SS4035G Datasheet, PDF (1/11 Pages) Silicon Standard Corp. – Two-Cell Li-Ion and Li-Polymer Charge Management IC

SS4035G
Two-Cell Li-Ion and Li-Polymer Charge Management IC
PRODUCT SUMMARY
Charge management for two-cell Li-Ion or Li-Polymer battery packs
Individual cell monitoring - avoids over-charging
Pin-selectable charging current
Cell-balancing control circuit - maximizes pack useful life
FEATURES
Optional external thermistor monitors the pack temperature
Conditioning charging for reviving deeply discharged cells
Timer function available to limit the charging time
Pb-free, RoHS compliant SO-20 package
DESCRIPTION
The SS4035G is a charging control IC designed
for battery packs with two cells in series. When
multiple cells in a battery pack are connected in
series, the weakest cell determines the overall
pack capacity. The SS4035G has a cell-balance
control circuit to solve this problem, and monitors
the voltage of each cell to ensure that no cell is
over-charged. The pulse width modulation (PWM)
output can be used as either a linear or switching
charge-control circuit. Three digital input pins
determine the charge current. All these features
make the charging circuit design easy and flexible.
The SS4035G continuously monitors each cell
voltage, cell current and the battery temperature.
Any unspecified condition will stop the charging
to protect the battery cells. An external negative-
temperature-coefficient thermistor is used as a
sensor to monitor the battery pack temperature.
To be safe, charging is suspended if the voltage
of the temperature sense input pin is higher than
Min Temp Threshold (VTmin) or lower than Max
Temp Threshold (VTmax). When the battery
temperature is within the safe zone, the SS4035G
charges the battery in three phases: pre-charging,
constant-current, or constant-voltage. If the
voltage of the temperature sense input pin is higher
than Low Temp Threshold (Vtlow), or the battery
voltage is less than 3.1V, the SS4035G pre-charges
the battery with a low current.
After the precharging, the SS4035G applies a
constant current to the battery. The value of this
constant current is determined by the levels of
pins S1, S2 and S3 during power up. When
the battery voltage is above the threshold,
the SS4035G begins constant-voltage charging
until the battery is fully charged. The battery is
fully charged when the current drops down to
the termination threshold.
When the cell voltage is higher than the Balancing
Threshold (Vbal), the cell balancing circuit is
triggered if one cell voltage is higher than the
other by more than 0.02V.
1/09/2006 Rev.3.01
www.SiliconStandard.com
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