CXLB73307 is a charge management chip designed for multi-string lithium batteries with a buck-boost function for efficient charging over a wide input voltage range. Its built-in fast charge protocol supports 9V or 12V input configuration, greatly simplifying the peripheral circuit design. The chip is packaged in SOP14 and integrates multiple protection mechanisms, including overvoltage and short circuit protection, to ensure that the system can still operate safely under various abnormal conditions.
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[ CXLB73307 ]"
CXLB73307 buck-boost charging management chip: high-performance multi-string lithium battery charging solution
In modern electronic equipment, lithium batteries are used more and more widely, especially in mobile power supplies, power tools and multi-string battery systems, efficient and safe charging management chips are particularly important. As a high-performance buck-boost charging management chip, CXLB73307 can achieve stable and efficient charging no matter when the input voltage is higher than, lower than or equal to the battery voltage, which greatly improves the flexibility and reliability of the system. This article will analyze the functional characteristics, working principle and application design points of the CXLB73307 in depth to help engineers better understand and apply the chip.
Overview and main characteristics of 1. chip
CXLB73307 is a charge management chip designed for multi-string lithium batteries with a buck-boost function for efficient charging over a wide input voltage range. Its built-in fast charge protocol supports 9V or 12V input configuration, greatly simplifying the peripheral circuit design. The chip is packaged in SOP14 and integrates multiple protection mechanisms, including overvoltage and short circuit protection, to ensure that the system can still operate safely under various abnormal conditions.
Its main features include:
· Automatic switching of lift and pressure: Automatically switch the working mode according to the relationship between the input and the battery voltage;
· High precision voltage control: Constant voltage charging accuracy of ± 0.5%;
· Adjustable constant current/constant voltage value: Flexible setting through external resistor;
Built-in fast charge protocolSupport QC2.0, compatible with 9V/12V input;
· Comprehensive protection function: Including short circuit, overvoltage, 0V battery activation, etc;
Clear indicator system: Support charging state, fast charging state and fault indication;
· Wide operating temperature range-20 ℃ ~ 85 ℃, suitable for industrial and consumer products.
2. working principle and charging process
The charging process of the CXLB73307 is divided into three stages:Pre-charge (Trickle Charge),Constant current charging (Constant Current)andConstant voltage charging (Constant Voltage). When the chip detects that the battery voltage is lower than the set threshold (such as VLOWV = 1.285V), it enters the pre-charge mode to restore the battery activity with a small current; then it enters the constant current mode to quickly increase the battery power; when the battery voltage is close to the set value, it turns to the constant voltage mode to gradually reduce the current to ensure the safe full battery.
The chip monitors the battery voltage in real time through the FB pin, and detects the charging current through the CS pin. Its unique 0V battery activation function can restore the fully discharged battery, greatly improving the applicability of the system.
3. Critical Circuit Design Guide
3.1. Charging voltage setting
The constant voltage charging value of the battery can be set by external voltage dividing resistors R12 and R13, and the formula is as follows:
Attention should be paid to the accuracy of the resistor during design. It is recommended to use a resistor with 1% accuracy to ensure the accuracy of the charging voltage.
3.2. Charging current setting
The constant current charging current IIN is determined by the sense resistors RSNS and VIREG:
The VIREG varies with the input voltage, and the appropriate RSNS value needs to be selected according to the actual VCC range during design.
3.3. Fast charging protocol configuration
The CNDP and CNDM pins are used to control the fast charge protocol. The chip supports QC2.0 by default and can be configured as 9V or 12V input through the periphery. Typically, 2 string battery systems are configured for 9V, and 3 strings and above are configured for 12V. When the input voltage is higher than 7V, the QCLED pin outputs a high level, indicating a fast charge state.
4. PCB Layout and Test Recommendations
4.1. Layout Note:
· The input ground is not in common with the battery ground, and the load ground is connected to the battery negative;
· The main current path trace width is not less than 1mm;
· The filter capacitor should be close to the IC pin, and the battery voltage sampling point should be located after the main loop filter.
4.2. TESTING AND CALIBRATION:
The chip supports a test mode, which can be entered by grounding the TEST pin to calibrate the battery voltage detection accuracy. If the charging voltage deviation is found during the test, a compensation resistor can be mounted on the space reserved next to the feedback resistor to adjust the voltage division ratio and ensure that the charging voltage is within the allowable error range.
5. typical application scenarios
CXLB73307 is widely used in:
· Mobile power supply: Support multi-string battery pack to improve output efficiency;
· Electric tools: Adapt to wide voltage input to ensure high-intensity use;
· Industrial Equipment: High temperature resistance, high reliability design, suitable for harsh environments;
· Various types of multi-string lithium battery products: such as sweeper, UAV, outdoor power supply, etc.
6. Typical Application Schematic Diagram
Layout Considerations
1. During application, it should be noted that the input ground and the battery negative are not shared, and the ground of the rear load is connected with the battery negative.
2. As shown in the above figure, the bold trace is the main current loop, and the layout shall be as thick as possible, not less than 1mm.
3. The filter capacitor in the main circuit must be placed on the circuit where the large current passes.
4. The power supply filter capacitor of the main chip should be as close as possible to the Vin and GND of the IC, and the battery voltage feedback and current feedback filter capacitors should also be as close as possible to the IC.
. The sampling point of battery voltage detection must be sampled at the point filtered by the large filter capacitor in the main circuit.
Seven,Package and pin function
EightConclusion
With its efficient buck-boost architecture, flexible configuration and comprehensive protection mechanism, CXLB73307 has become an ideal choice for multi-string lithium battery charging management. Whether in consumer electronics or industrial applications, the chip can provide a stable, safe and efficient charging experience. For more information about CXLB73307 technical information, sample application or purchase information, please visitJTM-IC official website, we will provide you with professional technical support and high-quality service.
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