CXLB73299 is an efficient synchronous boost charge management chip designed for 2 or 3 strings of Li-ion/polymer batteries. In a 4 × 4mm QFN24 package, the power MOSFET, equalization circuit and fast charge protocol controller are integrated, providing an unprecedented level of integration.
-
[ CXLB73299 ]"
Introduction
As the requirements for charging speed and battery safety of portable devices continue to increase, efficient charging solutions that support multiple series-connected lithium batteries become increasingly important. As a high-performance boost charging management chip integrating 15W fast charging, battery equalization and intelligent temperature control functions, CXLB73299 has become an ideal choice for large-capacity battery charging applications with its excellent integration and flexible configuration capabilities. This article will fully analyze the technical characteristics of the CXLB73299, application design and configuration methods, and provide engineers with a complete design reference.
1. CXLB73299 Chip Overview
CXLB73299 is an efficient synchronous boost charge management chip designed for 2 or 3 strings of Li-ion/polymer batteries. In a 4 × 4mm QFN24 package, the power MOSFET, equalization circuit and fast charge protocol controller are integrated, providing an unprecedented level of integration.
Core parameters:
· Input voltage range: 4.5V-9.5V (support 5V/9V fast charge)
· Maximum output power: 15W
· Constant current charging current: up to 1.5A
· Switching frequency: 500KHz
· Conversion efficiency: 94% for 2 strings and 91.5 for 3 strings
The chip supports flexible configuration of charging voltage, current, protection threshold and other parameters through external resistors, providing accurate charging management for different application scenarios.
2. core features and benefits
2.1. High efficiency and high power
· Synchronous Boost Architecture with 94% Peak Efficiency
· 15W maximum input power, support fast charging
· 500KHz switching frequency, support 2.2μH small inductor
2.2. Application for Intelligent Fast Charging
· According to the battery voltage automatically apply for fast charge input
· 2 string application: the highest application 7V input
· 3 string application: maximum application 9V input
· Support DP/DM fast charging protocol communication
2.3. Battery equalization function
· Integrated 2-string battery equalization circuit
· Real-time monitoring of each battery voltage
· Adjustable equalization current (maximum 40mA)
· Equilibrium opening voltage: 4.1V (standard)
2.4. Comprehensive Protection Mechanism
· NTC temperature protection: support battery temperature monitoring
· Input undervoltage/overvoltage protection (threshold adjustable)
· Output overcurrent, overvoltage, short circuit protection
· IC over-temperature protection (135 ℃ shutdown)
· Programmable Charge Timeout Protection
2.5. Flexible parameter configuration.
· Adjustable charging voltage and current
· Input protection threshold adjustable
· Charging timeout time can be set
· 2 String/3 String Mode Pin Select
3. typical application scenarios
CXLB73299 are ideal for the following applications:
· High-end mobile power supply: 15W fast charge, support multiple batteries
· Electric tools: High current charging, integrated equalization protection
· Medical Equipment: Precise charging management to ensure safe and reliable
· Industrial EquipmentData collector, test instrument
· High-end consumer electronicsLarge-capacity Bluetooth speaker, portable display
Its highly integrated features and flexible configuration capabilities make it particularly effective in applications requiring high efficiency and high security.
4. detailed charging process analysis
CXLB73299 uses an intelligent multi-stage charging algorithm to ensure safe and efficient battery charging:
4.1. 2 series battery application (CON_SEL suspended):
4.1.1 Short-circuit charging: When the battery voltage is <3.7V, charge with 50mA current
4.1.2 Current elimination charging: When 3.7V
4.1.3 constant current charging: When the battery voltage is> 6V, fast charging at the set current
4.1.4 constant voltage charging: Turn to constant voltage mode when approaching the set voltage
4.2. Application of 3 series batteries (CON_SEL connected to 1K resistor to ground):
4.2.1 Short-circuit charging: When the battery voltage is <3.7V, charge with 50mA current
4.2.2 Current elimination charging: When 3.7V
4.2.3 constant current charging: When the battery voltage is> 9V, fast charging at the set current
4.2.4 constant voltage charging: Turn to constant voltage mode when approaching the set voltage
Automatic recharge function: After the battery is fully charged, if the voltage drops (2 strings to 8V,3 strings to 12V), the chip will automatically restart the charging cycle.
5. intelligent fast charging application mechanism
The CXLB73299 can intelligently apply for fast charging input according to the battery voltage, significantly improving charging efficiency:
5.1. 2 String Configuration:
· VBAT<6.2V:5V input charging
· 6.2V ≤ VBAT<6.8V: apply for 5.4V fast charging
· 6.8V ≤ VBAT<7.8V: apply for 6V fast charging
· VBAT ≥ 7.8V: apply for 7V fast charging
5.2. 3 string configuration:
· VBAT<9V:5V input charging
· 9V ≤ VBAT<10.5V: apply for 7V fast charging
· VBAT ≥ 10.5V: apply for 9V fast charging
If the fast charging application fails, the chip automatically reverts to 5V input charging to ensure compatibility.
