High-efficiency, high-density power supplies have been a trend for communications equipment due to increasing power consumption and reduced board space. A stacked-FET switch enables high-efficiency and high-density solutions. Two real design examples are examined to illustrate this point. The first is a 30-A design where the benefits of a stacked-FET switch are evaluated relative to size reduction, efficiency gain and thermal budget savings. A second design implements the stacked-FET switch with an integrated driver to further increase system efficiency in a 60-A supply.

As modern electronics equipment advances in speed and performance, the number of power rails keeps increasing in addition to an increase in power consumption. Conversely, the physical area for power supplies keeps shrinking because precious real estate is given to the core ASIC and processors. As such, a high-efficiency, high-density power supply is a challenge for every power designer.

The new Tiva C Series ARM® Cortex™–M4 family of versatile microcontrollers provides prolific connectivity peripherals, such as the industry's first integrated Ethernet MAC and PHY, advanced analog integration and hardware floating-point performance. The TM4C123x and TM4C129x family of microcontrollers can be configured to operate in different power modes such as hibernation mode, deepsleep mode, sleep mode and run mode to optimize the balance between power consumption and performance to suit a wide range of end-applications. High-efficiency at both very low power consumption (deep-sleep mode and hibernation mode) and high performance (run mode at full system clock speed) has become indispensable for modern applications. Moreover, in handheld, battery-operated applications that simultaneously connect, communicate and control, high-efficiency power management is imperative to extend the battery stand-by time. This application report presents an ultra-low IQ (4.8 μA) power supply solution for Tiva C Series devices using the TPS62177, a high efficiency synchronous step-down DC-DC converter, based on the DCS-Control (Direct Control with Seamless Transition into Power Save Mode) topology. The TPS62177 interfaces seamlessly with Tiva C Series devices' low power modes, meeting the power requirements of embedded systems driven from 2- to 6-cell lithium batteries, as well as USB ports and higher voltage AC adaptors.