Lithium-ion battery charger design requirements
Effect
of lithium ion battery safety and effective charging voltage, current and
temperature, so chargers to take care of a good control in the design of these
three factors.
In
accordance with the above request, the charger IC active power path management,
the power path management requirements in the load the load current/under
unloaded conditions, real time adjustment of lithium-ion battery charging
current, effective supervision and management in accordance with USB-IF current
limit and soft activation function required by the specification. IC
integration within the temperature monitoring function, if IC temperature
exceeds the limit value, automatically reduces the charge current. Charger
power adapter ensure that 5V DC power supply can charge pressure steady flow,
if one has a current, maximum charging current can be set with an external
resistor control to avoid USB overload.
Charger
also has captive power path management capabilities, when system-side
electricity when they exceed the input power supplies constraints; ensure the
initiative to activate the discharge function of lithium-ion batteries, while
system-side needed to supply its power. Charger consumes minimal battery is
lower than 3V, IC inside to set the charging current should be 10% preset
current.
Suitable
temperature for charging li ion battery are 0~45℃,If the 0.5℃ charging, you can
1℃
Temperature rise as 90℃, charger
operates on 35℃
environment temperature, best for lithium batteries, so 2 hour
rate charged the current best.
The
fundamental problem is that when charging when the charging temperature is too
high, therefore, the design must balance between charge current and thermal
bodies, due to the portable charger portable products that apply to light. Use
the low thermal conductivity of the plastic casing, regardless of the metal
fins, finally, reduce the charging current or prolong the charging time of a
way to achieve lower operating temperature.
Therefore,
the general lithium-ion battery charger for 1500mAh following capacity lithium
battery, and for high-voltage, high-capacity lithium-ion battery, you use
synchronous switching charger.
After
the design of lithium-ion battery charger charging process is divided into
three phases:
1.And
charging IC to detect whether there is a short circuit or output overload
protection mode, such as normal, and then see if battery voltage is 3V , Above
3V Constant current charging direct access below 3V , Then the constant-current
10% the pre charge current;
2.
Fast, constant-current charge State: height up to 4.2V;
3.And
constant pressure stage: batteries up to 4.2V, voltage no longer increase
charge current showed a declining trend until it reaches a constant current of
10% Stop charging.
Future
lithium battery charger will provide faster, safer and more comprehensive
charging management system.
Contact:
Person:
Tim.lee
Company:
Dongguan Large Electronics Co., Ltd
Add:
Block A, Gaosheng Technology Zone, Nancheng District, Dongguan City, Guangdong
Province, CN
Tel:
86-769-23182621
Email:
Tim.lee@largepower.cn
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