Single-inductor Multiple-output DC-DC Converter Research Articles

An efficient controller design of a PV integrated single inductor multiple output DC-DC converter for dynamic voltage and low power applications.

In this article, a Single Inductor Multiple Output (SIMO) DC-DC boost converter for driving independent three outputs of dynamic voltage and low power is proposed. Compared with the traditional SIMO DC-DC converter, the proposed work accomplishes (i) independent control of power at each output, (ii) small switch count, (iii) relatively better scalability with increasing output channel, (iv) fast response time, and (v) relatively better efficiency. The core aim of the current article is to implement an efficient controller design of the SIMO DC converter circuit operating in continuous conduction mode for dynamic voltage applications. The SIMO circuit comprises a photovoltaic (PV) array as a renewable energy harvesting source at the input. A hysteretic controller based on direct control with seamless transition control topology is implemented in this model for SIMO operation. This scheme is popular due to its less cost, simple, easy-to-use design architecture, and fast speed of close loop control. The configuration of the solar array is designed to deliver maximum power on the input of the SIMO DC-DC converter. For tracking the maximum power point, incremental conductance with integral control configuration is applied on the PV array with fast speed and efficiency. The MATLAB/Simulink environment is utilized for model configuration. The simulation results show that the proposed SIMO configuration with the PV array provided 100.5 W and 21.7 W for 1000 W/m2 and 250 W/m2, respectively.

SIMO DC-DC Converter with Low-Complexity Hybrid Comparator-Charge Control

A hybrid control method using a comparator and a charge control method is proposed for a single-inductor multiple-output (SIMO) DC-DC converter. SIMO DC-DC converters have the weaknesses relating to cross-regulation, as all the output channels share the energy stored in a single inductor. Although multiple control methods such as Time-Multiplexing Control (TMC) and Ordered Power Distributing Control (OPDC) have been proposed to prevent cross-regulation or to improve load capability, effective use of limited resources appears to have not yet been achieved. This paper introduces a hybrid control topology that (1) utilizes comparator-based regulations for most outputs and (2) uses a new charge control loop method for the last output to reduce cross-regulation with low hardware complexity. In addition, the proposed scheme efficiently reuses the system’s redundant energy by adaptively controlling the freewheeling switch that opens the path to the input battery to store the surplus energy resources again. The proposed SIMO DC-DC converter was designed and validated with a 0.18 μm 3.3 V CMOS process. The converter has four regulated outputs of 0.9, 1.2, 1.5, and 2.2 V, and as a result of the simulation, it was found that the cross-regulation was estimated to be 0.4 mV/mA when the output current changes by ~200 mA. In addition, estimated peak power conversion efficiency of 88.5% was achieved at a total output power of 405 mW.

Deadbeat Control for Single-Inductor Multiple-Output DC–DC Converter With Effectively Reduced Cross Regulation

This article presents a deadbeat-based control approach for the single-inductor multiple-output (SIMO) dc-dc converter. The proposed approach contributes to effectively solve the cross-regulation problem by independently regulating different output voltages based on independent load currents. Unlike conventional model-based methods, which require the measurement of load currents, the proposed approach employs output current observers to replace current sensors. Furthermore, it obtains an excellent dynamic and steady-state voltage regulation performances. Details of the proposed controller and output current observer are discussed. For verifying the validity of the proposed approach, simulation and hardware experiments are conducted on a single-inductor dual-output (SIDO) buck converter platform. The corresponding results are analyzed and compared with the performances of the start-of-art methods.

Single‐inductor multiple‐output DC–DC converter with duty‐cycle‐constrained comparator control

An auto-buck-boost single-inductor multiple-output (SIMO) dc-dc converter with duty-cycle-constrained comparator control is presented in this Letter. Combined both comparator-based and duty-cycle-constrained controllers enable the dc-dc converter attaining fast transient response and low cross-regulation (CR). The proposed algorithm is independent of the precision of current sensor and suppresses CR robustly with the proposed tri-feedback loop control of comparator-based voltage control, duty-cycle-constrained distribution and average current control. The proposed scheme is suitable for auto-buck-boost SIMO dc-dc converter design for dynamic voltage scaling applications.

