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T63H0008A
Description of Operation
Normal condition
The T63H0008A monitors the voltage of the battery connected between VDD and VSS pin and the voltage
difference between V- and VSS pin to control charging and discharging. When the battery voltage is in the
range from the over -discharge detection voltage (VDET2) to the overcharge detection voltage (VDET1), and
the V- pin voltage is in the range from the charger detection voltage (VDET5) to the over-current 1 detection
voltage (VDET3), the IC turns both the charging and discharging control FETs on. This condition is called the
normal condition, and in this condition charging and discharging can be carried out freely.
Note:
When a battery is connected to the IC for the first time, the battery may not enter dischargeable state. In this case, set the
V- pin voltage equal to the VSS voltage or connect a charger to enter the normal condition.
Over-current condition (Detection of Over-current 1, Over-current 2, and Load short-circuiting)
When the condition in which V- pin voltage is equal to or higher than the over-current detection voltage,
condition which caused by the excess of discharging current over a specified value, continues longer than the
overcharge detection delay time in a battery under the normal condition, the T63H0008A turns the discharging
control FET off to stop discharging. This condition is called the over-current condition.
Though the V- and VSS pins are shorted by the RV-S resistor in the IC under the over-current condition,
the V- pin voltage is pulled to the VDD level by the load as long as the load is connected.
The V- pin voltage returns to V SS level when the load is released. The over-current condition returns to the
normal condition when the impedance between the EB+ and EB- pin becomes higher than the automatic
recoverable load resistance (see the equation [1] below), and the IC detects that the V- pin potential is lower
than the over-current 1 detection voltage (VDET3).
Note:
The automatic recoverable load resistance changes depending on the battery voltage and over-current 1detection voltage
settings.
Overcharge condition
When the battery voltage becomes higher than the overcharge detection voltage (VDD) during charging
under the normal condition and the detection continues for the overcharge detection delay time (tVDET1) or
longer, the T63H0008A turns the charging control FET off to stop charging. This condition is called the
overcharge condition. The overcharge condition is released by the following
two cases ((1) and (2)):
(1) When the battery voltage falls below the voltage difference, the overcharge detection voltage (VDET1) -
overcharge detection hysteresis voltage (VHC T1 ), the T63H0008A turns the charging control FET on and
turns to the normal condition.
(2) When a load is connected and discharging starts, the T63H0008A turns the charging control FET on and
returns to the normal condition. The mechanism is : just after the load is connected and discharging starts,
the discharging current flows through the parasitic diode in the charging control FET. At this moment V-
pin potential increases momentarily voltage of the parasitic diode from the VSS level When the V- pin
voltage goes higher than the over -current 1 detection voltage, and provided that the battery voltage goes
TM Technology, Inc. reserves the right
to change products or specifications without notice.
P. 10
Publication Date: Dec. 2003
Revision:A
TMT [ TAIWAN MEMORY TECHNOLOGY ]
