LTC1760
18
1760fc
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CHARGE_BAT[4:1] Nibble
The read only CHARGE_BAT[4:1]nibble is used by the
SMBus Host to determine which, if any, battery is being
charged. All writes to this nibble will be ignored.
Allowed values are:
0011b: Both Battery 2 and Battery 1 being charged.
0010b: Only Battery 2 is being charged.
0001b: Only Battery 1 is being charged.
0000b: No battery being charged.
An indication that multiple batteries are being charged
simultaneously does not indicate that the batteries are
being charged at the same rate or that they will complete
their charge at the same time. To actually determine
when an individual battery will be fully charged, use the
SMB_BAT[4:1] nibble to individually select the battery of
interest and read the TimeToFull() value.
PRESENT_BAT[4:1] Nibble
The read only PRESENT_BAT[4:1]nibble is used by the
SMBus Host to determine how many and which batteries
are present. All writes to this nibble will be ignored.
Allowed values are:
0011b: Both Battery 2 and Battery 1 are present.
0010b: Only Battery 2 is present.
0001b: Only Battery 1 is present.
0000b: No batteries are present.
2.3.2 BatterySystemStateCont() (0
×
02)
Description:
This function returns additional state information of the
LTC1760 and provides a mechanism to prohibit charging.
This command also removes any requirement for the
SMBus Host to communicate directly with the charger to
obtain AC presence information. When the LTC1760 is used,
access to the charger 8-bit address, 0
×
012, is blocked.
Purpose:
Used by the SMBus Host to retrieve additional state
information from the LTC1760 and the overall system
power configuration. It may also be used by the system
to prohibit any battery charging.
SMBus Protocol:
Read or Write Word.
Input/Output:
word - Refer to “Section 2.2” for bit
mapping
AC_PRESENT Bit
The read only AC_PRESENT bit is used to show the user
the status of AC availability to power the system. It may
be used internally by the SMBus Host in conjunction with
other information to determine when it is appropriate to
allow a battery conditioning cycle. Whenever there is a
change in the AC status, the LTC1760 asserts
SMBALERT
low. In response, the system has to read this register to
determine the actual presence of AC. The LTC1760 uses
the DCDIV pin to measure the presence of AC.
Allowed values are:
1b: The LTC1760 has determined that AC is present.
0b: The LTC1760 has determined that AC is not pres-
ent.
POWER_NOT_GOOD Bit
The read only POWER_NOT_GOOD bit is used to show
that the voltage delivered to the system load is inadequate.
This is determined by the LOPWR comparator.
The POWER_NOT_GOOD bit will also be set if the LTC1760
has detected a short circuit condition (see “Section 8.2”)
or an emergency turn-off condition (see “Section 8.3”).
Under either of these conditions the power paths will be
shut off even if battery or DC power is available.
Allowed values are:
1b: The LTC1760 has determined that the voltage
delivered to the system load is inadequate.
0b: The LTC1760 has determined that the voltage
delivered to the system load is adequate.
CALIBRATE_REQUEST_SUPPORT Bit
The read only CALIBRATE_REQUEST_SUPPORT bit is
always set high to indicate that the LTC1760 has a mecha-
nism to determine when any of the attached batteries are
in need of a calibration cycle.
OPERATION
