Smart Battery System Specifications Smart Battery Charger Specification Revision 1.1 December 11, 1998 Copyright 1996, 1997, 1998, Benchmarq Microelectronics Inc., Duracell Inc., Energizer Power Systems, Intel Corporation, Linear Technology Corporation, Maxim Integrated Products, Mitsubishi Electric Corporation, National Semiconductor Corporation, Toshiba Battery Co., Varta Batterie AG, All rights reserved.
Questions and comments regarding this specification may be forwarded to: Email: charger@sbs-forum.org Or: questions@sbs-forum.org For additional information on Smart Battery System Specifications, visit the SBS Implementer’s Forum (SBS-IF) at: www.sbs-forum.org THIS SPECIFICATION IS PROVIDED "AS IS" WITH NO WARRANTIES WHATSOEVER, INCLUDING ANY WARRANTY OF MERCHANTABILITY, NONINFRINGEMENT, FITNESS FOR ANY PARTICULAR PURPOSE, OR ANY WARRANTY OTHERWISE ARISING OUT OF ANY PROPOSAL, SPECIFICATION OR SAMPLE.
Smart Battery Charger Specification Table of Contents 1. INTRODUCTION 1 1.1. Scope 1 1.2. Audience 1 2. REFERENCES 2 3. DEFINITIONS 2 4. SMART BATTERY CHARGING SYSTEM 3 4.1. Smart Battery System Block Diagrams 3 4.2. Smart Battery Charger Types 4.2.1. Level 2 Smart Battery Charger 4.2.2. Level 3 Smart Battery Charger 5 5 5 4.3. Interface Definition 4.3.1. Typical Communications between a Smart Battery-and-Smart Battery Charger 4.3.2.
Smart Battery Charger Specification 6.1.6. “Float” Voltage 6.1.7. Smart Battery Charger Start-Up 6.1.8. Charger Operational Modes Clarifications 6.1.9. Optional Smart Battery Charger Registers for Selector Support 6.1.10. Optional Charger Interrupt Mechanism 6.1.11. Battery Internal Charge Control 20 20 21 23 23 23 6.2. Level 2 Smart Battery Charger Characteristics 6.2.1. Required Commands 6.2.2. Charge Initiation 6.2.3. Charge Termination 6.2.4. Charge Current and Voltage 24 24 24 24 24 6.3.
Smart Battery Charger Specification Revision History Revision Number 0.95 0.95a 1.0 1.1 Date 9/28/94 2/15/95 6/27/96 12/11/98 SBS Implementers Forum Author R Dunstan R Dunstan R Dunstan B Rush Notes Initial Public release Added optional manufacturer command codes Version 1.0 Release Version 1.1 Release -Page iii- Revision 1.
Smart Battery Charger Specification 1. Introduction The Smart Battery Charger Specification presents one element of a complete system solution for rechargeable batteries used in portable electronic equipment such as laptop computer systems, cellular telephones and video cameras.
Smart Battery Charger Specification 2. References • • • • • • • • Smart Battery Data Specification, Revision 1.1, SBS-Implementers Forum, December, 1998 Smart Battery Selector Specification, Revision 1.1, SBS-Implementers Forum, December, 1998 Smart Battery System Manager Specification, Revision 1.1, SBS-Implementers Forum, December, 1998 System Management Bus Specification, Revision 1.1, SBS-Implementers Forum, December, 1998 System Management Bus BIOS Interface Specification, Revision 1.
Smart Battery Charger Specification 4. Smart Battery Charging System A Smart Battery Charging System at a minimum consists of a Smart Battery and Smart Battery Charger compatible with this specification and those described in the references section. 4.1. Smart Battery System Block Diagrams A system may use one or more Smart Batteries.
Smart Battery Charger Specification Vcc, +12v, -12v System Power Supply AC DC (Unregulated/battery) Note: SB #1 powering system SB #2 charging AC-DC Converter (Unregulated) SMBus Safety Signal Smart Battery #2 Vbatt SMBus Safety Signal Vbatt Smart Battery #1 SMBus System Host (SMBus Host) Smart Battery Selector Safety Signal Smart Battery Charger VCharge Critical Events SMBus Battery Data/Status Requests Typical Multiple Smart Battery System The block diagram above shows a two-battery
Smart Battery Charger Specification 4.2. Smart Battery Charger Types Two types of Smart Battery Chargers are defined: Level 2 and Level 3. This document defines a particular set of characteristics and minimum command set for each type of Smart Battery Charger. All Smart Battery Chargers communicate with the Smart Battery using the SMBus; the two types differ in their SMBus communication mode and whether they modify the charging algorithm of the Smart Battery.
Smart Battery Charger Specification than a Level 2 charger. In some cases, a system designer may choose to use the system host to communicate with both the Smart Battery and a Level 2 Smart Battery Charger to provide a hybrid Level 3 functionality. 4.3.
