Programmable Digital Controller for Multi-Output DC-DC Converters with a Time-Shared Inductor

This paper introduces a low power digital PFM controller for multi-output dc-dc converters suitable for integration in modern low-power management systems. It utilizes only one inductor to provide multiple output voltages and has very low power consumption. In addition, its reference voltages and switching frequency can be programmed dynamically. To achieve these characteristics two new key functional blocks are developed, namely Σ-Δ programmable delay-line based comparator utilizing natural filtering of delay cells and on-time control logic. The controller is implemented both on FPGA and a 0.18-μm CMOS application specific IC. Experimental results obtained with a 1 W, 9 V, four-output buck prototype and IC simulations successfully verify controller operation.

[1]  Chi-Ying Tsui,et al.  A pseudo-CCM/DCM SIMO switching converter with freewheel switching , 2002, 2002 IEEE International Solid-State Circuits Conference. Digest of Technical Papers (Cat. No.02CH37315).

[2]  Aleksandar Prodic,et al.  High-frequency digital PWM controller IC for DC-DC converters , 2003 .

[3]  Robert W. Erickson,et al.  Modeling of cross-regulation in converters containing coupled inductors , 1998, APEC '98 Thirteenth Annual Applied Power Electronics Conference and Exposition.

[4]  Anantha Chandrakasan,et al.  High-efficiency multiple-output DC-DC conversion for low-voltage systems , 2000, IEEE Trans. Very Large Scale Integr. Syst..

[5]  Mark Horowitz,et al.  Clustered voltage scaling technique for low-power design , 1995, ISLPED '95.

[6]  Chi-Ying Tsui,et al.  Single-inductor multiple-output switching converters with bipolar outputs , 2001, ISCAS 2001. The 2001 IEEE International Symposium on Circuits and Systems (Cat. No.01CH37196).

[7]  Kaushik Roy,et al.  Scheduling and optimal voltage selection for low power multi-voltage DSP datapaths , 1997, Proceedings of 1997 IEEE International Symposium on Circuits and Systems. Circuits and Systems in the Information Age ISCAS '97.

[8]  L. S. Nielsen,et al.  Low-power operation using self-timed circuits and adaptive scaling of the supply voltage , 1994, IEEE Trans. Very Large Scale Integr. Syst..

[9]  A. Prodic,et al.  Digital Pulse-Frequency/Pulse-Amplitude Modulator for Improving Efficiency of SMPS Operating Under Light Loads , 2006, 2006 IEEE Workshops on Computers in Power Electronics.

[10]  David A. Johns,et al.  Analog Integrated Circuit Design , 1996 .

[11]  Massoud Pedram,et al.  Energy Minimization Using Multiple Supply Voltages , 1997 .

[12]  D. Maksimovic,et al.  Digital pulse width modulator architectures , 2004, 2004 IEEE 35th Annual Power Electronics Specialists Conference (IEEE Cat. No.04CH37551).

[13]  A. Prodic,et al.  Multimode digital SMPS controller IC for low-power management , 2006, 2006 IEEE International Symposium on Circuits and Systems.

[14]  Chi-Ying Tsui,et al.  Single-inductor multiple-output switching converters with time-multiplexing control in discontinuous conduction mode , 2003, IEEE J. Solid State Circuits.

[15]  Takashi Ishikawa,et al.  Automated low-power technique exploiting multiple supply voltages applied to a media processor , 1997, Proceedings of CICC 97 - Custom Integrated Circuits Conference.