CXLB73302 is an integrated management circuit designed for 5V input and multi-string lithium battery boost charging. The chip supports an external NMOS power tube, and users can flexibly select according to the actual charging current demand, taking into account the design freedom and system cost. Its switching frequency is 250kHz, which supports complete current elimination, constant current and constant voltage charging modes. The typical charging efficiency is 90%, which is excellent in similar products.
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[ CXLB73302 ]"
In all kinds of portable audio, power tools, POS machines and smart home equipment is becoming more and more popular today, multi-string lithium batteries (such as 2~3 series) are more and more widely used. However, how to use the common 5V USB power supply to charge multiple lithium batteries efficiently and safely has become a design challenge faced by many engineers. As a boost charge management chip designed for multi-string lithium batteries or lithium iron phosphate batteries, CXLB73302 is an ideal solution with its 90% conversion efficiency, flexible external MOS design and complete charge management functions. This article will analyze the technical characteristics, working principle, typical applications and design suggestions of the CXLB73302 in depth to help developers build high-performance and high-reliability charging systems.
1. CXLB73302 overview: Flexible and efficient multi-string battery charging solution
CXLB73302 is an integrated management circuit designed for 5V input and multi-string lithium battery boost charging. The chip supports an external NMOS power tube, and users can flexibly select according to the actual charging current demand, taking into account the design freedom and system cost. Its switching frequency is 250kHz, which supports complete current elimination, constant current and constant voltage charging modes. The typical charging efficiency is 90%, which is excellent in similar products.
The chip uses SOP8 and DFN 400.00g packages, which are suitable for scenarios with different space and heat dissipation requirements. Its input voltage range is 4.5V ~ 6V, which perfectly matches the standard USB power output. It is widely used in singing machines, loudspeakers, Bluetooth audio, POS machines, power tools and other products.
Detailed explanation of the core functional characteristics of the 2.
2.1. Complete three-stage charging management
CXLB73302 support the classic elimination of current, constant current, constant voltage charging process:
· Current elimination charging: When the battery voltage is lower than the set threshold, perform small current pre-charging with 15% of the constant current value to effectively activate the deep discharge battery;
· Constant current charging: Set the charging current through the external current detection resistor, and replenish the energy for the battery stably and efficiently;
· Constant voltage charging: When the battery voltage is close to the set value, it will automatically switch to constant voltage mode, and the current will gradually drop until it is fully charged.
2.2. High-precision voltage and current settings
· Constant voltage setting: Feedback to FB pin through external resistor voltage divider network, setting formula: VBAT = 1.8 × (R3 R4) / R4;
· Constant current setting: Set by external current detection resistor R10 on CS pin, and the formula is ICC = 0.1V / R10;
· Automatic recharging: Automatically restart charging after the battery voltage drops, and the charging threshold is: VBAT = 1.73 × (R3 R4)/R4.
2.3. Efficient external MOS architecture
The chip adopts an external NMOS design, and the user can select the appropriate power tube according to the output power requirement, which not only improves the flexibility of the system, but also optimizes the overall heat dissipation and efficiency performance. The DRV pin provides strong driving capability (high level 27mA, low level 80mA) to ensure fast switching of MOS transistors and reduce losses.
2.4. Intelligent protection and status indication
· Soft start function: Effectively suppress the impulse current at startup;
· dual state indication: The CHRG pin outputs a high level during charging, and the DONE pin outputs a high level after it is fully charged. With LED, the system status can be visually displayed;
· enable control: Start charging when the EN pin is grounded, and close when it is suspended, which is convenient for system control and energy saving management.
2.5. Good temperature adaptability
The operating temperature range of the chip is -40 ℃ to 85 ℃, which meets the environmental requirements of industrial and consumer electronics products. The packaging materials meet the RoHS environmental protection standards of lead-free and halogen-free.
3. typical application scenarios
3.1. Portable Audio Equipment
Such as Bluetooth speakers, loudspeakers, singing machines, etc., often using 2 to 3 strings of lithium battery power supply. CXLB73302 can use 5V input to achieve efficient boost charging, improve user experience and device life.
3.2. Power Tools and Gardening Equipment
Hand-held electric drills, angle grinders, trimmers and other tools require high charging speed and reliability. CXLB73302 with the appropriate external MOS, can support large current charging, and has good temperature adaptability.
3.3. Commercial payments and terminal equipment.
POS machines, code scanning guns and other equipment need to be charged and discharged frequently, and the automatic recharge and high efficiency characteristics of the CXLB73302 can ensure that the equipment is in a usable state at any time.
3.4. Smart Home and Internet of Things Devices
Such as household robots, security cameras, intelligent lighting systems, etc., can use the chip to build a compact, efficient multi-string battery charging circuit.
4. design guidelines and practical recommendations
4.1. Selection of key peripheral components
· power inductance: It is recommended to use power inductors with saturation current greater than 5A and low DCR, such as 6.8 μH/5A specifications, to ensure stable operation at 250kHz switching frequency;
· Current detection resistance: A low-temperature drift resistor with an accuracy of 1%, such as 0.05 Ω/1206, should be selected to ensure the accuracy of constant current charging;
· voltage dividing resistance: R3, R4 recommended the selection of 1% precision resistor, to ensure that the constant voltage charging voltage accurate;
· Output capacitance: It is recommended to configure a low ESR ceramic capacitor with a capacity of 22μF and above at the battery end to smooth the output ripple.
4.2. PCB Layout and Grounding Strategy
· Power Path: VIN-inductor-MOS-battery loop should be as short and wide as possible to reduce parasitic inductance and resistance;
· Signal ground separation: The current detection resistor of CS pin should be connected to the battery ground nearby to avoid power noise interference;
· Heat dissipation design: Sufficient copper area should be reserved for external MOS, and the thermal pad at the bottom of DFN package chip should be well grounded and dissipated.
4.3. State indication circuit design
The output high level of CHRG and DONE pins is VIN voltage. When driving LED, a current limiting resistor (such as 1kΩ) needs to be connected in series, and a diode can also be used to realize two-color indication to enhance human-computer interaction experience.
Why did 5. choose CXLB73302?
In the current multi-string lithium battery charging chip market, CXLB73302 to "external MOS flexible selection, high charging efficiency, system cost is excellent" as the core competitiveness. Its complete three-stage charge management and high-precision control capabilities can effectively extend battery life and improve charging safety. Whether you are a start-up team, a mature enterprise or a solution developer, CXLB73302 can provide you with reliable, flexible and cost-effective power solutions.
6. Typical Application Schematic Diagram and BOM
Seven, package and pin function
8. epilogue
As the market for portable electronic devices and power tools continues to expand, efficient, flexible and safe battery charging solutions have become a key element of product success. With its excellent system adaptability, high conversion efficiency and complete management functions, CXLB73302 is becoming the preferred chip for multi-string lithium battery applications.
If you are looking for a multi-string battery boost charge management IC with stable performance, flexible design and outstanding cost performance, CXLB73302 is worth your attention. Welcome to visitJTM-IC official websiteAccess data sheets, DEMO board materials and comprehensive technical support to JTM-IC together to create a smarter and more reliable power future.
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