Scalability of quasi-hysteretic fsm-based digitally controlled single-inductor dual-string buck led driver to multiple strings

Albert T.L. Lee, Johnny K.O. Sin, Philip Ching Ho Chan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

65 Citations (Scopus)


There has been growing interest in single-inductor multiple-output (SIMO) dc-dc converters due to its reduced cost and smaller form factor in comparison with using multiple single-output converters. An application for such a SIMO-based switching converter is to drive multiple LED strings in a multichannel LED display. This paper proposes a quasi-hysteretic finite-state-machine-based digitally controlled single-inductor dual-output buck switching LED driver operating in discontinuous conduction mode (DCM) and extends it to drive multiple outputs. Based on the time-multiplexing control scheme in DCM, a theoretical upper limit of the total number of outputs in a SIMO buck switching LED driver for various backlight LED current values can be derived analytically. The advantages of the proposed SIMO LED driver include reducing the controller design complexity by eliminating loop compensation, driving more LED strings without limited by the maximum LED current rating, performing digital dimming with no additional switches required, and optimization of local bus voltage to compensate for variability of LED forward voltage $VF in each individual LED string with smaller power loss. Loosely binned LEDs with larger $VF variation can, therefore, be used for reduced LED costs.
Original languageEnglish
Article number6482650
Pages (from-to)501-513
Number of pages13
JournalIEEE Transactions on Power Electronics
Issue number1
Publication statusPublished - 1 Jan 2014


  • Boundary conduction mode (BCM)
  • discontinuous conduction mode (DCM)
  • finite-state machine (FSM)
  • single-inductor dual-output (SIDO)
  • single-inductor multiple-output (SIMO)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

Cite this