ABSTRACT
Chapter 2 discusses the general aspects of SIMO DC-DC converters. It talks about the four major power stage topologies, namely SIMO buck, SIMO boost, SIMO inverting buck-boost, and SIMO noninverting buck boost. The mathematical representation of each of these topologies is also given. This is followed by a description of the two key control methods, namely hysteretic and pulse-width modulation control. In particular, this chapter also explains how these two control methods can actually be used to realize the multiple-energizing and single-energizing switching sequence for SIMO converters with closed-loop control. Regardless of the underlying method, the challenge is to combine multiple feedback paths to generate switch-control signals at the appropriate times for achieving precise and independent control of multiple outputs. On the other hand, it is also interesting to discover the scalability limits of SIMO topology. Specifically, the theoretical maximum achievable number of outputs of a SIMO DC-DC LED driver given a set of design constraints is investigated. This leads to the formulation of scalability models for SIMO LED driver operating in boundary conduction mode, discontinuous conduction mode and pseudo-continuous conduction mode, which enables the prediction of the maximum possible number of outputs (or LED strings) of a SIMO LED driver with a given design specification.