Current-Source-Mode Single-Inductor Multiple-Output LED Driver With Single Closed-Loop Control Achieving Independent Dimming Function

Single-inductor multiple-output (SIMO) light-emitting diode (LED) drivers have the advantages of being compact, efficient, and low cost. However, the voltage-to-current transfer function of each output of the SIMO converter is not independent, with significant cross regulation issues that necessitate the use of complex closed-loop control for achieving independent dimming function. This paper proposes a current-source-mode (CSM) SIMO dc-dc converter from duality principle, which is shown to be more suited for LED driving due to widened control range of the duty cycle and inherently inductor-less LED driving topology. The outputs of the CSM SIMO dc-dc converter are inherently independent, resulting in very simple control requirement involving only one closed-loop controller for providing the constant current feeder, and several simple open-loop controllers for independent dimmable driving of LEDs. Simultaneous voltage step-up and step-down of multiple outputs is an added feature that simplifies the input power source requirement, especially for portable applications. The whole system is simple, reliable, and low cost. Taking the CSM single-inductor dual-output dc-dc converter as an example, we illustrate the circuit operation and establish a small-signal model for facilitating the design of the feedback control. A direct duty-cycle dimming method is described. Experimental tests are presented for verification.

Model Predictive Voltage Control for Single-Inductor Multiple-Output DC–DC Converter With Reduced Cross Regulation

This paper presents a model predictive voltage control (MPVC) method for the single-inductor multiple-output (SIMO) dc-dc converter. The proposed MPVC method is able to solve the cross-regulation problem, which is a critical issue in SIMO dc-dc converters. The design of the proposed method including augmented state-space model, cost function, enumerated algorithm, and constraints for the SIMO dc-dc converter is discussed. Simulation for the influences of predict horizon N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sub> , control horizon N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</sub> , and Lagrange multiplier λ on the voltage ripple is conducted to guide the control parameters' setting for hardware implementation. Steady-state operation and dynamic performance of the proposed MPVC method are conducted in simulation and experiment based on the single-inductor dual-output (SIDO) buck converter to verify the proposed MPVC method. In addition, the comparison between the proposed method and state-of-art methods for the SIMO dc-dc converters is presented. Simulation and experimental results demonstrate that the MPVC method guarantees low cross regulation for the SIMO dc-dc converter in continuous-conduction mode (CCM) and has a fast response speed to variations in load and reference.

Research on a topology of single-inductor multiple-output DC-DC converter with high power conversion efficiency

This paper researches a topology of single-inductor multiple-output DC-DC converter with high power conversion efficiency. Compared with traditional single-inductor multiple-output converters whose output loads are fed only by the energy stored in inductors, the output voltage of this converter is provided by not only the energy stored in inductor but also the energy stored in capacitor. As a result, this converter achieves higher energy conversion efficiency. The circuit description and operation analysis of this converter are displayed and as examples, a single-inductor dual-output and a single-inductor triple-output converter are simulated. The results show that this topology achieves multiple output voltages with high power conversion efficiency.

Load-Balance-Independent High Efficiency Single-Inductor Multiple-Output (SIMO) DC-DC Converters

A single-inductor multiple-output (SIMO) DC-DC converter providing buck and boost outputs with a new switching sequence is presented. In the proposed switching sequence, which does not require any additional blocks, input energy is delivered to outputs continuously by flowing current through the inductor, which leads to high conversion efficiency regardless of the balance between the buck and boost output loads. Furthermore, instead of multiple output loop compensation, only the freewheeling current feedback loop is compensated, which minimizes the number of off-chip components and nullifies the need for the equivalent series resistance (ESR) of the output capacitor for loop compensation. Therefore, power conversion efficiency and output voltage ripples can be improved and minimized, respectively. Implemented in a 0.35- μm CMOS, the proposed SIMO DC-DC converter achieves high conversion efficiency regardless of the load balance between the two outputs with maximum efficiency reaching up to 82% under heavy loads.

Single Inductor Bipolar Outputs DC-DC Converter with Current Mode Control Circuit

Mobile equipment such as organic-EL display, digital still camera and so on re-quire both positive and negative power supply voltage to obtain high quality. Single InductorMultiple-Output (SIMO) DC-DC converter can provide a pair of positive and negative outputvoltages with only one external inductor. This paper describes SIMO DC-DC Converter usingproposed current-mode control (CMC) circuit. The proposed CMC circuit realizes high responsespeed for the change of load current. Spectre simulations with 0.18m CMOS process parameterare performed to verify the validity of the proposed converter. The simulation results indicatethat the proposed converter has higher response time compared with conventional converter.