6. Critical Circuit Design Guide
6.1. Working mode selection
Configuration via CON_SEL pins:
· Suspended: 2-string charging mode
· 1K resistor to ground: 3 series charging mode
6.2. Charging voltage setting
External resistor setting via VSET pin:
|
R_VSET Resistance |
2 string charging voltage |
3 string charging voltage |
|---|---|---|
|
1K |
8.1V |
12.3V |
|
68K |
8.2V |
12.4V |
|
120K |
8.3V |
12.5V |
|
Suspended |
8.4V |
12.6V |
6.3. Charging current setting
Set constant current charging current through ISET pin external resistor, accuracy ± 10%
6.4. Protection Threshold Configuration
· Input undervoltage: Set via RUV (4.25V-4.65V)
· Input overvoltage: Set via ROV (can be disabled)
· Charging timeout: Set via ROT (4H-24H, can be disabled)
6.5. NTC temperature protection
· NTC Pin Output 20μA Current Detection
· Normal range: 0.56V-1.32V(100% current)
· High temperature: 0.43V-0.56V(50% current)
· Abnormal temperature: stop charging
· Disable NTC: 51K resistor to ground
When the CXLB73299 detects that the NTC pin voltage is between 0.56V and 1.32V, it means that the battery temperature is normal and the battery is charged normally.
When the CXLB73299 detects that the NTC pin voltage is between 0.43V and 0.56V, it indicates that the battery temperature is high and the charging current is reduced by half.
When the CXLB73299 detects that the NTC pin voltage drops to less than 0.43V, the battery temperature is too high and the charging is stopped.
When the CXLB73299 detects that the NTC pin voltage rises to more than 1.32V, it indicates that the battery temperature is too low and stops charging.
Example: RNTC = 100K thermistor (B = 4100) , R2 = 82K, corresponding temperature and NTC pin voltage:
6.6. Battery equalization configuration
· Set equalization current via RGB resistors (ICB = VCB/RCB)
· RGB should be greater than 100 Ω, equalization current <40mA
· VBATM and VBAT_GND are floating when equalization is not used
CXLB73299 integrates 2 series of charging equalization functions; When the equalization function is not used, the relevant pins (pins 23 and 24) can be suspended. During the charging process,
The CXLB73299 will detect the battery voltage of 2 batteries in real time. When it detects that any battery voltage reaches the balanced opening voltage VCBON, it will turn on
CXLB73299 the internal corresponding equalization MOS to reduce the charging current of the battery:
The voltage of 1 and 2 batteries is higher than the balanced opening voltage VCBON;
2. Exit the normal charging state (such as NTC protection, input overvoltage, battery full, etc.);
The equalization current can be set by adjusting the RCB. The equalization current will be consumed on the internal equalization MOS and RCB in the form of heat, so the equalization
The current setting should be less than 40mA (RCB should be greater than 100 ohms),ICB = VCB/RCB;
Equilibrium opening voltage VCBON of standard product = 4.1V;
6.7. Charging process
CXLB73299 with full CC/CV charging mode
When configured for 2-string charging:
When the battery voltage is less than 3.7V, the battery is charged at a current of 50mA.
When the battery voltage is greater than 3.7V and less than 6V, the battery is charged with a current of 100mA.
When the battery voltage is greater than 6V, it is charged with the set constant current ICC;
When the battery voltage approaches 8.4V, the constant voltage charging mode is entered.
After the battery is fully charged and stopped, and the input continues to exist, if the battery voltage is less than 8V, it will start charging again;
When configured for 3-string charging:
When the battery voltage is less than 3.7V, the battery is charged at a current of 50mA.
When the battery voltage is greater than 3.7V and less than 9V, the battery is charged with a current of 100mA.
When the battery voltage is greater than 9V, it is charged with the set constant current ICC;
When the battery voltage is close to 12.6V, the constant voltage charging mode is entered.
After the battery is fully charged and stopped, and the input continues to exist, if the battery voltage is less than 12V, it will start charging again;
After entering the constant voltage mode, if the charging current is less than 200mA, stop charging after 30s, and check whether the battery voltage is higher than the stop charging voltage; If high
When the charging voltage is stopped, the charging will be stopped. If it is lower than the stop charging voltage, the charging will be continued, and the detection will be continued after another 30s.
