Feature: Batteries
Figure 1. A simplified system diagram of a battery-operated system
Designing for optimal power conversion efficiency in battery- powered systems
By Frederik Dostal, Field Applications Engineer, Analog Devices
Question: Is a power management system required for battery-powered systems?
Answer: Yes, most battery-powered systems need to implement a battery charging concept. In this article, we describe how different power management functions are designed and optimised for battery-operated systems. An example system diagram that contains many of the functions that are needed in battery-powered electronics is introduced. Different aspects
32 April 2025
www.electronicsworld.co.uk
of power conversion efficiency are also discussed. Many systems require battery power. Batteries are used for
power redundancy in case of a line power outage, but mostly in portable equipment, which can be large like an electric vehicle or small like a hearing aid. In all battery-powered systems, power efficiency is key. Te less efficient the power supply, the larger and more costly the battery for the same runtime. Also, batteries supply different voltages depending on the charge state. Tis requires special power converter capability to regulate the varying voltage from the batteries to a stable voltage for the system electronics. Most battery-powered systems today implement a rechargeable
battery rather than a primary non-rechargeable battery. Tis requires systems to include a battery charger. Tis article explains various battery charging architectures along with new, innovative examples. Certainly, power conversion efficiency is a must. Figure 1 shows a system diagram of a battery-operated system.
While the exact implementation varies for different use cases, the main function blocks shown in this diagram are usually available in all systems. Tere is some supply voltage, which sources the power to the system. Tis connection oſten needs to be switchable. If the power source is a wall wart AC line power converter, unplugging the low voltage power cable is the same action as switching the power switch in Figure 1 to the off position. Such power path management is necessary to avoid losing valuable battery energy to additional circuitry attached to the source. Also in Figure 1, we see a potential second power source. Te
power switch block would switch the power flow coming from Power Source 1 or Power Source 2. For example, Power Source 2 may be a USB 5V power source. Then the power is converted to safely charge the available
battery and/or to power the system directly. If no input power is available, the stored energy in the battery is taken with a very high efficiency switch-mode power converter to power the system.
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