Specifications

Smart Battery Charger Specification
SBS Implementers Forum -Page 30- Revision 1.1
Appendix D. Implementation Examples
SMBus components, including Smart Battery Chargers and Smart Batteries, are versatile and allow great
variety in the specific hardware implementations while still retaining software and inter-operability
compatibility. The following sections of this appendix describe several examples of specific
implementations that use some or all of the features of the SMBus, Smart Battery or Smart Battery Charger.
Emulating a Smart Battery Charger with the Host
The System Host, Smart Battery Charger and Smart Battery Selector are defined as separate logical entities
but may be implemented in shared physical resources. A dedicated or shared micro-controller equipped
with a SMBus interface may be made to emulate a Smart Battery Charger and/or a Smart Battery Selector.
In many cases this will be the SMBus Host, but it may also be a SMBus Slave device configured to control
the charger electronics. As in the example given above for Notebook Computers, the charger may use one
or more I/O lines to set the charge conditions of the charging electronics, but in this case the controller
must interpret Smart Battery Charger commands given over the SMBus in order to properly set the charge
electronics. Likewise, the controller must interpret the Safety Signal value and respond appropriately.
Finally, in emulating the Smart Battery Charger, the controller must respond to the appropriate Smart
Battery Charger functions, including properly reporting the charger level.
System Host
Charger Power
Section
Smart Battery
Vbatt
Critical Events
Battery Data/Status Requests & Charging Current/Voltage Requests
SMBus
AC-DC
Converter
AC
Safety
Signal
Host Emulation of SBCharger
(Unregulated)
Charge Power Control
The keyboard controller as Host
An existing micro-controller may be used to implement a SMBus connection from the system to the Smart
Battery and Smart Battery Charger. Again using the Notebook Computer as an example, the existing
keyboard controller (often an 80C51SL or H8 style micro-controller) may be used to perform SMBus I/O
in addition to the existing tasks. Specifics of the I/O structure and timing may be in dedicated hardware or
via software emulation. In either method, the controller links the SMBus devices, including the Smart
Battery and Smart Battery Charger with the system. The Host controller must recognize its own address as
well as responding properly to system calls for SMBus devices (refer to the References section).