How Do I Choose the Best USB Battery Charger?

The battery charger chip is a chip that can charge a variety of batteries. It can charge a single lithium battery, a single lithium iron phosphate battery, or two to four nickel-metal hydride batteries.

Battery charger chip

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battery charger

Can use USB interface or AC adapter to charge the battery On-chip power transistor Constant current charging termination voltage accuracy 1% Integrated 8-bit analog-digital conversion circuit inside, can automatically adjust the charging current according to the current output capability of the input voltage source The battery can be charged by a voltage source with limited output current capacity, such as a solar panel. A low-current pre-charge mode is used when the battery voltage is low. The user can set a continuous charging current of 600ma. Maximizing the charging current and preventing the chip from overheating It automatically enters the low-power sleep mode when the power supply voltage is cut off The status indication output can drive led or interface with the microcontroller Automatic recharge Battery temperature monitoring function Lead-free products

The battery charger chip aat3691 is designed to regulate the battery charging voltage and current, and is suitable for 4.2v lithium ion batteries widely used in various portable systems. Because a built-in battery charger chip combines a power device, reverse current blocking and current sensing, the ac adapter input and usb interface designed for this device operate at an input voltage range of 3.0v to 6.75v (typical). In order to maximize safety, aat3691 adds built-in overvoltage protection up to 28v. The ovp block can provide ultra-fast response under 1s. The charging current through an adapter can be programmed to 1.6a, and the charging current through a usb interface using an external resistor can reach 0.5a. When the adapter or USB input power exceeds the typical value of 6.75v, an internal switch group series will be turned on to prevent damage to the battery or charging circuit. The aat3691's total on-resistance (rds (on)) for charging and overvoltage protection is extremely low, at a maximum of only 600 m. The automatic charging selection circuit can identify the best charging source based on the input voltage and other criteria, and adjust the charging path to achieve the shortest charging time. aat3691 also has a no battery input detection function to prevent the input power from overvoltage protection unit from canceling the charge in the absence of a battery state, battery tracking or a defective connector. This new charging chip also provides a series of other protection functions to protect the charging device, control system and battery. The battery charge status is continuously detected to detect fault conditions. Safety features include thermal shutdown protection, power-on reset, and soft start. On the basis of aat3691, Analogicue also introduced a slightly modified version. In addition to providing all the above functions, it also added a built-in low dropout linear regulator (ldo), which will be available in the second quarter of 2009. . During the charging cycle, the ldo can be used as a transceiver or housekeeping microcontroller on a mobile phone or other portable device to power the system, thereby minimizing system current consumption and shortening the charging time.

Thermal management is another big challenge for battery charger designers. Each charger chip experiences a voltage drop due to heat dissipation during the charging process. To avoid battery damage or system shutdown, most chargers integrate some form of control mechanism to manage heat buildup. Older charger chips often use a "not one another" approach to solve overheating or overcurrent problems-they will simply interrupt the charging process when the heat reaches a preset threshold. Newer devices use more sophisticated feedback techniques to continuously monitor die temperature and adjust the charging current dynamically or by calculation at a rate proportional to the ambient temperature change. This built-in intelligence allows current charger chips to gradually reduce the charging current until thermal equilibrium is reached and the die temperature stops rising. This technology allows the charger to continuously charge the battery with the maximum possible current without causing the system to shut down, thereby shortening the battery charging time. The charger chip introduced by max8804, which uses a special thermal adjustment circuit, can limit the temperature of the die during the fast charging stage or when the system is in a high temperature environment. The charger withstands a DC input voltage of 30v and occupies only 6 square millimeters of circuit board area. In addition, chargers like the ti1a bq24060 can provide thermal overload protection, allowing the device to continuously operate in harsh environments with high ambient temperatures, such as summer cars or accidentally connected to other adapters with higher input voltages. Most newer devices today also generally add overvoltage protection mechanisms.