MAX1667 Datasheet, PDF (11/28 Pages) Maxim Integrated Products – Chemistry-Independent, Level 2 Smart Battery Charger

Chemistry-Independent,
Level 2 Smart Battery Charger
V_CC
+12V, -12V
SYSTEM
POWER
SUPPLY
DC (UNREGULATED) / V_BATTERY
NOTE: SB 1 POWERING SYSTEM
SB 2 CHARGING
SMART BATTERY 1
SMART BATTERY 2
AC
AC-DC
CONVERTER
(UNREGULATED)
SYSTEM HOST
(SMBus HOST)
SMART BATTERY
SELECTOR
SMBus
SAFETY SIGNAL
V_CHARGE
MAX1667
SMART BATTERY
CHARGER
CRITICAL EVENTS
BATTERY DATA/STATUS REQUESTS
SMBus
Figure 4. Typical Multiple Smart Battery System
Table 1. Charger Type by SMBus Mode
and Charge Algorithm Source
SMBus MODE
Slave Only
Slave/Master
CHARGE ALGORITHM SOURCE
Battery
Modified from Battery
Level 2
Level 3
Level 3
Level 3
Note: Level 1 smart battery chargers are defined in the ver-
sion 0.95a specification. While they can correctly interpret
smart battery end-of-charge messages minimizing over-
charge, they do not provide truly chemistry-independent
charging. They are no longer defined by the Smart Battery
Charger specification and are explicitly not compliant with this
and subsequent Smart Battery Charger specifications.
Level 2 Smart Battery Charger
The Level 2 or “smart-battery-controlled” smart battery
charger interprets the smart battery’s critical warning
messages, and operates as an SMBus slave device
that responds to ChargingVoltage() and Charging-
Current() messages sent to it by a smart battery. The
charger is obliged to adjust its output characteristics in
direct response to the messages it receives from the
battery. In Level 2 charging, the smart battery is com-
pletely responsible for initiating communication and for
providing the charging algorithm to the charger. The
smart battery is in the best position to tell the smart bat-
tery charger how it needs to be charged. The charging
algorithm in the battery may request a static charge
condition or may choose to periodically adjust the
smart battery charger’s output to meet its present
needs. A Level 2 smart battery charger is truly chem-
istry independent, and since it is defined as an SMBus
slave device only, it is relatively inexpensive and easy
to implement.
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