AiT Semiconductor Inc.
A4002
www.ait-ic.com
BATTERY MANAGEMENT
ONE CELL LITHIUM-ION/POLYMER BATTERY PROTECTION IC
DETAILED INFORMATION
Functional Description
The A4002 the voltage and current of a battery and protects it from being damaged due to overcharge voltage,
overdischarge voltage, overdischarge current, and short circuit conditions by disconnecting the battery from
the load or charger. These functions are required in order to operate the battery cell within specified limits.
The device requires only one external capacitor. The MOSFET is integrated and its RSS(ON)is as low as 45mΩ
typical
Normal operating mode
If no exception condition is detected, charging and discharging can be carried out freely. This condition is
called the normal operating mode.
Overcharge Condition
When the battery voltage becomes higher than the overcharge detection voltage (VCU) during charging under
normal condition and the state continues for the overcharge detection delay time (tCU) or longer, the A4002
turns the charging control FET off to stop charging. This condition is called the overcharge condition. The
overcharge condition is released in the following two cases:
1.
When the battery voltage drops below the overcharge release voltage (VCL), the A4002 turns the
charging control FET on and returns to the normal condition.
2.
When a load is connected and discharging starts, the A4002 turns the charging control FET on and
returns to the normal condition. The release mechanism is as follows: the discharging current flows
through an internal parasitic diode of the charging FET immediately after a load is connected and
discharging starts, and the VM pin voltage increases about 0.7V(forward voltage of the diode) from the
GND pin voltage momentarily the A4002 detects this voltage and releases the overcharge condition.
Consequently, in the case that the battery voltage is equal to or lower than the overcharge detection
voltage (VCU), the A4002 returns to the normal condition immediately, but in the case the battery voltage
is higher than the overcharge detection voltage (VCU), the chip does not return to the normal condition
until the battery voltage drops below the overcharge detection voltage (VCU) even if the load is
connected. In addition. If the VM pin voltage is equal to or lower than the overcurrent 1 detection voltage
when a load is connected and discharging starts, load is connected and discharging starts, the chip
does not return to the normal condition
Remark If the battery is charged to a voltage higher than the overcharge detection voltage (VCU) and the
battery voltage does not drop below the overcharge detection voltage (VCU) even when a heavy load,
which causes an overcurrent, is connected, the overcurrent 1 and overcurrent 2 do not work until the
battery voltage drops below the overcharge detection voltage (VCU). Since an actual battery has,
REV1.0
- JUN 2018 RELEASED -
- 5 -
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