S-8241 Seiko Instruments, S-8241 Datasheet - Page 14

• Manufacturer Part Number: S-8241
• Description: Battery Protection IC for 1-Cell Pack
• Manufacturer: Seiko Instruments

Overcharge Condition
14
BATTERY PROTECTION IC FOR 1-CELL PACK
S-8241 Series
When the battery voltage becomes higher than the overcharge detection voltage (V
normal condition and the state continues for the overcharge detection delay time (t
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 (
and without overcharge hysteresis:
♦ Products with overcharge hysteresis (overcharge detection voltage (V
♦ Products without overcharge hysteresis (Overcharge detection voltage (V
Remark If the battery is charged to a voltage higher than the overcharge detection voltage (V
(V
Remark If the battery is charged to a voltage higher than the overcharge detection voltage (V
(V
CL
CL
When the battery voltage drops below the overcharge release voltage (V
charging control FET on and returns to the normal condition.
When a load is connected and discharging starts, the S-8241 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 0.7 V (Vf voltage of the diode) from the VSS
pin voltage momentarily. The IC detects this voltage (being higher than the overcurrent 1 detection
voltage) and releases the overcharge condition. Consequently, in the case that the battery voltage is
equal to or lower than the overcharge detection voltage (V
immediately, but in the case the battery voltage is higher than the overcharge detection voltage (V
the IC does not return to the normal condition until the battery voltage drops below the overcharge
detection voltage (V
lower than the overcurrent 1 detection voltage when a load is connected and discharging starts, the IC
does not return to the normal condition.
When the battery voltage drops below the overcharge release voltage (V
charging control FET on and returns to the normal condition.
))
))
When a load is connected and discharging starts, the S-8241 turns the charging control FET on and
returns to the normal condition. The release mechanism is explained 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 0.7 V (Vf voltage of the
diode) from the VSS pin voltage momentarily. Detecting this voltage (being higher than the
overcurrent 1 detection voltage), the IC increases the overcharge detection voltage about 50 mV, and
releases the overcharge condition. Consequently, when the battery voltage is equal to or lower than
the overcharge detection voltage (V
+ 50 mV, the S-8241 immediately returns to the normal condition. But the battery voltage is higher
than the overcharge detection voltage (V
condition until the battery voltage drops below the overcharge detection voltage (V
a load is connected. If the VM pin voltage is equal to or lower than the overcurrent 1 detection voltage
when a load is connected and discharging starts, the S-8241 does not return to the normal condition.
does not drop below the overcharge detection voltage (V
overcurrent, is connected, the overcurrent 1 and overcurrent 2 do not work until the battery voltage drops bellow
the overcharge detection voltage (V
of several dozens of mΩ, and the battery voltage drops immediately after a heavy load which causes an
overcurrent is connected, the overcurrent 1 and overcurrent 2 work. Detection of load short-circuiting works
regardless of the battery voltage.
does not drops below the overcharge detection voltage (V
overcurrent, is connected, the overcurrent 1 and overcurrent 2 do not work until the battery voltage drops
below the overcharge detection voltage (V
several dozens of mΩ, and the battery voltage drops immediately after a heavy load which causes an
overcurrent is connected, the overcurrent 1 and overcurrent 2 work. Detection of load short-circuiting works
regardless of the battery voltage.
CU
) even if the load is connected. In addition If the VM pin voltage is equal to or
Seiko Instruments Inc.
CU
CU
) + 50 mV. Since an actual battery has, however, an internal impedance
)
CU
CU
) + 50 mV, the S-8241 does not return to the normal
). Since an actual battery has, however, an internal impedance of
CU
) + 50 mV even when a heavy load, which causes an
CU
CU
), the IC returns to the normal condition
and
) even when a heavy load, which causes an
CU
) depending on the products with
) > overcharge release voltage
CU
) = Overcharge release voltage
CL
CL
), the S-8241 turns the
), the S-8241 turn the
CU
CU
) or longer, the S-8241
CU
) during charging under
CU
) and the battery voltage
) and the battery voltage
CU
) + 50 mV even if
Rev.4.1
CU
_01
),