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tions passed are key factors for international marketing success. Device manufacturers have little influence on these factors, so choosing wisely when selecting a suitable battery pack is important. Power distribution A Smart Battery Manager (SBM) converts the voltage of the power supply or battery pack into different voltage levels for the application. If the device has more than one battery or if it is additionally supplied by the mains, the SBM distributes loads and currents dynamically as directed by the internal microcontroller. To enable device manufacturers to quickly develop a mobile device, computer module manufacturer congatec has created the SBM3 module as a reference design that supports up to two battery packs in the configurations 2S to 4S. The SBM3 is designed for input voltages from 8 V to 30 V and thus covers all common input ranges. For the application the SBM3 converts the input voltage to 12 V and two times 5 V. The reference design includes all possible options, and the conga-SBM3 Development Licence Kit provides all necessary How the Smart Battery subsystem works. information and documentation. This allows OEMs to design application-specific devices in a cost-effective way. For example, if a high input voltage of 30 V is not needed, hardware optimizations can reduce costs by up to a third. The SBM3 includes the STM32F100 32-bit ARM microcontroller. It communicates with both the battery and the COM’s on-board controller and forms part of the logical interface between the power management of the operating system with ACPI support (e.g. Windows or Linux) and the physical hardware. The ACPI (Advanced Configuration and Power Interface) is the key element of the power management in the operating system. Before the introduction of ACPI, the power management functions and board-specific configurations were traditionally implemented in the BIOS. BIOS solutions were limited to static hardware configurations. The trend is now moving away FUJITSU Presents new developments at Electronica 2014 device, such as I/O or HD, can be switched off selectively via Device Power States, the S-States define various levels of sleep modes and the C-States regulate the CPU power. Here lies a wide field of opportunities to influence the power consumption. Communication with the battery subsystem works the same as in commercial notebooks, via so-called control methods in the ACPI BIOS. For this reason, such a battery solution is referred to as CMB, Control Method Battery. As the name suggests, individual ACPI functions, the Control Methods. The two most important are _BIF (Battery Information) and _BST (Battery Status). _BIF sends static battery information, such as serial number, design voltage and model number to the ACPI OS. _BST, on the other hand, provides dynamically changing battery data such as charge status or remaining capacity. These methods the link between the operating system and the battery hardware. respond to any changes in the battery condition. This handler is also implemented in the congatec ACPI BIOS and ensures that the operating system is notified of any change in the battery subsystem, for example when the network adapter is connected or disconnected. In this case, the power icon in the Windows status bar will be updated within seconds. From the device manufacturer’s perspective, batteries are just a sideshow. His focus, naturally, is on the application. But the success of a device depends to a large extent on an intelligent The latest product developments at the Electronica 2014 On Resistive Touch Panels, Thermal Printers, Relays, Wireless Modules, Connectors Visit us at Hall B5, stand 343 www.emea.fujitsu.com/components from Advanced Power Management (APM) or BIOS implementations towards ACPI-compatible operating systems. Managing power consumption To make the available energy last as long as possible, smart power management is needed. The ACPI is a key element of clever power management. It is integrated into the operating system and communicates with the SBM3. The ACPI controls the total energy consumption via defined Power States. Individual components of the the software interface to the battery system consists of are implemented in the congatec ACPI BIOS and provide In addition, there is an event handler that needs to quickly Hall B5 Stand 343 and optimized power supply. www.electronics-eetimes.com Electronic Engineering Times Europe November 2014 35


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