A Single-Inductor Multiple-Output Switcher With Simultaneous Buck, Boost, and Inverted Outputs

Portable applications require multiple supplies with different output levels and some applications also require negative outputs. Single-inductor multiple-output (SIMO) switchers are a good for existing parallel output configurations. This study presents an SIMO dc-dc converter capable of generating buck, boost, and inverted outputs simultaneously. The operation of this class of converter being driven by the ripple in the inductor current the conventional averaging method does not work well. An inductor current ripple-based modeling approach has been proposed to accurately model and analyze the converter. The control, cross-coupling, and cross-regulation transfer functions, generated through the model, accurately represent the performance of the converter. The proof of concept has been carried out with discrete components on an in-house built PCB and the experimental results validating the steady state and ac responses of the converter are presented.

On-Chip Single-Inductor Multiple-Output Power Converter Design with Adaptive Cross Regulation and Supply Variation Control for Power-Efficient VLSI Systems

Dynamic voltage and frequency scaling (DVFS) algorithms are widely used power management techniques which enable the optimization of system-level power dissipation, energy consumption and operation performance. One cost-effective hardware-enabling platform to implement the DVFS is through single-inductor multiple-output (SIMO) DC-DC converters. However, the major drawback with such converters is cross regulation, which leads to undesired supply voltage variations. These variations have significant impact on modern VLSI applications, from the circuit to the system level. Based on these challenges, this paper presents a cross-layered design of two SIMO DC-DC converters with an adaptive freewheel switching technique. The proposed converters are able to minimize cross regulation by adaptively adjusting the freewheel switching durations and currents. This also increases the efficiency of the SIMO converters, by reducing the conduction losses due to the lossy freewheel switch. To verify the cross regulation performance of the SIMO converters, its influence on clock frequencies generated by a ring oscillator is investigated. By simulating various load transient conditions, it is shown that the SIMO converters are able to significantly minimize frequency variations. The operation of the converters is verified through transistor-based HSPICE simulation results, with a 130-nm CMOS process. The SIMO converter with the digital-based adaptive freewheel switching controller achieves a maximum efficiency of 93.2%, while the analog counterpart achieves a maximum efficiency of 93.4%. For a load change from 200 mA to 40 mA, the proposed technique reduces the conduction losses during the freewheel switching duration by 99.96%, compared with traditional methods.

Self-Reconfigurable Channel Data Buffering Scheme and Circuit Design for Adaptive Flow Control in Power-Efficient Network-on-Chips

This paper presents a self-reconfigurable channel data buffering scheme and circuit design for next-generation network-on-chips (NoCs). The design is optimized for power efficiency and data throughput, from system to circuit level. During network congestion, the buffering scheme realizes adaptive flow control by reconfiguring the channel buffers for online data storage. Once congestion is alleviated, data transmission resumes from the foremost buffer stage, thereby improving NoC throughput. It also achieves system-level power optimization through an integrated hardware-software codesign approach. Using software techniques such as dynamic voltage and frequency scaling, optimal voltages and frequencies are provided to the system through a hardware-based single-inductor multiple-output dc-dc converter platform. Meanwhile, power dissipation is further minimized through switched-capacitor delay control modules. A CMOS IC prototype has been fabricated, with 16-bit data transmission capability. It demonstrates 58.9% power saving over conventional designs. To achieve the same throughput, it consumes only 45.4% power of the best prior art. The flexibility of the buffering scheme, along with the integrated power management solution, allows it to be applied to most existing commercial NoC architectures.

Single-Inductor–Multiple-Output Switching DC–DC Converters

Emerging feature dense portable microelectronic devices pose several challenges, including demanding multiple supply voltages from a single miniaturized power-efficient platform. Unfortunately, the power inductors used in magnetic-based switching converters (which are power efficient) are bulky and difficult to integrate. As a result, single-inductor-multiple-output (SIMO) solutions enjoy popularity, but not without design challenges. This brief describes, illustrates, and evaluates how SIMO dc-dc converters operate, transfer energy, and control (through negative feedback) each of their outputs.

A Single-Inductor Switching DC–DC Converter With Five Outputs and Ordered Power-Distributive Control

An integrated five-output single-inductor multiple-output dc-dc converter with ordered power-distributive control (OPDC) in a 0.5 mum Bi-CMOS process is presented. The converter has four main positive boost outputs programmable from +5 V to +12 V and one dependent negative output ranged from -12 V to -5 V. A maximum efficiency of 80.8% is achieved at a total output power of 450 mW, with a switching frequency of 700 kHz. The performance of the converter as a commercial product is successfully verified with a new control method and proposed circuits, including a full-waveform inductor-current sensing circuit, a variation-free frequency generator, and an in-rush-current-free soft-start method. With simplicity, flexibility, and reliability, the design enables shorter time-to-market in future extensions with more outputs and different operation requirements.