Sony Ericsson GR64 Manuel D’Utilisation
LZT 123 1834
43
As a safety precaution, the battery cell voltage must be at least 2.5 V before fast-
charge is allowed to take place. If the battery cell voltage is less than 2.5 V, it is
considered either deeply discharged or shorted. To protect a Li-ion cell from the
damage that may occur if it is fast-charged from this state, a 3.6 V trickle-charge
source is used to safely condition the battery cell. The conditioning charge current is
limited to 50 mA, which for most Li-ion cells is 10% or less of the recommended CC
fast-charge current. In most instances, the battery cell voltage will be greater than
2.5 V at the time the charge request is initiated, resulting in the conditioning phase
being skipped.
charge is allowed to take place. If the battery cell voltage is less than 2.5 V, it is
considered either deeply discharged or shorted. To protect a Li-ion cell from the
damage that may occur if it is fast-charged from this state, a 3.6 V trickle-charge
source is used to safely condition the battery cell. The conditioning charge current is
limited to 50 mA, which for most Li-ion cells is 10% or less of the recommended CC
fast-charge current. In most instances, the battery cell voltage will be greater than
2.5 V at the time the charge request is initiated, resulting in the conditioning phase
being skipped.
There is always a small chance that the charge management block in
the GR64 power management ASIC will malfunction or fail, which
could lead to over-charging of the battery. It is strongly
recommended that any battery chosen for use with your application
has its own additional integrated over-current and over-voltage
protection.
the GR64 power management ASIC will malfunction or fail, which
could lead to over-charging of the battery. It is strongly
recommended that any battery chosen for use with your application
has its own additional integrated over-current and over-voltage
protection.
5.7.2 Series Diode
When charging is disabled, the potential for rapid cell discharge through the body
diode inherent in the Enhancement-mode charging FET, a Schottky diode must be
placed in between the external source and the CHG_IN pin. The diode should have a
forward current and power dissipation rating consistent with its intended use, and a
maximum forward voltage drop of 0.6V.
diode inherent in the Enhancement-mode charging FET, a Schottky diode must be
placed in between the external source and the CHG_IN pin. The diode should have a
forward current and power dissipation rating consistent with its intended use, and a
maximum forward voltage drop of 0.6V.
5.7.3 Battery Selection
Whilst there are several rechargeable battery technologies commercially available,
including Nickel Cadmium (NiCd), Nickel Metal Hydride (Ni-MH), Lithium-Polymer (Li-
Polymer) and Lithium-Ion (Li-Ion), the only technology recommended and supported
for use with the GS64 is Li-Ion. Li-Ion provides a good combination of high energy
(3.7v) and long cycle life, which lead to low overall energy cost.
including Nickel Cadmium (NiCd), Nickel Metal Hydride (Ni-MH), Lithium-Polymer (Li-
Polymer) and Lithium-Ion (Li-Ion), the only technology recommended and supported
for use with the GS64 is Li-Ion. Li-Ion provides a good combination of high energy
(3.7v) and long cycle life, which lead to low overall energy cost.
The weight of lithium ion batteries is approximately one half compared with a nickel
cadmium or nickel metal hydride battery of similar capacity. The volume of lithium
ion batteries is 40 to 50% smaller than that of nickel cadmium, and 20 to 30% smaller
than that of a nickel metal hydride.
cadmium or nickel metal hydride battery of similar capacity. The volume of lithium
ion batteries is 40 to 50% smaller than that of nickel cadmium, and 20 to 30% smaller
than that of a nickel metal hydride.
The lithium ion battery is free from the so-called memory effect, a phenomenon
associated with nickel cadmium in which the apparent battery capacity decreases
when shallow charge and discharge cycles are repeated.
associated with nickel cadmium in which the apparent battery capacity decreases
when shallow charge and discharge cycles are repeated.
A single lithium ion cell has a voltage of 3.7V (mean value), which is equal to either
three nickel cadmium or nickel-metal hydride cells connected in series. This voltage
is close to the nominal VCC of the GR64 device.
three nickel cadmium or nickel-metal hydride cells connected in series. This voltage
is close to the nominal VCC of the GR64 device.
CAUTION