Most battery-powered portable equipment requires one or more step-up DC/DC converters
to provide higher supply voltages
to other components such as LCDs. Because power consumption must be minimised, these components are placed in sleep or shutdown mode when not in use. Many step-up DC/DC converters have a shutdown input (SHDN) for this purpose, but they are not capable of complete shutdown because all such converters have an essential current
path between input and output via the inductor
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