NE57611BDH Philipss, NE57611BDH Datasheet - Page 6

• Manufacturer Part Number: NE57611BDH
• Description: Single cell Li-ion battery charger
• Manufacturer: Philipss

Philips Semiconductors
Charging Lithium cells
The lithium cells must be charged with a dedicated charging IC such
as the NE57600. These dedicated charging ICs perform a
current-limited, constant-voltage charge, as shown in Figure 4.
2003 Oct 15
Single cell Li-ion battery charger
1.0
0.5
4.0
3.0
V
OV
Figure 4. Lithium cell charging curves.
CONSTANT
CURRENT
TIME (HOURS)
TIME (HOURS)
1.0
1.0
Point B
CONSTANT
VOLTAGE
2.0
2.0
SL01663
6
overdischarged voltage level, then the cell is too damaged to charge
The charger IC begins charging with a current that is typically the
rating of the cell (1C) or the milliampere rating of the cell. As the cell
approaches its full-charge voltage rating (V
the cell decreases, and the charger IC provides a constant voltage.
When the charge current falls below a preset amount, 50 mA for
example, the charge is discontinued.
If charging is begun below the overdischarged voltage rating of the
cell, it is important to slowly raise the cell voltage up to this
overdischarged voltage level. This is done by a reconditioning
charge. A small amount of current is provided to the cell (50 mA for
example), and the cell voltage is allowed a period of time to rise to
the overdischarged voltage. If the cell voltage recovers, then a
normal charging sequence can begin. If the cell does not reach the
and the charge is discontinued.
To take advantage of the larger energy density of lithium cells it is
important to allow enough time to completely charge the cell. When
the charger switches from constant current to constant voltage
charge (Point B, Figure 4) the cell only contains about 80 percent of
its full capacity. When the cell is 100 mV less than its full rated
charge voltage the capacity contained within the cell is 95 percent.
Allowing the cell to slowly complete its charge takes advantage of
the larger capacity of the lithium cells.
OV
), the current entering
NE57611
Product data