LV51137T_11 Datasheet, PDF (6/8 Pages) Sanyo Semicon Device – 2-Cell Lithium-Ion Secondary Battery Protection IC

LV51137T
Excessive charger detection/release
If the voltage between V- pin and VSS pin becomes equal to or less than the excessive charger detection voltage by
connecting a charger, no charging can be made by turning the Cout pin “L” after delay time and turning off the
external Nch MOS FET. If that voltage returns to equal to or more than the excessive charger detection voltage
during detection delay time, the excessive charger detection will be stopped. If the voltage between V- pin and VSS
pin becomes equal to or more than the excessive charger detection voltage after excessive charger detection, the Cout
returns to “H” after delay time. The detection/return delay time is set internally.
If Dout pin is “L”, charging will be made through the parasitic diode of external Nch FET on Dout pin. In that case,
the voltage between V- pin and VSS pin is nearly -Vf which is less than the excessive-charger detection voltage,
therefore no excessive charger detection will be made during over-discharge, over-current and short-circuit detection.
Furthermore, if excessive voltage charger is connected to the over-discharged battery, no excessive charger detection
is made while the Dout pin is “L”. But the battery is continued charging through the parasitic diode. If the battery
voltage rises to the over-discharge detection voltage and the voltage between V- pin and VSS pin remains equal to or
less than the excessive charger detection voltage, the delay operation will be started after Dout pin turns to “H.”
0V cell charging operation
If voltage between VDD and V becomes equal to or more than the 0V cell charging lowest operation voltage when
the cell voltage is 0V, the Cout pin turns to “H” and charging is enabled.
Shorten the test time
By turning T pin to the VDD , the delay times set by the internal counter can be cut. If T pin is “open”, “L” the delay
times are normal. Delay time not set by the counter just like as short circuit detection delay cannot be controlled by
this pin.
In some circuit-board layout, an excessive current at the load short might cause this IC be in miss operation like as in
standby mode due to VSS line impedance. Therefore we recommend that the T pin is connected to the VSS pin.
Operation in case of detection overlap
Overlap state
Operation in case of
detection overlap
During over-charge
Over-discharge
Over-charge detection is preferred. If over-
detection
detection is made
discharge state continues even after over-
charge detection, over-discharge detection is
resumed.
State after detection
When over-charge state is made first, V- is
released. When over-discharge is detected after
over-charge state is made, the IC does not go
into the stand-by mode. Note that V- is
connected to VDD via 200kΩ.
Over-current
(*1) Both detections can be made in parallel.
(*2) When over-current state is made first, V- is
detection is made
Over-charge detection continues even when the connected to VSS via 15kΩ. When over-charge
over-current state is made first. If the over-
state is made first, V- is released.
charge state is made first, over-current detection
is interrupted.
During over-discharge Over-charge detection Over-discharge detection is interrupted and
The IC does not go into the stand-by mode
detection
is made
over-charge detection is preferred. When over-
discharge state continues even after over-
when over-discharge state is made after over-
charge detection. Note that V- is connected to
Over-current
charge state is made, over-discharge detection
is resumed.
(*3) Both detections can be made in parallel.
VDD via 200kΩ.
(*4) If over-current state is made first, V- will be
detection is made
Over-discharge detection continues even when
the over-current state is made first. But over-
connected to VSS via 15kΩ. If over-discharge
detection is made next, V- will be disconnected
During over-current
detection
current detection is interrupted when the over-
discharge state is made first.
Over-charge detection (*1)
is made
Over-discharge
(*3)
detection is made
from VSS and connected to VDD via 200kΩ to
get into stand-by mode. If over-discharge state
is made first, V- will be connected to VDD via
200kΩ to get into standby state.
(*2)
(*4)
(Note) Short-circuit detection can be made independently.
Excessive charger detection cannot be made during over-discharge, over-current and short-circuit detection.
And its delay time starts after the Dout pin returns to “H”.
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