MAX1645-MAX1645A Maxim, MAX1645-MAX1645A Datasheet - Page 28

• Manufacturer Part Number: MAX1645-MAX1645A
• Description: Advanced Chemistry-Independent / Level 2 Battery Chargers with Input Current Limiting
• Manufacturer: Maxim

Advanced Chemistry-Independent, Level 2
Battery Chargers with Input Current Limiting
Figure 11. Typical System Using Multiple Smart Batteries
Table 8. Smart Battery Charger Type
by SMBus Mode and Charge Algorithm
Source
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.
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Slave only
Slave/Master
SMBus MODE
______________________________________________________________________________________
SYSTEM HOST
(SMBus HOST)
CHARGE ALGORITHM SOURCE
BATTERY
Level 2
Level 3
+12V, -12V
V
BATTERY DATA/STATUS REQUESTS
CC
CRITICAL EVENTS
SYSTEM
POWER
SUPPLY
SMART BATTERY 1
MODIFIED FROM
SMART BATTERY
SELECTOR
BATTERY
Level 3
Level 3
DC (UNREGULATED) / V
BATTERY
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.
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
SMART BATTERY 2
SMBus
NOTE: SB 1 POWERING SYSTEM
SB 2 CHARGING
Smart Battery Charger Types
SAFETY SIGNAL
V
SMBus
CHARGE
(UNREGULATED)
CONVERTER
MAX1645A
CHARGER
BATTERY
SMART
AC-DC
AC