lv51138t Sanyo Semiconductor Corporation, lv51138t Datasheet - Page 5

• Manufacturer Part Number: lv51138t
• Description: 2-cell Lithium-ion Secondary Battery Protection Ic
• Manufacturer: Sanyo Semiconductor Corporation

Functional Description
Over-charge detection
Over-charge release
Over-discharge detection
Over-discharge release
Over-current detection
Short circuit detection
Over-current/short-detection release
If either of the cell voltage is equal to or more than the over-charge detection voltage, stop further charging by
turning “L” the Cout pin and turning off external Nch MOS FET after the over-charge detection delay time. This
delay time is set by the internal counter.
The over-charge detection comparator has the hysteresis function. Note that this hysteresis can be cancelled by
connecting the load after detection of over-charge detection. and it becomes small to hysteresis peculiar to a
comparator.
If both cell voltages become equal to or less than the over-charge release voltage (VM ≤ Vd3) when charger is
connected, or if it become equal to or less than the over-charge release voltage (VM > Vd3) when load is connected,
the Cout pin returns to “H” after the over-charge release delay time set by the internal counter.
When load is connected and either cell or both cell voltages are equal to or more than the over-charge release voltage
(VM > Vd3), the Cout pin does not return to “H”. But the load current flows through the parasitic diode of external
Nch MOS FET on Cout, consequently each cell voltage becomes equal to or less than over-charge release voltage,
(VM > Vd3) the Cout pin returns to “H.” after the over-charge release delay time.
excessive charger detection starts after over-charge release operation.
When either cell voltage is equal to or less than over-discharge voltage, the IC stops further discharging by turning
the Dout pin “L” and turning off external Nch MOS FET after the over-charge detection delay time.
The IC goes into stand-by mode after detecting over-discharge and its consumption current is kept at about 0A. After
over-discharge detection, the V - pin will be connected to V DD pin via internal resistor (typ 200kΩ).
Release from over-discharge is made by only connecting charger. If the V - pin voltage becomes equal to or lower
than the stand-by release voltage by connecting charger after detecting over-discharge, The IC is released from the
stand-by state to start cell voltage monitoring. If both cell voltages become equal to or more than the over-discharge
detection voltage by charging, the Dout pin returns to “H” after the over-discharge release delay time set by the
internal counter.
When excessive current flows through the battery, the V - pin voltage rises by the ON resister of external MOS FET
and becomes equal to or more than the over-current detection voltage, the Dout pin turns to “L” after the over-current
detection delay time and the external Nch MOS FET is turned off to prevent excessive current in the circuit. The
detection delay time is set by the internal counter. After detection, the V - pin will be connected to V SS via internal
resistor (typ 30kΩ). It will not go into stand-by mode after detecting over-current.
If greater discharging current flows through the battery and the V - pin voltage becomes equal to or more than the
short-circuit detection voltage, it will go into short-circuit detection state after the short circuit delay time shorter than
the over-current detection delay time. When short-circuit is detected, just like the time of over-current detection, the
Dout pin turns to “L” and external Nch MOS FET is turned off to prevent high current in the circuit. The V - pin will
be connected to V SS after detection via internal resistor (typ. 30kΩ). It will not go into stand-by mode after detecting
short circuit.
After detecting over-current or short circuit, the internal resistor (typ. 30kΩ) between V - pin and V SS pin becomes
effective. If the load resistor is removed, the V - pin voltage will be pulled down to the V SS level. Thereafter, the IC
will be released from the over-current/short-circuit detection state when the V - pin voltage becomes equal to or less
than the over-current detection voltage, and the Dout pin returns to “H” after over-current release delay time set by
the internal counter.
However, excessive voltage charger is connected as mentioned below, Cout pin does not return to “H” because
LV51138T
No.A1151-5/8