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LTC1760

1760f

5 Battery Calibration (Conditioning)

Calibration allows the SMBus Host to fully discharge a

battery for conditioning purposes. The SMBus Host may

determine the battery to be discharged or allow the

LTC1760 to choose based on the batteries’ request to be

conditioned.

5.1 Selecting a Battery to be Calibrated

Option 1) SMBus Host chooses battery to be calibrated

using BatterySystemStateCont(CALIBRATE_BAT[4:1])

Allowed values:

'b0001: Set CALIBRATE_BAT1. Only has an effect if

Battery 1 BatteryMode(CONDITION_FLAG) is high .

May not be updated if a calibration is in progress.

'b0010: Set CALIBRATE_BAT2. Only has an effect if

Battery 2 BatteryMode(CONDITION_FLAG) is high.

May not be updated if a calibration is in progress.

'b0000: 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]) = 'b0000.

See previous option.

The LTC1760 determines that the battery requires calibra-

tion 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 request-

ing calibration. If both batteries are requesting calibration,

the LTC1760 will select Battery 1. If neither battery is

requesting calibration, then calibration cannot occur.

OPERATIO

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.

LTC1760CFW Datasheet(PDF) 28 Page - Linear Technology

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