Adaptive On-Time Control Buck Converter with a Novel Virtual Inductor Current Circuit

Abstract

This study presents a new virtual inductor current circuit to reduce circuit complexity, which is not necessary to sense inductance current directly. The buck converter was designed to produce an output voltage of 1.0–2.5 V for a 3.0–3.6 V input voltage. The load current range was from 100 mA to 500 mA. It was simulated and verified by SIMPLIS and MathCAD. The simulation results of this buck converter show that the voltage error is within 1%, and the recovery time is smaller than 2 ms for step-up and step-down load transients. Additionally, it achieves less than 26 mV overshoot at full-load step transient response. The circuit topology would be able to fabricate using TSMC 0.35 mm 2P4M CMOS technology. The control mechanism, implementation, and design procedure are presented in this paper.

Design of the Buck Converter without Inductor Current Sensor

“…In contrast to the current contactless sensor, sensor-less solutions are more popular and are proposed in [16][17][18][19][20][21][22][23][24][25][26][27]. In Figure 2, the sensing method is straightforward [16,17].…”

“…Moreover, the constant switching frequency mechanism is not the function of V o . From the methodology perspective, the proposed scheme is different from [22]. This paper proposes another solution for the T ON decision.…”

“…(a) In [22], the TON is decided by the virtual inductor current circuit, which senses the Vin and Vo. Compared with [22], this work eliminates the function of the current sensor. In addition, this work has the feature of the constant switching frequency.…”

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].…”

“…Equation (1) var- T dead is the dead time, T setting is the PWM ON steady-state arrival time, and T adc is the ADC operation time. A limitation is that the time taken to detect the current in the single-shunt resistor inverter should be longer than the T min defined in Equation (1). If the T min is not secured, it is impossible to detect the current with the shunt resistor.…”