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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