6.8. Enter the application for quick charging
The CXLB73299 can apply for fast charging voltage to the input terminal through DP/DM according to the current battery voltage;
When configured for 2-string charging:
When the battery voltage VBAT<6.2V, do not apply for fast charging, just 5V input charging;
When the battery voltage is 6.2V<= VBAT<6.8V, it will try to apply for 5.4V input fast charging;
When the battery voltage is 6.8V<= VBAT<7.8V, it will try to apply for 6V input fast charging;
When the battery voltage VBAT>= 7.8V, it will try to apply for 7V input fast charging;
When configured for 3-string charging:
When the battery voltage VBAT<9V, do not apply for fast charging, just 5V input charging;
When the battery voltage is 9V<= VBAT<10.5V, it will try to apply for 7V input fast charging;
When the battery voltage VBAT>= 10.5V, it will try to apply for 9V input fast charging;
If you cannot successfully apply for fast charging input, you will always charge with 5V input;
6.9. Charging protection
It has perfect protection function, integrated output overcurrent, input undervoltage, overvoltage, overtemperature and other protection functions to ensure stable and reliable operation of the system.
Make.
The CXLB73299 has an input VIN input regulator loop, which will automatically adjust the drop when it detects that the input voltage is close to the input undervoltage threshold set by the RUV.
Low charging current ensures that the input voltage is stable near the input undervoltage threshold, ensuring that the adapter will not be pulled.
CXLB73299 integrated input overvoltage protection stops charging when the input voltage is detected to be greater than the overvoltage threshold set by the ROV.
CXLB73299 integrated NTC function, with NTC resistor, can detect the battery temperature, when the battery temperature is detected to be too high or too low, you can stop
Charging.
CXLB73299 integrated over-temperature protection function, when the internal temperature of the chip is detected to exceed 135 degrees, the charging will be forced to stop.
CXLB73299 integrated charging timeout protection, when the charging time exceeds the maximum charging time set by ROT, the charging will be forced to stop.
9.10. Input undervoltage threshold setting
CXLB73299 support VIN_UVSET pin external resistor RUV to set the input undervoltage threshold;
RUV Set Input Undervoltage Threshold
When the CXLB73299VIN input loop detects that the input voltage is close to the set input undervoltage threshold, it will automatically adjust and reduce the charging current to ensure that
The input voltage stabilizes near the input undervoltage threshold to ensure that the adapter is not pulled.
9.11 Input Overvoltage Threshold Setting
CXLB73299 support VIN_OVSET pin external resistor ROV to set the input overvoltage threshold;
ROV Set Input Overvoltage Threshold
9.12 charging timeout setting
CXLB73299 support TIME_SET pin external resistor ROT to set the charging timeout time;
ROT Set charging timeout
Important Recommendations for 7. PCB Layout
Proper PCB layout is critical to system performance and stability:
7.1. Power path optimization
· VSYS capacitor (2 × 22 μF) close to chip pin
· LX node trace short and thick, reduce switching noise
· High current path using large area copper clad
7.2. Thermal design
· The bottom ePad is connected to a large area of copper sheet and punched for heat dissipation.
· Keep proper distance between power inductor and chip
· Use multiple vias to connect each layer of ground plane
7.3. signal isolation
· Configure signal lines (VSET, ISET, etc.) away from the LX switch node
· Sensitive signals using separate ground loops
· NTC resistance away from heating elements
7.4. Fast charge signal line
· DP/DM trace length matching to avoid signal distortion
· Keep away from high-frequency switch nodes to reduce interference
8. Typical Application Bill of Material
Based on typical application schematics, the main components include:
· IC: cxlb73299 × 1
· Power inductance: 2.2 μH, saturation current> 5A × 1
· Capacitance: 10 μF × 4,22 μF × 2,0.1 μF × 1
· Configuration resistance: RVSET, RISET, RUV, ROV, ROT, RCON each × 1
· LED and current limiting resistor: 0603 package × 1
· NTC resistance: select × 1 according to temperature requirements
9. technical support and supply information
JTM-IC（jtm-ic.com) As the official authorized supplier of CXLB73299, provide comprehensive technical support:
· Sample application and bulk supply service
· Reference design, PCB review and optimization suggestions
· Professional and technical Q & A and customized solution development
· Complete design documentation, data sheets and application notes
Ten, typical application schematic diagram and BOM
Ten,Package and pin function
Eleven, working conditions and parameters
11.1 limit parameter
11.2 working conditions
Twelve,Conclusion
With its excellent integration, intelligent fast charging application and battery equalization function, the CXLB73299 has set a new standard for 2 string/3 string lithium battery charging applications. Whether in high-end consumer electronics, power tools or industrial equipment, its excellent performance and comprehensive protection functions can provide strong support for end products. Welcome to visitJTM-IC official websiteGet detailed technical information, apply for samples or consult professional design support.
