A Fast Transient Adaptive On-Time Controlled BUCK Converter with Dual Modulation

Area of Science:

• Electrical Engineering
• Power Electronics
• Integrated Circuits

Background:

• Buck converters are essential for voltage regulation.
• Achieving fast transient response and high light-load efficiency in buck converters remains challenging.
• Adaptive on-time (AOT) control offers potential for improved performance.

Purpose of the Study:

• To propose a fully integrated adaptive on-time controlled buck converter.
• To enhance light-load efficiency by enabling adaptive mode switching.
• To achieve fast load transient response.

Main Methods:

• Implemented an adaptive on-time generator for stable output frequency.
• Integrated a zero current detection circuit for adaptive pulse width modulation (PWM) and pulse skip modulation (PSM) switching.
• Designed and fabricated the buck converter using TSMC 0.18 µm BCD process.

Main Results:

• The converter operates with input voltages from 5.5 to 15 V and output loads up to 5 A.
• Achieved transient recovery times of 13 µs (light-to-heavy) and 15 µs (heavy-to-light).
• Demonstrated minimal voltage overshoot (57 mV) and undershoot (53 mV).

Conclusions:

• The proposed dual modulation AOT controlled buck converter effectively balances efficiency and transient response.
• Adaptive switching between PWM and PSM enhances performance under varying load conditions.
• The design is suitable for applications requiring efficient and responsive power conversion.