A New Fast Adaptive On-Time Control for Transient Response Improvement in Constant On-Time Control

Bari, Syed Mustafa Khelat; Li, Qiang; Lee, Fred C.

doi:10.1109/tpel.2017.2693382

Cited by 42 publications

(11 citation statements)

References 7 publications

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“…These studies were chosen based on either similar circuit applications or similar design of architecture. Reference [26] and [28] are circuit designed for point of load application, while references [5,20,23,24] and [26] are modified constant on-time circuits designed recently. The remaining studies use a hysteresis-type of architecture design, which is also suitable for fast load transient applications.…”

Section: Resultsmentioning

confidence: 99%

Small signal modelling and stability analysis of internal ramp compensated constant on‐time controller with improved output voltage accuracy for point of load application

Peng

Chen

Petruzzi

et al. 2020

IET Power Electronics

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This paper investigates a constant on-time controller (COT) with internal ramp compensation and improved output voltage accuracy for point of load applications. The pulse width modulation (PWM) output is generated based on internal ramp: by sensing the regulated output voltage and comparing it to an internal reference target, an error signal is generated. This error signal is used to generate a reference for an added ramp signal, which is compared against an error voltage to generate a PWM trigger signal. An adaptive constant on-time scheme ensures a fairly constant switching frequency over a wide range of input and output voltages. This COT control algorithm is able to achieve high accuracy regulation (±0.5% of target) and fast transient response during load step change. A frequency domain small signal model is proposed, and an open loop gain transfer function is developed for this COT control system. The proposed small signal model and design analyses are verified with SIMPLIS simulations and experimental results. wileyonlinelibrary.com/iet-pel IET Power Electron.

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Section: Resultsmentioning

confidence: 99%

Small signal modelling and stability analysis of internal ramp compensated constant on‐time controller with improved output voltage accuracy for point of load application

Peng

Chen

Petruzzi

et al. 2020

IET Power Electronics

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“…In the diagram, the Delay module is implemented after the compensator, with t_on being a fixed value and t_off being a minimal value. Many technologies [8][9][10][11][12][13][14][15] have been proposed to improve the performance of COT under light loads, including various trajectory control technologies [8,13], time-optimized technology [9], various adaptive technologies [10][11][12] and current-mode control technologies [14,15]. In more detail, to follow the natural state trajectory of the system, Li et al [8] proposed a state-trajectory-based control with a single-cycle transient response.…”

Section: Introductionmentioning

confidence: 99%

“…Zhao et al [11] introduced a ripple-based adaptive on-time controlled Buck converter with pseudo triangular ramp compensation. Bari et al [12] solved the issue of the slow transient response caused by the fixed T_on operation that plagued the control of the constant on-time current mode (COTCM) by a new fast adaptive on-time control method. Zhen et al [14] improved the transient response and voltage scaling speed by using current mode variable on-time (CM-VOT) control.…”

Section: Introductionmentioning

confidence: 99%

A Hybrid Constant On-Time Mode for Buck Circuits

Zhong

Shen

2021

Electronics

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To achieve a designed and fixed operating frequency for a controller with high dynamic performance and a high load capacity, a hybrid constant on-time (COT) voltage mode for a Buck circuit is proposed and discussed in this paper. The proposed hybrid strategy is a combination of the classical COT method, a dynamic reference voltage technology and a proportional–differential (PD) module. The workflow is demonstrated in brief, simulations of a Buck circuit with the proposed hybrid COT mode are conducted and comparisons with developed pulse-width modulation (PWM) technology and the hysteresis mode are made. The results show that, with the help of the proposed control scheme, impressive performance from the Buck circuit can be expected. The operating frequency can be fixed well by the hybrid technology without losses of performance and robustness in steady state and will not jump much even with the sudden change of the inputs and the load. The proposed control strategy contributes to the foundation of circuit design and optimization.

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“…To eliminate the effect of delay on the unloading transient performance, an effective scheme is to truncate on-time immediately when load step-down occurs [20]. Based on this idea, some methods are implemented [21][22][23]. In [21], Syed Bari et al proposed a new control strategy based on the current-mode COT control, in which the derivative of the output voltage was used to monitor the load step-down and truncated the on-time.…”

Section: Introductionmentioning

confidence: 99%

A Detection Circuit for Improving the Unloading Transient Performance of the COT Controller

2021

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Fast load transient response and high light-load efficiency are two key features of the constant on-time (COT) control technique that has been widely used in numerous applications, such as for voltage regulators and point-of-load converters. However, when load step-down occurs during an on-time interval, the COT controller cannot respond until the COT interval expires. This delay causes an additional output voltage overshoot, resulting in unloading transient performance limitation. To eliminate the delay and improve the unloading transient response of the COT controller, a load step-down detection circuit is proposed based on capacitor current COT (CC-COT) control. In the detection circuit, the load step-down is monitored by comparing the measured capacitor current with the preset threshold voltage. Once the load step-down is monitored, the on-time is promptly truncated and the switch is turned off. With the proposed detection circuit, the CC-COT-controlled buck converter can monitor the load step-down without any delay and obtain less output voltage overshoot when the load step-down occurs during the on-time interval. PSIM circuit simulations are employed to demonstrate the feasibility of the detection circuit.

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A New Fast Adaptive On-Time Control for Transient Response Improvement in Constant On-Time Control

Cited by 42 publications

References 7 publications

Small signal modelling and stability analysis of internal ramp compensated constant on‐time controller with improved output voltage accuracy for point of load application

Small signal modelling and stability analysis of internal ramp compensated constant on‐time controller with improved output voltage accuracy for point of load application

A Hybrid Constant On-Time Mode for Buck Circuits

A Detection Circuit for Improving the Unloading Transient Performance of the COT Controller

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