CXLB73300 is an efficient boost charge management chip designed for dual-cell series Li-ion/polymer batteries. Synchronous rectification architecture and integrated power MOSFET greatly simplify the design of peripheral circuits and significantly reduce the cost of system BOM.
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[ CXLB73300 ]"
Introduction
Today, with the increasing popularity of portable electronic devices, dual series lithium batteries have been widely used in Bluetooth speakers, POS machines, emergency lighting and other products due to their higher voltage and capacity requirements. As a 5V input boost charging management chip designed for dual lithium batteries, CXLB73300 has become an ideal choice for engineers to develop compact charging solutions due to its high integration, excellent thermal performance and simple peripheral circuits. This article will analyze the technical characteristics, application design and configuration methods of the CXLB73300 in depth, and provide a complete reference for product development.
1. CXLB73300 Chip Overview
CXLB73300 is an efficient boost charge management chip designed for dual-cell series Li-ion/polymer batteries. Synchronous rectification architecture and integrated power MOSFET greatly simplify the design of peripheral circuits and significantly reduce the cost of system BOM.
Core parameters:
· Input voltage range: 4V-5.5V (compatible with all types of 5V adapter)
· Output voltage: 8.4V (double lithium battery full charge voltage)
· Maximum charging current: 1A (adjustable by resistance)
· Switching frequency: 900kHz
· Conversion efficiency: up to 90%
· Package options: ESOP-8, DFN3 × 3-8
The chip supports complete short-circuit/current elimination/constant current/constant voltage charging mode, which can intelligently manage the whole charging process to ensure that the battery is safe and fully charged.
2. core features and benefits
2.1. High efficiency and high integration
· Synchronous rectification architecture with up to 90% efficiency
· Integrated power MOSFET without external discrete devices
· 900kHz switching frequency, supporting the use of 1.5 μH small inductors
2.2. Intelligent charging management
· Four-stage charging: short circuit & rarr; current elimination & rarr; constant current & rarr; constant voltage
· Eliminate current charging: restore deep discharge battery
· Constant current charging: maximum 1A fast charging
· Constant voltage charging: accurate 8.4V full charge voltage
2.3. Comprehensive Protection Mechanism
· Input undervoltage/overvoltage protection (4V/6.2V)
· Battery overvoltage, short circuit protection
· NTC temperature protection (supports external thermistor)
· IC over-temperature protection (125 ℃ regulation, 160 ℃ shutdown)
· Charging timeout protection
2.4. Flexible design options.
· Charging current adjustable by external resistor
· Support single lamp/double lamp status indication
· Compact package for space-constrained applications
3. typical application scenarios
CXLB73300 are ideal for the following applications:
· bluetooth speaker: Provide stable high current charging
· POS machine/intercomReliable battery management to ensure device life
· Electronic Cigarette Equipment: Precise charging control to ensure safety
· Micro ProjectorEfficient boost conversion reduces heat generation
· Emergency lighting equipment: Extend battery life with comprehensive protection
· Other Portable Devices: Various electronic products based on dual lithium batteries
Its simple design and excellent performance make it particularly good in cost-sensitive and reliability-critical applications.
4. detailed charging process analysis
The CXLB73300 uses an intelligent four-stage charging algorithm to ensure that the battery is safely and efficiently filled:
4.1. Short circuit charging mode
· When the battery voltage is lower than 2V (typical)
· Safe charging at 10% of the set charging current
· Current limiting via B- FET linear mode
4.2. Current elimination charging mode
· When the battery voltage is between 2V-5.6V
· Pre-charge at 20% of set charge current
· VBD voltage stable at 6V,B-FET operating in linear mode
· If the conversion condition is not reached for more than 30 minutes, an exception will be reported.
4.3. Constant current charging mode
· Enter this mode when the battery voltage exceeds 5.6V
· Fast charging with a set constant current (maximum 1A)
· The B- FET is fully conductive, providing the lowest on-resistance
4.4. Constant voltage charging mode
· Constant voltage mode when the battery voltage is close to 8.4V
· The charging current is gradually reduced to ensure that the battery is fully charged
· Voltage accuracy: 8.30V-8.42V
Charge cut-off: When the charging current drops to 10% of the set value, the chip automatically terminates the charging and indicates the completion of the charging through the STAT pin.
