MAX1667 Datasheet, PDF (10/28 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
SYSTEM
POWER
CONTROL
AC
SYSTEM HOST
(SMBus HOST)
V_BATTERY
DC (UNREGULATED)
AC-DC
CONVERTER
(UNREGULATED)
SMART BATTERY
SAFETY
SIGNAL
MAX1667
SMART BATTERY
CHARGER
CRITICAL EVENTS
BATTERY DATA/STATUS REQUESTS
CHARGING VOLTAGE/CURRENT
REQUESTS
CRITICAL EVENTS
SMBus
Figure 3. Typical Single Smart Battery System
Smart Battery Charging System
A smart battery charging system, at a minimum, con-
sists of a smart battery and smart battery charger com-
patible with the Smart Battery System specifications
using Intel’s system management bus (SMBus).
tery’s positive and negative terminals), SMBus (clock
and data), and safety signal (resistance, typically tem-
perature dependent). Additionally, the system host
must be able to query any battery in the system so it
can display the state of all batteries present in the sys-
tem.
Smart Battery System Block Diagrams
A system may use one or more smart batteries. The
block diagram of a smart battery charging system
shown in Figure 3 depicts a single battery system. This
is typically found in notebook computers, video cam-
eras, cellular phones, and other portable electronic
equipment.
Another possibility is a system that uses two or more
smart batteries. A block diagram for a system featuring
multiple batteries is shown in Figure 4. The smart bat-
tery selector is used to connect batteries to either the
smart battery charger or the system, or to disconnect
them, as appropriate. For a standard smart battery, the
following connections must be made: power (the bat-
Figure 4 shows a two-battery system where Battery 2 is
being charged while Battery 1 is powering the system.
This configuration may be used to “condition” Battery
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 in
whether they modify the charging algorithm of the
smart battery as shown in Table 1. Level 3 smart bat-
tery chargers are supersets of Level 2 chargers and as
such support all Level 2 charger commands.
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