LTC1760CFW Linear Technology, LTC1760CFW Datasheet - Page 24

• Manufacturer Part Number: LTC1760CFW
• Description: IC MANAGER BATTERY DUAL 48TSSOP
• Manufacturer: Linear Technology

Specifications of LTC1760CFW

• Function: Charge Management
• Battery Type: Smart Batteries
• Voltage - Supply: 6 V ~ 28 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 48-TFSOP (0.240", 6.10mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

OPERATIO
LTC1760
2.6 LTC1760 SMBALERT Operation
The SMBALERT pin allows the LTC1760 to signal to the
SMBus Host that there has been a change of status.
This pin is asserted low whenever there is a change in
battery presence, AC presence or after a power on reset
event. This pin is cleared during an Alert Response or
any of the following reads:
BatterySystemState(),BatterySystemStateCont(),
BatterySystemInfo(), or LTC().
3 Charging Algorithm Overview
3.1 Wake-Up Charging Initiation
The following conditions must be met in order to allow
wake-up charging:
1. The battery thermistor must be COLD-RANGE, IDEAL-
RANGE, or UNDER-RANGE.
2. AC must be present.
3. BatterySystemStateCont(CHARGING_INHIBIT) must be
de-asserted (or low).
4. Hardware controlled charging inhibit must be
de-asserted (MODE not low with V
Wake-up charging initiates when a newly inserted battery
does not respond to any LTC1760 master read com-
mands. Only one battery will wake-up charge at a time.
When two batteries are inserted and both require wake-up
charging, Battery 1 will wake-up charge first. Battery 2 will
only wake-up charge when Battery 1 terminates wake-up
charging.
Wake-up charging takes priority over controlled charging;
this prevents one battery from tying up the charger when
it would be advantageous to dual charge two deeply
discharged batteries.
The LTC1760 will attempt to reinitiate wake-up
charging on both batteries after the SMBus Host asserts
BatterySystemStateCont(CHARGER_POR) or a power on
reset event. This will reset any wake-up charging safety
timers and is equivalent to removing and reinserting both
batteries.
The LTC1760 will attempt to reinitiate wake-up charging
on a battery if the battery is not being charged, the
24
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DDS
high).
thermistor is reporting IDEAL-RANGE, and the battery
fails to respond to an SMBus query. This is an important
feature for handling deeply discharged NiMh batteries.
These batteries may begin to talk while being charged and
go silent once charging has stopped.
Wake-up charging is disabled if the battery thermistor is
COLD-RANGE or UNDER-RANGE and the battery has been
charged for longer than t
3.2 Wake-Up Charging Termination
The LTC1760 will terminate wake-up charging when any of
the following conditions are met:
1. Battery removal (thermistor indicating OVER-RANGE)
2. AC is removed.
3. The SMBus Host issues a calibration request by setting
BatterySystemStateCont(CALIBRATE) high.
4. Any response to an LTC1760 master read of
ChargingCurrent(), Current(), ChargingVoltage(), or Volt-
age(). Note that the LTC1760 ignores all writes from the
battery.
5. Any of the following AlarmWarning() bits asserted high:
Note that the LTC1760 ignores all writes from the battery.
Each battery’s charge alarm is cached inside the LTC1760.
This bit will be set when any of the upper four bits of the
battery’s AlarmWarning() response are set. This bit will
remain set if a subsequent AlarmWarning() fails to re-
spond. The cached alarm will be cleared by any of the
following conditions.
OVER_CHARGED_ALARM
TERMINATE_CHARGE_ALARM
TERMINATE_CHARGE_RESERVED
OVER_TEMP_ALARM
a) Associated battery is removed.
b) A subsequent AlarmWarning() clears all
charge alarm bits for the associated battery.
c) A power on reset event.
d) The SMBus Host asserts
BatterySystemStateCont(CHARGER_POR) high.
TIMEOUT
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