High Efficiency DC-DC Converters for Battery- Operated Systems with Energy Management

Dc-dc converters suitable for use in battery-powered electronic equipment with energy management are discussed. To realize the benefits of energy management, these converters must be capable of maintaining regulation of their output voltages at no load, while maintaining high efficiency. Variable frequency operation is shown to give an improvement in efficient operating range of approximately two orders of magnitude. Proportionality of the battery and load currents can be maintained over approximately five orders of magnitude, with minimum battery currents of less than 100μA and maximum load currents approaching 10A. Steady-state and small-signal ac characteristics of converters operating with variable-frequency control are tabulated, and an ac two-port model is described.