CXLB73296是一款支持四节串联锂离子/聚合物电池的同步升压充电芯片，输入电压范围宽达3.0V–12.3V，兼容5V适配器与PD 9V输入（需诱骗芯片），最大充电电流可达2A。芯片内部集成全部功率MOSFET，无需外接二极管，极大简化了外围电路设计。
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[ CXLB73296 ]"
Introduction
With the increasing demand for battery capacity and voltage in portable devices, four cell series connected lithium batteries are widely used in high-power mobile power supplies, smart door locks, portable game consoles, and other products due to their higher energy density and output voltage. CXLB73296, as an efficient synchronous boost charging management chip designed specifically for four lithium batteries, has become an ideal choice for engineers due to its high integration, flexible configuration, and multiple protection functions. This article will comprehensively analyze the core features, application design, and selection points of CXLB73296 to assist in efficient product development.
I. Overview of CXLB73296
CXLB73296 is a synchronous boost charging chip that supports four series connected lithium-ion/polymer batteries. It has a wide input voltage range of 3.0V-12.3V and is compatible with 5V adapters and PD 9V inputs (requiring a decoy chip). The maximum charging current can reach 2A. The chip integrates all power MOSFETs without the need for external diodes, greatly simplifying peripheral circuit design.
CXLB73296 has four intelligent charging modes:
· Short circuit charging: Supports safe wake-up of 0V batteries;
· Current dissipation charging: Restore deep discharge batteries;
· Constant current charging: Achieve fast charging;;
· Constant voltage charging: Ensure that the battery is fully charged and not overcharged.
When the charging current drops to 1/10 of the set value, the chip automatically terminates charging and continuously monitors the battery voltage, supporting automatic recharging. When there is no input power, the battery leakage current is as low as 35 μ A, effectively extending standby time.
II. Core Features
2.1 高效能与高可靠性
· 峰值效率96%，重载效率超过90%；
· 输入/电池端耐压高达28V，适用多种适配器；
· 内置1MHz开关频率，优化系统尺寸与效率。
2.2. 灵活的参数配置
· 充电电流通过外接电阻编程；
· 充满电压支持16.8V、17.2V、17.4V、17.6V四档可调；
· 支持NTC温度检测，确保充电安全。
2.3.Comprehensive protection mechanism
· Input overvoltage/undervoltage protection;
· Battery overvoltage, short circuit, and abnormal temperature protection;
· Programmable charging timeout protection;
· 160 Shutdown due to overheating at ℃.
2.4. Intelligent Control and Indication
· Support single/dual LED charging status indication;
· SYSRT Pin can control the load switch of the rear stage;
· EN The pins support external shutdown, which facilitates system management.
2.5. Encapsulation Options
· QFN3 3-16 (ultra small size, suitable for compact design)
· ESSOP10（ Excellent heat dissipation, θJA=43.4℃/W）
III. Typical Application Scenarios
CXLB73296 is widely used in:
· Large capacity portable power bank: Supports 2A fast charging, high efficiency, low heat generation;
· Smart door lock: Low temperature charging protection, extending battery life;
· Portable gaming consoles (such as PSP, NDS): stable power supply to enhance user experience;
· Industrial handheld devices: Wide input voltage range, suitable for various power environments.
IV. Key Circuit Design Guidelines
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●NTC 电阻一般位于电池内部，为方便展示，虚线框内为电池包。NTC 典型应用中需使用 B 值为 4250K 的 100K
阻值的 NTC 电阻与 R2(150K)电阻器并联再与 R1(57.6K)电阻器串联接于 VDD 引脚，这种搭配可保证电池在 0℃
~60℃区间正常充电。如使用其他搭配，请参照第 13 页 NTC 功能解释中的给出的各温度阈值区间的 NTC 电压
进行设计或可咨询我司 FAE。
●对底部 ePad GND 引脚，应使用较大覆铜区域连接到 PCB 地平面，这有助于最大限度的减小 PCB 传导损耗和
热应力，防止因芯片温度过高导致的充电电流下降。
●LED 指示灯使用时需接限流电阻到 VDD，推荐 3K。如需使用双灯方案，必须按照图中 LED 灯颜色配置，请购
买对应颜色 LED 灯进行实验，充电时红灯亮，蓝灯灭；充满时蓝灯亮，红灯灭；异常时红灯蓝灯交替闪烁。
4.1. Charging current setting
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●NTC 电阻一般位于电池内部，为方便展示，虚线框内为电池包。NTC 典型应用中需使用 B 值为 4250K 的 100K
阻值的 NTC 电阻与 R2(150K)电阻器并联再与 R1(57.6K)电阻器串联接于 VDD 引脚，这种搭配可保证电池在 0℃
~60℃区间正常充电。如使用其他搭配，请参照第 13 页 NTC 功能解释中的给出的各温度阈值区间的 NTC 电压
进行设计或可咨询我司 FAE。
●对底部 ePad GND 引脚，应使用较大覆铜区域连接到 PCB 地平面，这有助于最大限度的减小 PCB 传导损耗和
热应力，防止因芯片温度过高导致的充电电流下降。
●LED 指示灯使用时需接限流电阻到 VDD，推荐 3K。如需使用双灯方案，必须按照图中 LED 灯颜色配置，请购
买对应颜色 LED 灯进行实验，充电时红灯亮，蓝灯灭；充满时蓝灯亮，红灯灭；异常时红灯蓝灯交替闪烁。
Set the charging current through the ICHG pin external resistor RICHG, using the following formula:
Where VICHGis 1V in constant current mode. For example, when RICHG=1K, the charging current is 1A.
4.2. Output voltage settings
Set the full voltage through an external RCV resistor connected to the CV pin:
· RCY ≤ 2.5K：16.8V
· RCY = 7.5K：17.2V
· RCY = 25K：17.4V
· RCY ≥ 75K：17.6V
4.3. NTC温度检测
使用10K NTC（B=3380K）与R1=16K、R2=3K组成分压网络，可实现0℃~60℃正常充电。若禁用NTC，可用两个10K电阻分压使NTC引脚电压为50% VDD。
4.4. 自适应输入限流
通过ILIM引脚设置输入电压阈值，当输入电压跌落时自动调整充电电流，避免适配器过载，提升系统稳定性。
五、PCB布局建议
· 功率回路最短化：LX、BD、BAT等大电流路径应宽铜走线；
· 电容就近放置：CBD（10μF）必须最靠近BD引脚，CBAT（20μF）靠近BAT；
· 散热设计：底部ePad应连接大面积覆铜并打孔散热；
· 信号隔离：ICHG、TIM、NTC等信号线远离LX开关节点，使用SGND。
VI. Purchasing and Technical Support
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· Sample application and bulk supply;
· Reference design and PCB review;
· FAE Online Q&A and customized services.
7. Packaging and Pin Functions
八，结语
CXLB73296以其高集成度、高效率与多重保护功能，成为四节锂电池充电方案的优选芯片。无论是在大容量移动电源、智能门锁还是工业设备中，其稳定可靠的性能都能显著提升产品竞争力。欢迎访问JTM-IC官网了解更多详情，获取数据手册、设计资源与样品申请支持。
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