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12-07-0005

PT0268-1

07/05/12

8

PT8A2707-12/17-19

Charger Controller

with Fuel-Guage & LCD/LED Display

a)

If the motor is turned on during the pre-charge state, obviously there is no charging current to battery. The PT8A2707-

12/2717-19 will return to discharging mode while fuel-gauge is continuing to count the discharge amount. The

discharging is stopped at the same criteria described in the Discharging Mechanism section.

b)

If the motor is turned on during the fast-charge state, the fast-charge safety timer is held. If the motor is turned on less

than 5% of the battery maximum capacity, fast-charge resumes with fast-charge timer continue to count (but start-up

timer starts from beginning). However, when the motor is accumulatively turned on over 5% of the battery maximum

capacity while cord is still connected, the fast-charge timer is cleared and the battery pack will be recharged from pre-

charge state again once motor is off.

c)

If the motor is turned on during the trickle-charge state, if the motor is turned on to accumulatively consume less than

5% (not necessarily in single operation) of the battery maximum capacity, the PT8A2707-12/2717-19 resumes trickle-

charge state. However, when the motor is turned on over 5% of the battery maximum capacity during the trickle-charge

state, the battery pack will be recharged from pre-charge state again after motor is off.

Besides, at any time when the battery pack voltage is lower than the No-Power value or discharging current is higher than the

preset limit levels for 3sec, the motor will be stopped and the devices return to charging status.

2)

The motor is turned on but draws less current than the AC/DC adapter can supply: In all cases, when the battery is not

discharged, the PT8A2707-12/2717-19 regulates a charging current of 1/10 of the fast-charge current to battery pack. In this

case, the battery pack is under slow charging. Similarly, there are three more situations to observe:

a)

If the motor is turned on during the pre-charge state, once motor is turned off, the PT8A2707-12/2717-19 will resume

back to the pre-charge state.

b)

If the motor is turned on during the fast-charge state, the fast-charge timer is held until motor is turned off to resume

fast-charging.

c)

If the motor is turned on during the trikle-charge state, once motor is turned off, the PT8A2707-12/2717-19 will resume

back to the maintenance state.

In any charging states, if the battery temperature is measured higher than 55C, the motor is stopped and the 0.1C charging current

is cut off. The LED/LCD still displays as in “Charging Mode”. The motor will draw current from battery pack until the battery

temperature is below 55C to resume 0.1C charging current. However, no matter whether it is in fast-charging or trickle-charging

modes, when the motor is turned on to consume over 5% (accumulatively, not necessarily in single operation) of the battery

maximum capacity during battery is over-temperature, the battery pack will be recharged from pre-charge state again after motor

is off.

5.

Fuel-Gauge Counter

1)

Charge Counting: Charge activity is detected based on positive voltage difference (VFUEL) between the pins ISENFG and

ISENCOM. When voltage of ISENFG is higher than the voltage of ISENCOM, the PT8A2707-12/2717-19 increments its

fuel-gauge counter at a rate proportional to VFUEL. VFUEL is sampled and converted into digital data through high-

precision A/D converter. When the fuel-gauge counter accumulates up to 99% level but none of the full-charge criteria (-V,

dT/dt, safety timer, maximum battery voltage) is detected, the fuel-gauge will wait at 99% level. Right after the battery is

fully-charged, the PT8A2707-12/2717-19 displays full-charge and learns the capacity of the battery pack such that the display

will be more and more accurate in both charging and discharging cycles later.

2)

Discharge Counting: Discharge activity is detected based on a negative voltage difference (VFUEL) between the pins

ISENFG and ISENCOM. When voltage of ISENFG is lower than the voltage of ISENCOM, the PT8A2707-12/2717-19

decrements its fuel-gauge counter at a rate proportional to VFUEL. VFUEL is sampled and converted into digital data

through high-precision A/D converter. In case the fuel-gauge counter rolls to zero count while the battery voltage is still

higher than the preset No-Power level, the Battery-Low LED is still flashing while user can still use motor. Motor will be

stopped when battery voltage is below the No-Power level. The maximum fuel value is not updated, but will be updated when

necessary for next time the battery is fully charged. The fuel value will be adjusted to 10% if the battery voltage gradually

falls below Battery-Low threshold.

6.

Idle Mode

1)

Standby: When cord is not connected and motor is off, the PT8A2707-12/2717-19 turn to idle state to save power. Some

internal circuits are shut-down to keep the standby power at about 20A.

2)

Background Offset Cancellation: when the PT8A2707-12/2717-19 is waked up by user, an offset cancellation is performed

for the internal precise A/D converter before entering cord or motor modes. It normally takes 0.2~0.3s. The PT8A2707-

12/2717-19 returns to idle state after use.