MAX1645 Datasheet, PDF (28/32 Pages) Maxim Integrated Products – Advanced Chemistry-Independent, Level 2 Battery Chargers with Input Current Limiting

Advanced Chemistry-Independent, Level 2
Battery Chargers with Input Current Limiting
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
MAX1645A
SMART
BATTERY
CHARGER
CRITICAL EVENTS
BATTERY DATA/STATUS REQUESTS
SMBus
Figure 11. Typical System Using Multiple Smart Batteries
Table 8. Smart Battery Charger Type
by SMBus Mode and Charge Algorithm
Source
SMBus MODE
CHARGE ALGORITHM SOURCE
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.
connect batteries to the smart battery charger or the
system, or to disconnect them, as appropriate. For
each battery, three connections must be made: power
(the battery’s positive and negative terminals), the
SMBus (clock and data), and the safety signal (resis-
tance, typically temperature dependent). Additionally,
the system host must be able to query any battery so it
can display the state of all batteries present in the system.
Figure 11 shows a two-battery system where battery 2
is being charged while battery 1 is powering the sys-
tem. This configuration may be used to “condition” bat-
tery 1, allowing it to be fully discharged prior to
recharge.
Smart Battery Charger Types
Two types of smart battery chargers are defined: Level 2
and Level 3. 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
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