MAX1644 Datasheet, PDF (28/32 Pages) Maxim Integrated Products – Advanced Chemistry-Independent, Level 2 Battery Charger with Input Current Limiting

Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
VCC
+12V, -12V
SYSTEM
POWER
SUPPLY
DC (UNREGULATED) / VBATTERY
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
VCHARGE
MAX1645
SMART
BATTERY
CHARGER
CRITICAL EVENTS
BATTERY DATA/STATUS REQUESTS
SMBus
Figure 11. Typical System Using Multiple Smart Batteries
Table 7. Smart Battery Charger Type
by SMBus Mode and Charge Algorithm
Source
CHARGE ALGORITHM SOURCE
SMBus MODE
BATTERY
MODIFIED FROM
BATTERY
Slave only
Slave/Master
Level 2
Level 3
Level 3
Level 3
Note: Level 1 smart battery chargers were 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 to
respond to the smart battery’s ChargingVoltage() and
ChargingCurrent() messages. The charger is obliged to
adjust its output characteristics in direct response to
the ChargingVoltage() and ChargingCurrent() mes-
sages it receives from the battery. In Level 2 charging,
the smart battery is completely responsible for initiating
the communication and providing the charging algo-
rithm to the charger.
The smart battery is in the best position to tell the smart
battery charger how it needs to be charged. The charg-
ing 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-
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