LTC4110
21
4110fb
OPERATION
be set to indicate calibration in progress. Soft-start ramps
the discharge current at a rate set by the capacitor on the
I
TH
pin (typically 10ms with 0.1μF capacitor). A limit to
how far the battery cell voltage will be discharged during
calibration can be programmed with the V
CAL
pin (Li-Ion
default = 2.75V/cell, lead acid default = 1.93V/cell, Smart
NiMH/NiCd default = 0.95V/cell). When the limit is reached
calibration is terminated, the CAL_COMPLETE bit in the
BBuStatus() register is set, the CAL_ON bit in the BBuS-
tatus() register will be cleared and the charge mode is
automatically entered to begin recharging the battery. If
the GPIO3 is confi gured as a calibration complete status
output (CAL_COMPLETEb), it will be forced low until reset
by the CAL_RESET write bit. Calibration is inhibited during
backup or shutdown modes. Calibration is also inhibited
when a thermistor is sensed absent.
During calibration, user-programmable supply back-drive
protections are provided. These protections prevent a
reversal of current into the main supply and/or possibly
raising the supply voltage to unsafe levels should the
Figure 5. SLA Charge State Diagram (Does Not Include Calibration)
4110 F05
PWM
STOPPED
(BATTERY OVP)
STOP
(OVERTEMPERATURE)
ANY
CHARGE
STATE
RESUME
CHARGE
STATE
8
6
7
5
3
1
9
ANY
CHARGE
STATE
4
RESET
STOP
2
CHARGE
#
Logic Event (T = True, F = False) [Notes]
Notes and/or Actions (T = True, F = False)
1
RES_OR = F & DCDIV pin = T & SHDN pin = F & CHARGE_INHIBITED = F &
CHG_FLT = F
I
CHG
= On & CHG = T
2
Or
V
AR
= T [AutoRestart]
ChargingVoltage() & ChargingCurrent() ≠ 0 sent
ALARM_INHIBITED = F
3
Or
Or
ChargingVoltage() or ChargingCurrent() = 0 sent
RESET_TO_ZERO = T [See ChargeMode()]
CHARGE_INHIBIT = T [See ChargeMode()]
I
CHG
= Off & CHG = F
4
Or
Or
Or
Or
DCDIV pin = F
RES_OR = T [Bat Removed, See ChargeStatus()]
SHDN pin = T
V
UVD
= T
POR_RESET = T [See ChargeMode()]
I
CHG
= Off & CHG = F & CHARGE_INHIBITED = F &
ALARM_INHIBITED = F
5
RES_HOT = T & RES_UR = F [See ChargeStatus()]
I
CHG
= Off & CHG_FLT = T
6
RES_HOT = F [See ChargeStatus()]
I
CHG
= On & CHG_FLT = F
7
V
BOV
= T
PWM stopped. Timers remain running.
8
V
BOV
= F
PWM restarted.
9
Or
Or
Or
AlarmWarning() command is sent by Smart Battery over SMBus with any of
the following bits set to True:
OVER_CHARGED_ALARM
TERMINATE_CHARGE_ALARM
Reserved ALARM
OVER_TEMPERATURE_ALARM
I
CHG
= Off & CHG = F & ALARM_INHIBITED = T
(ALARM_INHIBITED bit is found in ChargeStatus())
Note: For all charge states, V
CHG
is always active
