LTC1760 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1760' PDF : 44 Pages View PDF
LTC1760
OPERATION
0000b: Clears CALIBRATE_BAT1 and CALIBRATE_BAT2
and allows LTC1760 to chose. Power on reset default.
May not be updated if a calibration is in progress.
Option 2) SMBus Host allows LTC1760 to choose battery
to be calibrated.
BatterySystemStateCont(CALIBRATE_BAT[4:1]) = 0000b.
See previous option.
The LTC1760 determines that the battery requires
calibration by reading BatteryMode(CONDITION_FLAG).
This flag is cached in the LTC1760. The LTC1760 sets
BatterySystemStateCont(CALIBRATE_REQUEST) high.
The LTC1760 will always select the battery that is requesting
calibration. If both batteries are requesting calibration, the
LTC1760 will select Battery 1. If neither battery is request-
ing calibration, then calibration cannot occur.
5.2 Initiating Calibration of Selected Battery
The SMBus Host initiates a calibration by writing to
BatterySystemStateCont(CALIBRATE). Follow rules of the
previous section to preserve battery intended for calibra-
tion. The SMBus Host must only set the calibration bit
once per calibration.
The LTC1760 will discharge the selected battery as long as
the calibration is in progress (CALIBRATE high). Updates
to the cached BatteryMode(CONDITION_FLAG) will be
inhibited while CALIBRATE is asserted. This means that
discharge of the battery will continue even if the battery
clears the CONDITION_FLAG.
5.3 Terminating Calibration of Selected Battery
Calibration will end when CALIBRATE is cleared. CALI-
BRATE will be cleared when:
• AC is removed.
• The battery being calibrated is removed. When the
battery being calibrated is removed, the LTC1760
will automatically calibrate the other battery if it is
requesting calibration.
• BatterySystemStateCont(POWER_NOT_GOOD) is high.
• The battery sets Alarm Warning
(TERMINATE_DISCHARGE) high.
• The battery sets Alarm Warning
(FULLY_DISCHARGED) high.
• A zero is written to the CALIBRATE bit.
The LTC1760 will attempt to initiate a charge cycle after
the discharge cycle is completed.
6 MODE Pin Operation
The MODE pin is a multifunction pin that allows the LTC1760
to: 1) display charging status in stand alone operation;
2) activate hardware charge inhibit; 3) charge when SCL
and SDA are low and; 4) charge with an SMBus Host.
Summary of SDA, SCL and SMBALERT Operation as a Function
of MODE and VDDS Levels
CONDITION
LTC1760 OPERATING MODE
VMODE = GND
VVDDS < VIL_VDDS
SCL: Clock for Status Indicators
SCL: Clock for Status Indicators
SDA: Battery 2 Status
SMBALERT: Battery 1 Status
VMODE = GND SCL, SDA, SMBALERT: Normal Operation
VVDDS > VIH_VDDS LTC1760 Charging Inhibited
VMODE = VVCC2 SCL, SDA Ignored and May Float Low
VVDDS < VIL_VDDS SMBALERT: Normal Operation
SCL1, SDA1, SCL2 and SDA2: Normal Operation and
Charging is Allowed
VMODE = VVCC2 Normal Operation on all Pins, Charging is Allowed
VVDDS > VIH_VDDS
6.1 Standalone Charge Indication
When MODE is tied to GND and VVDDS < VIL_VDDS, the
function of SDA, SMBALERT, and SCL are changed as
described below:
SDA is an output and is used to monitor charging status
of Battery 2. Allowed values are:
Low: Battery 2 is charging.
High: Battery 2 not charging (AC is not present or bat-
tery is not present).
Blinking: Battery 2 charge complete (AC is present,
battery is present and not charging).
1760fa
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