Load switches get smart [battery life improvement]

New ultra-portable designs must combine increased functionality while extending battery life in constantly shrinking form factors. This paper shows how power utilisation has to be carefully managed in order for this shift in emphasis to be achieved. The function of connecting operating blocks to the battery is known as load switching. A power management controller enables the power switch with a logic level; this switch is often referred to as the load switch. Typically, load switches are implemented using two MOSFETs, one as a pass device and the other to hard switch the pass FET on or off. This implementation has been very effective multiplexing battery power to the areas where it is needed and powering off when idle. In comparison, the latest generations of these load switches incorporate complex functions to better perform this switching operation. While these functions have long been implemented discretely when required, the new target form factors for today's products no longer have space for this type of implementation.