Smart Battery Charger Specification 4.4. Error Detection and Signaling The Smart Battery Charger supports the SMBus method for error signaling. This error system is designed to minimize the amount of traffic on the SMBus and the amount of code required to communicate with the charger. 4.4.1.
Smart Battery Charger Specification 5. Smart Battery Charger Commands The battery or the charger, depending upon the specific implementation may initiate communication between the Smart Battery and Smart Battery Charger. In either case, the same minimum set of information is transmitted between the battery and the charger.
Smart Battery Charger Specification The functions are described as follows: FunctionName() 0xnn (command code) Description: A brief description of the function. Purpose: The purpose of the function, and an example where appropriate. Supported by: This function must be supported by the charger level specified.
Smart Battery Charger Specification 5.1. Smart Battery Charger Slave Functions (battery or host-to-charger) The following functions are performed by the charger operating as a SMBus slave device. They are required functions for a Smart Battery Charger. Any master device, typically the Smart Battery, or the system host operating as a master, initiates these functions. 5.1.1. ChargingCurrent() (0x14) Description: The Battery, System Host or other master device sends the desired charging rate (mA).
Smart Battery Charger Specification 5.1.2. ChargingVoltage() (0x15) Description: The Battery, System Host or other master device sends the desired charging voltage to the Smart Battery Charger (mV). Purpose: The ChargingVoltage() function sets the maximum voltage that a Smart Battery Charger may deliver to the Smart Battery. In combination with the ChargingCurrent() function and the battery's internal impedance, this function determines the Smart Battery Charger's desired operating point.
Smart Battery Charger Specification Charger and/or the System Host to identify the Smart Battery as the source of the AlarmWarning() message. All alarm conditions are sent to the System Host but only those alarms relating to charging are sent to the Smart Battery Charger. Purpose: The AlarmWarning() sent by the Smart Battery may be used by the System Host to notify the user about Alarms generated by the Smart Battery.
Smart Battery Charger Specification Input: unsigned int - bit mapped - see below Units: not applicable Range: not applicable Granularity not applicable Accuracy: not applicable Field Bits Used Format INHIBIT_CHARGE 0 bit flag ENABLE_POLLING 1 bit flag POR_RESET 2 bit flag RESET_TO_ZERO 3 bit flag Reserved 4...
Smart Battery Charger Specification Field Bits Used Format CHARGE_INHIBITED 0 bit flag POLLING_ENABLED 1 bit flag VOLTAGE_NOTREG 2 bit flag 3 bit flag LEVEL_2 4 bit flag LEVEL_3 5 bit flag CURRENT_OR 6 bit flag VOLTAGE_OR 7 bit flag RES_OR 8 bit flag RES_COLD 9 bit flag RES_HOT 10 bit flag RES_UR 11 bit flag ALARM_INHIBITED 12 bit flag POWER_FAIL 13 bit flag BATTERY_PRESENT 14 bit flag AC_PRESENT 15 bit flag (OPTIONAL) CURRENT_NOTREG (OPTIONAL) Allowable
Smart Battery Charger Specification LEVEL_3 bit is set if the charger is capable of operating as a Level 3 Smart Battery Charger. Note: A LEVEL_3 charger must be able to operate as a LEVEL_2 charger when the ENABLE_POLLING bit is cleared. CURRENT_OR bit is set only when ChargingCurrent() is set to a value outside the current regulation range of the charger.
Smart Battery Charger Specification Output: unsigned int - bit mapped - see below Units: not applicable Range: not applicable Granularity not applicable Accuracy: not applicable Field Bits Used Format CHARGER_SPEC 0…3 Bit flag SELECTOR_SUPPORT 4 bit flag Reserved 5…15 bit flag Allowable Values The CHARGER_SPEC reports the version of the Smart Battery Charger specification the charger it supports: 0001 – Version 1.0. 0010 – Version 1.1 (this version of the spec) 0011 – Version 1.
Smart Battery Charger Specification Smart Battery. In combination with the ChargingVoltage() function and the battery's internal impedance, this function determines the Smart Battery Charger's desired operating point. Together, these functions permit a Smart Battery Charger to dynamically adjust its charging profile (current/voltage) for optimal charge. The Smart Battery can effectively turn off the Smart Battery Charger by returning 0 for this function.
Smart Battery Charger Specification Supported by: Level 3 Charger SMBus Protocol: Write Word Output: unsigned int -- charger output voltage in mV Units: mV Range: data range is 0 to 65,534 mV output range is defined by the specific implementation, but not less than 8 bits within the 16 bit field Granularity: 0.
Smart Battery Charger Specification 6. Smart Battery Charger Characteristics Smart Battery Chargers are differentiated by their type (see Smart Battery Charger types in this document). Each type has certain characteristics and supports certain functions. This section describes the characteristics and functions all chargers have in common as well as those that are type specific. 6.1.
