Specifications

Smart Battery Charger Specification
SBS Implementers Forum -Page 18- Revision 1.1
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: 0.4% (8 bits) or better, monotonic
Minimum Accuracy: +1/-9% of the programmatic maximum voltage while
operating in constant voltage mode with sufficient input power to
regulate to the ChargingVoltage() value. If VOLTAGE_NOTREG or
VOLTAGE_OR bits in ChargerStatus() are set, the charge voltage may
be less than (programmatic maximum – 9%). See Appendix E for a
discussion on system design alternatives for improved charging
accuracy.
Invalid Data Indication: 65,535 indicates the battery needs a constant current at the
ChargingCurrent() value.
Note1: This is the same value as that listed in 5.1.2. In the case shown here, the value is read by the
Smart Battery Charger from the Smart Battery.
Note2: The Smart Battery Charger responds to voltage requests in one of three ways:
• supply the voltage requested
• supply the programmatic maximum voltage if the request is greater than its programmatic
maximum and less than 65535
• supply its maximum safe voltage if the request is 65535
Note3: The SBS specifications allow a Smart Battery to adjust its ChargingCurrent() and
ChargingVoltage() values in response to the Smart Battery Charger’s output. This technique
allows the Smart Battery to fine tune the Smart Battery Charger’s output, thus reducing the
accuracy requirements of the Smart Battery Charger. The Smart Battery’s algorithm must safely
control the Smart Battery Charger’s output under all conditions.