A high performance adaptive on-time controlled valley-current-mode DC–DC buck converter

Abstract

This paper presents an AOT-controlled (adaptive-on-time, AOT) valley-current-mode buck converter for portable application. The buck converter with synchronous rectifier not only uses valley-current-mode control but also possesses hybrid-mode control functions at the same time. Due to the presence of the zero-current detection circuit, the converter can switch freely between the two operating modes without the need for an external mode selection circuit, which further reduces the design difficulty and chip area. The converter for the application of high power efficiency and wide current range is used to generate the voltage of 0.6–3.0 V with a battery source of 3.3–5.0 V, while the load current range is 0.05–2 A. The circuit can work in continuous conduction mode with constant frequency in high load current range. In addition, a stable output voltage can be obtained with small voltage ripple. In pace with the load current decreases to a critical value, the converter transforms into the discontinuous conduction mode smoothly. As the switching period increases, the switching loss decreases, which can significantly improve the conversion efficiency. The proposed AOT controlled valley current mode buck converter is integrated with standard 0.18 μm process and the simulation results show that the converter provides well-loaded regulations with power efficiency over 95%. When the circuit switches between the two conduction modes drastically, the response time can be controlled within 30 μs. The undershoot voltage is controlled within 25 mV under a large current hopping range.

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

“…So, the BJT emitter input and collector output are used to sensitively amplify the error between the ZCD_SW and ZCD_REF. The switching speed of these zero current detection comparators mainly depends on the delay of the amplifiers and the inverter [31].…”

Design of the Buck Converter without Inductor Current Sensor

“…(A) Compared with [33], the proposed scheme can provide better recovery time. (B) In [24,33], the output voltage is a fixed value.…”

“…(A) Compared with [33], the proposed scheme can provide better recovery time. (B) In [24,33], the output voltage is a fixed value. However, this work can provide greater flexibility for the output.…”

A Precise Current Detection Method Using a Single Shunt and FET Rds(on) of a Low-Voltage Three-Phase Inverter

“…Among many technologies, research on current measurement is receiving a lot of attention. According to a recent study, a virtual inductor circuit is proposed to reduce the circuit complexity in sensing inductance current [1] or a method of adaptively changing the transient response and voltage scaling rate with time by limiting the time of the switch to the equivalent duty cycle due to the minimum off-time and fixed on-time, [2] the use of a hysteresis current control buck converter using constant frequency and active current sensing technology [3], and the valley current mode using adaptive on time(AOT) [4].…”