5. Critical Circuit Design Guide
5.1. Charging current setting
Set the charging current through the external resistor of ICHG pin:
Among them:
· ICC: charging current (mA)
· R_{SNS}: Detecting resistance value (kΩ)
For example:
· R_{SNS}=6.4kΩ时，ICC=1000mA
· R_{SNS}=12.8kΩ时，ICC=500mA
5.2. Status indication configuration
The STAT pin supports flexible status indication:
5.2.1. Single lamp scheme:
· Charging: LED is always on (STAT is pulled low)
· Full: LED off (STAT high resistance)
· Anomaly: LED blinking (0.5Hz)
5.2.2. Double lamp scheme:
· Dual charge/full lamp indication via external MOSFET
· The red light is on when charging, and the green light is on when full
5.3. Temperature protection configuration
TS pins support NTC temperature detection:
· Low temperature protection: TS voltage> 75% VIN
· High temperature protection: TS voltage <30% VIN
· Normal range: TS voltage between 30%-75% VIN
· Disable protection: TS pin is directly grounded
It is recommended to connect a 100nF capacitor in parallel at the TS pin to improve the anti-interference ability.
Recommendations for selection of 6. components
Based on typical applications, key components include:
· power inductance: 1.5 μH, saturation current> 4.5A,DCR as small as possible
· Input capacitance: 4.7 μF-10μF/25V ceramic capacitor (near VIN pin)
· Output capacitance10 μF/25V Ceramic Capacitor (BAT Pin)
· BD Capacitor10 μF/25V Ceramic Capacitor (Boost Output)
· bootstrap capacitance: 22nF/16V (between BS-LX)
· RC snubber: 2Ω 1nF(LX to ground, ringing suppressed)
Important Recommendations for 7. PCB Layout
Proper PCB layout is critical to system performance and stability:
7.1. Power path optimization
· Short and thick routing of LX node reduces switching noise and loss
· Power ground (PGND) and analog ground (AGND) are single-point connected under the chip
· High current path using large area copper clad
7.2. Capacitor Layout
· Input and output capacitors as close as possible to the corresponding pin
· VIN capacitor ground directly connected to PGND
· The BD capacitor has the highest priority and must be closest to the pin
7.3. Thermal design
· The EPAD at the bottom of the chip is connected to a large area of copper and punched for heat dissipation.
· Keep proper distance between power inductor and chip
· Ensure good air circulation for heat dissipation
7.4. Signal isolation
· ICHG, TS and other signal lines away from the LX switch node
· STAT indication line to avoid parallel routing with power line
Detailed explanation of 8. protection function
8.1. Input voltage protection
· Under-voltage protection: 4V (hysteresis 400mV)
· Overvoltage protection: 6.2V (hysteresis 700mV)
· Adaptive current limit: automatic downflow when VIN<4.5V
8.2. Battery protection
· Overvoltage Protection: 105%-115% VCV
· Short circuit protection: enter special charging mode when VBAT<2V
· Temperature protection: via external NTC
8.3. Chip self-protection
· Thermal regulation: linear reduction of charging current at 125°C
· Thermal shutdown: Completely stop charging at 160°C (30°C hysteresis)
9. Typical Application Bill of Material
Based on typical application schematics, the main components include:
· IC：CXLB73300E（ESOP-8）或CXLB73300D（DFN3×3-8）
· Power inductance: 1.5 μH, saturation current> 4.5A
· Capacitance: 10 μF × 2,4.7 μF × 1,22nF × 1,100nF × 1,1nF × 1
· Resistance: 6.4 kΩ(ICHG setting),2 Ω(Snubber)
· LED: According to the selected indication scheme
· NTC: Select according to temperature requirements (optional)
10. technical support and supply information
JTM-IC（jtm-ic.com) As the official authorized supplier of CXLB73300, provide comprehensive technical support:
· Sample application and bulk supply service
· Reference design, PCB review and optimization suggestions
· Professional and technical Q & A and fault analysis
· Complete design documentation, data sheets and application notes
XI,Package and pin function
XII. Conclusion
CXLB73300 with its high integration, excellent performance and comprehensive protection function, become the ideal choice for dual lithium battery charging applications. Whether in the fields of consumer electronics, industrial equipment or emergency lighting, its stable and reliable performance can provide strong support for end products. Welcome to visitJTM-IC official websiteGet detailed technical information, apply for samples or consult professional design support.
