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LTC4110

4110fa

SMBUS WAKE-UP CHARGE STATE

The battery will be charged with a ﬁxed “wake-up” current

regardless of previous ChargingCurrent() and Charging-

Voltage() register values during wake-up charging. The cur-

rent is identical to the preconditioning charge current which

is programmed with an external resistor through the IPCC

pin. The wake-up timer has the same period as tTIMEOUT,

typically 175sec (see tTIMEOUT).

The following conditions must be met to allow wake-up

charge of the battery:

• The SafetySignal must be RES_COLD, RES_IDEAL, or

RES_UR.

• AC must be present. This is qualiﬁed by DCDIV > VAC

+ VACH and DCIN above UVLO.

• Wake-up charge initiates if a battery does not write

non-zero values to ChargingCurrent() and Chargin-

Voltage() registers when AC power is applied and a

battery is present or when AC is present and a battery

is subsequently connected.

The following conditions will terminate the wake-up charge

state and end charge attempts, unless otherwise noted.

• The tTIMEOUT period is reached (see tTIMEOUT) when

the SafetySignal is RES_COLD or RES_UR. The state

machine will go to the SMBus OFF state. The CHG_FLT

bit is not set.

• The SafetySignal is registering RES_HOT. The state

machine will go to the SMBus OFF state.

• The SafetySignal is registering RES_OR. The state

machine will go to the reset state.

• The LTC4110 will leave the wake-up charge state and

go into the SMBus preconditioning charge state if the

ChargingCurrent() AND ChargingVoltage() registers

have been written to non-zero values.

• The AC power is no longer present (DCDIV < VAC or

DCIN below UVLO). The state machine will go to the

reset state.

• The ALARM_INHIBITED becomes set in the

ChargerStatus() register. The state machine will go to

the SMBus OFF state.

• CHARGE_INHIBIT is set in the BBuControl() register.

Charge is stopped, however, the wake-up timer is not

paused. Clearing CHARGE_INHIBIT will enable the

LTC4110 to resume charging.

• There is insufﬁcient DCIN voltage to charge the battery

as determined by the internal UVLO. This causes the

state machine to enter the reset state and stop all charge

activity.TheLTC4110willresumewake-upchargingwhen

there is sufﬁcient DCIN voltage to charge the battery.

• The CAL_START bit in the BBuControl() register is set.

Charge is stopped and the LTC4110 enters the calibra-

tion state.

• Writing a zero value to either the ChargingVoltage() or

ChargingCurrent() register. The state machine will go

to the SMBus OFF state.

• RESET_TO_ZERO is set in the BBuControl() register.

Charge is stopped; the SMBus OFF State is entered.

SMBUS PRECONDITIONING CHARGE STATE

During the SMBus preconditioning charge state, the charger

will be operating in the preconditioning charge current

limit. The following conditions must be met in order to

allow SMBus preconditioning charge to start:

• The ChargingVoltage() AND ChargingCurrent() registers

must be written to non-zero values. The LTC4110 will

not directly report the status of these registers. The

battery needs only write one pair of ChargingVoltage()

and ChargingCurrent() registers to stay in this state. The

tTIMEOUT timerisnotoperationalinSMBusprecondition-

ing charge state.

• The SafetySignal must be RES_COLD, RES_IDEAL, or

RES_UR.

• AC must be present and sufﬁcient. This is qualiﬁed by

DCDIV > VAC + VACH and DCIN > UVLO.

The following conditions will affect the SMBus precondi-

tioning charge state as speciﬁed below:

•

The SafetySignal is registering RES_HOT. Charge is

stopped; the SMBus OFF state is entered.

OPERATION

LTC4110 Datasheet(PDF) 18 Page - Linear Technology

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