EUP9261
Overdischarge condition
Abnormal charge current detection is released when
the voltage difference between VM pin and VSS pin
becomes less than charger detection voltage (VCHA).
When the battery voltage falls below the
overdischarge detection voltage (VDL) during
discharging under the normal condition and the
detection continues for the overdischarge detection
delay time (tDL) or longer, the EUP9261 turns the
discharging control FET off to stop discharging. This
condition is called the overdischarge condition. When
the discharging control FET turns off, the VM pin
voltage is pulled up by the RVMD resistor between VM
and VDD in the IC. The voltage difference between
VM and VDD then falls bellow 1.3V (typ.), the current
consumption is reduced to the power-down current
consumption (IPDN). This condition is called the
power-down condition. The power-down condition is
released when a charger is connected and the
voltage difference between VM and VDD becomes
1.3V (typ.) or higher. Moreover when the battery
voltage becomes the overdischarge detection voltage
(VDL) or higher, the EUP9261 turns the discharging
FET on and returns to the normal condition.
Delay circuits
The detection delay times are generated by dividing the
approximate 3.5 KHz clock with a counter.
Note1:
The detection delay time for overcurrent 2 and load
short-circuiting start when the overcurrent 1 is detected.
As soon as the overcurrent 2 or load short-circuiting is
detected over the detection delay time for overcurrent 2
or load short-circuiting after the detection of
Overcurrent 1, the EUP9261 turns the discharging
control FET off.
Charger detection
When a battery in the overdischarge condition is
connected to a charger and provided that the VM pin
voltage is lower than the charger detection voltage
(VCHA), the EUP9261 releases the overdischarge
condition and turns the discharging control FET on as
the battery voltage becomes equal to or higher than the
overdischarge detection voltage (VDL) since the charger
detection function works. This action is called charger
detection. When a battery in the overdischarge
condition is connected to a charger and provided that
the VM pin voltage is not lower than the charger
detection voltage (VCHA), the EUP9261 releases the
Overdischarge condition when the battery voltage
reaches the overdischarge detection voltage (VDL)
overdischarge hysteresis (VHD) or higher.
Figure17.
Note2:
When the overcurrent is detected and it continues for
longer than the Overdischarge detection delay time
without releasing the load, the load, the condition
changes to the power-down condition when the
battery voltage falls below the Overdischarge
detection voltage.
Abnormal charge current detection
Note3:
If the VM pin voltage falls below the charger detection
voltage (VCHA) during charging under normal condition
and it continues for the overcharge detection delay time
(tCU) or longer, the charging control. FET turns off and
charging stops. This action is called the abnormal
charge current detection. Abnormal charge current
detection works when the DO pin voltage is “H” and the
VM pin voltage falls below the charger detection
voltage (VCHA). Consequently, if an abnormal charge
current flows to an over-discharged battery, the
EUP9261 turns the charging control FET off and stops
charging after the battery voltage becomes higher than
the overdischarge detection voltage which make the
DO pin voltage “H”, and still after the overcharge
detection delay time (tCU) elapses.
When the battery voltage falls below the
Overdischarge detection voltage due to the
overcurrent, the EUP9261 turns the discharging
control FET off by the overcurrent detection. And in
this case the recovery of the battery voltage is so
slow that the battery voltage after the Overdischarge
detection delay time is still lower than the
Overdischarge detection voltage, the EUP9261
transits to the power-down condition.
DS9261 Ver2.4 Jan. 2007
18
EUTECH [ EUTECH MICROELECTRONICS INC ]