Smart Battery Charger Specification 6.1.4. Charger Brown-Out Conditions Situations may arise where the system attempts to charge a battery while the system is also being powered from the AC power supply. In these cases, the charger may not draw so much power that the system’s power source is compromised. The charger can, at its option, choose to charge the battery at a lower rate automatically or abort charging entirely.
Smart Battery Charger Specification 6.1.8. Charger Operational Modes Clarifications The following diagram illustrates a state machine implementation of the Smart Battery Charger’s operational states. The table afterward describes the state transitions.
Smart Battery Charger Specification 5 The charger is supplying “wake-up” charge to the battery (from condition 1 above) AND RES_HOT changes from 0 to 1. 6 The charger is supplying “wake-up” charge to the battery (from condition 2 above) and RES_UR changes from 1 to 0. 7 The charger is applying “wake-up” charge to the battery AND INHIBIT_CHARGE is set to 1.
Smart Battery Charger Specification 6.1.9. Optional Smart Battery Charger Registers for Selector Support To support implementations of a Smart Battery Charger and Smart Battery Selector combined in the same component, optional charger command codes have been defined. These codes are optional and only used by charger components that also include selector functionality. Their presence is indicated by the SELECTOR_SUPPORT bit in the ChargerSpecInfo() function.
Smart Battery Charger Specification 6.2. Level 2 Smart Battery Charger Characteristics 6.2.1. Required Commands AlarmWarning() ChargingCurrent() ChargingVoltage() ChargerSpecInfo() ChargerMode() ChargerStatus() 6.2.2. Charge Initiation Level 2 chargers may initiate charge: • upon insertion of a battery • when charge power becomes available • when ChargingVoltage() and ChargingCurrent() are both set to non-zero values • when the AlarmWarning() is written without critical error bits set.
Smart Battery Charger Specification initiates polling and therefore charging, it is suggested that the Level 3 Smart Battery Charger disable the automatic broadcasts of the battery by setting Battery Mode CHARGER_MODE bit. See the Smart Battery Data Specification for details (refer to the References section). 6.3.3.
Smart Battery Charger Specification Appendix A. Smart Battery Charger command set in tabular form The following tables summarize the charger commands by: the function name, command code, access (r,w), data type and applicability. For a battery charger to be recognized as a Smart Battery Charger, it must support all the functions described by this specification for its level of implementation.
Smart Battery Charger Specification Appendix B. Smart Battery System Safety Features Safety is a primary design goal in the Smart Battery System specifications. The central concept behind the Smart Battery specifications is locating the primary intelligence of the system inside the battery pack itself.
Smart Battery Charger Specification since it will no longer be receiving messages from the battery.) Second, the charger will monitor the battery pack Safety Signal terminal. If the Safety Signal moves out of a range that allows “controlled” charging, the charger will immediately terminate charge. This could happen if the temperature of the battery pack got too hot, or the intelligence in the pack could force the Safety Signal to that range to indicate an error condition and abort charging immediately.
Smart Battery Charger Specification Appendix C. Smart Battery Alarm Bits Alarm Bits OVER_CHARGED_ALARM bit is set whenever the Smart Battery detects that it is being charged beyond an end-of-charge indication. This bit will be cleared when the Smart Battery detects that it is no longer being over-charged. TERMINATE_CHARGE_ALARM bit is set when the Smart Battery detects that one or more of its charging parameters are out of range (e.g. its voltage or current are too high).
Smart Battery Charger Specification 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.
Smart Battery Charger Specification No-host charging Because the Smart Battery can communicate as a Master device on the SMBus, no Host device is required for proper charging. Host electronics may be completely shut off and, as long as power is provided to charge, the Smart Battery and Smart Battery Charger may communicate independent of the Host.
Smart Battery Charger Specification Vbatt AC System Host Smart Battery Safety Signal (Master-mode only) Smart Battery Charger AC-DC Converter (Unregulated) Critical Events SMBus Battery Data/Status Requests Charging Voltage/Current Requests Master-mode only Host Non-DC Charging Previous discussion of the charger output of ChargingCurrent() and ChargingVoltage() values has assumed that the charger output contained no AC component.
Smart Battery Charger Specification Appendix E. Accuracy Requirements This specification places minimum accuracy requirements for ChargingCurrent() and ChargingVoltage() on all Smart Battery Chargers to ensure basic operability between SBS system components. The body of the specification is purposely kept generic with regard to cell chemistry, pack voltage, pack capacity in keeping with the scope defined in Section 1.1.
Smart Battery Charger Specification resulting charge condition is unsuitable, the Smart Battery could send new values to the Smart Battery Charger as in the following example: 1. The Smart Battery sets the ChargingCurrent() of the Smart Battery Charger to 1A 2. The Smart Battery Charger responds by providing 0.95A, within its ±5% accuracy requirement. 3. The Smart Battery measures the charge current of 0.95A and calculates a new target of 1A/0.95A = 1.
