ltc1760 Linear Technology Corporation, ltc1760 Datasheet - Page 16

• Manufacturer Part Number: ltc1760
• Description: Dual Smart Battery System Manager
• Manufacturer: Linear Technology Corporation

LTC1760
OPERATIO
2.3 Description of Supported SMBus Functions
The functions are described as follows:
Function Name() (command code)
Description:
A brief description of the function.
Purpose:
The purpose of the function, and an example where
appropriate.
SMBus Protocol: Refer to Section 2.5 and to the SMBus
specification for more details.
Input, Output or Input/Output: A description of the data
supplied to, or returned by, the function.
Whenever the LTC1760 encounters a valid command with
invalid data, it ACK’s the command, and ignores the invalid
data. For example, if an attempt is made to select battery
A and B to simultaneously communicate with the system
host, the LTC1760 will just ignore the request.
2.3.1 BatterySystemState() ('h01)
Description:
This function returns the present state of the LTC1760 and
allows access to individual batteries. The information is
broken into four nibbles that report:
The LTC1760 provides a mechanism to notify the system
whenever there is a change in its state. Specifically, the
LTC1760 provides the system with a notification when-
ever:
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Which battery is communicating with the SMBus Host
Which battery(s), if any, or AC is powering the system
Which battery(s) is connected to the Smart Charger
Which battery(s) is present.
• A battery is added or removed (Polling or SMBALERT).
• AC power is connected or disconnected (Polling or
• The LTC1760 autonomously changes the configura-
SMBALERT).
tion of the battery(s) supplying power (Polling only).
U
Purpose:
Used by the SMBus Host to determine the present state of
the LTC1760 and the attached batteries. It also may be
used to determine the state of the battery system after the
LTC1760 notifies the SMBus Host of a change via
SMBALERT.
SMBus Protocol: Read or Write Word.
Input/Output: word – Refer to “Section 2.2” for bit
mapping.
SMB_BAT[4:1]
The read/write SMB_BAT[4:1] nibble is used by the SMBus
Host to select with which individual battery to communi-
cate or to determine with which individual battery it is
communicating.
For example, an application that displays the remaining
capacity of all batteries would write to this nibble to
individually select each battery in turn and get its capacity.
Allowed values are:
To change this nibble, set only one of the lower two bits of
this nibble high. All other values will simply be ignored.
POWER_BY_BAT[4:1]
The read only POWER_BY_BAT[4:1] nibble is used by the
SMBus Host to determine which battery(s) is powering the
system. All writes to this nibble will be ignored.
Allowed values are:
• The LTC1760 autonomously changes the configura-
'b0010: SMBus Host is communicating with Battery 2.
'b0001: SMBus Host is communicating with Battery 1.
(Power On Reset Value)
'b0011: System being powered by Battery 2 and Battery
1 simultaneously.
'b0010: System being powered by Battery 2.
'b0001: System being powered by Battery 1.
'b0000: System being powered by AC.
tion of the battery(s) being charged (Polling only).
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