-voltage range. The input- voltage and the output-capacitor equivalent series resistance, that is typically poorly controlled for many types of capacitors, were chosen as bifurcation parameters.