CXLB73269 is a high-frequency PWM step-down charging management chip that supports solar panel power supply. The input voltage range is 6.5V to 30V, which can output up to 6A of charging current and independently manage the complete charging process of two lithium batteries. Its internal integration of maximum power point tracking (MPPT) circuit can automatically optimize the energy collection of solar panels without user intervention, greatly improving the energy utilization efficiency of the solar system. The device is packaged in TSSOP-16 and the peripheral components are simplified, which is very suitable for portable devices with limited space.
-
[ CXLB73269 ]"
CXLB73269: efficient charging management solution for solar power supply double lithium batteries with integrated MPPT
With the rapid development of green energy and portable equipment, the combination of solar power supply system and efficient battery management has become the first choice for many applications. CXLB73269 as a PWM step-down dual lithium battery charging management integrated circuit specially designed for solar power supply, it has become an industrial handheld device with its high integration, powerful charging capability and intelligent power tracking function, ideal Power Solutions for standby power supply, portable medical instruments and other fields. This article will comprehensively analyze the technical highlights, working modes and design points of CXLB73269, and help engineers to build an efficient, safe and reliable battery charging system.
I. Product Overview
CXLB73269 is a high-frequency PWM step-down charging management chip that supports solar panel power supply. The input voltage range is 6.5V to 30V, which can output up to 6A of charging current and independently manage the complete charging process of two lithium batteries. Its internal integration of maximum power point tracking (MPPT) circuit can automatically optimize the energy collection of solar panels without user intervention, greatly improving the energy utilization efficiency of the solar system. The device is packaged in TSSOP-16 and the peripheral components are simplified, which is very suitable for portable devices with limited space.
Second, core features
• Wide input voltage range: 6.5V-30V, suitable for a variety of power input, including solar panels, adapters, etc.
• Large current charging capability: the constant current charging current is up to 6A, which supports fast charging applications.
• MPPT maximum power point tracking: automatically track the best working point of solar panels to improve energy utilization.
• Three-stage charging management: includes current elimination, constant current, and constant voltage charging modes to fully protect battery health.
• High-precision constant voltage output: 8.4V ± 1% charging cut-off voltage, high precision and good stability.
• JEITA Standard Temperature Monitoring: monitor the battery temperature in real time through external NTC resistance and dynamically adjust the charging parameters.
• Comprehensive protection mechanism: it has the functions of input undervoltage latching, battery overvoltage protection, battery current backfilling prevention, overheating protection, etc.
• Low Power Sleep mode: When the input power is down or the voltage is lower than the battery voltage, the sleep mode is automatically entered, and the static current is only 3.6 μA.
• Dual status indicator output: CHRG and DONE pins indicate the charging status and charging completion respectively.
• Environmentally friendly packaging: TSSOP-16 lead-free package, which meets Rohs and halogen-free requirements.
Third, typical application scenarios
CXLB73269 is widely used in the following fields:
•Solar powered field monitoring equipment, outdoor sound box
•Handheld industrial instruments, portable medical equipment
•Power tools, backup battery system
•Two lithium batteries charging set, mobile power supply
•Various embedded battery management modules
IV. Electrical characteristics and performance advantages
Under the typical conditions of input 15V and ambient temperature 25℃, CXLB73269 shows the following superior performance:
•Enter UVLO threshold: 5V (typical)
•Constant voltage charging voltage: 8.4V ± 1%
•Constant current charging reference: 100mV (voltage between CSP-BAT)
•Current elimination charging threshold:66.6% × VREG
•End-of-charge threshold:15% × ICC
•MPPT pin voltage: 1.205V
•Switching frequency: 550kHz, small size inductor can be used
•Sleep mode wake-up threshold:0.25V(VIN-VBAT)
Its intelligent temperature monitoring system strictly follows JEITA standard and automatically adjusts the charging current and voltage according to the battery temperature to ensure safe and efficient charging of the battery in all-weather environment.
V. Design guide and selection of key components
5.1. Charging current setting
Constant current charging current is determined by the detection resistor RCS, and the calculation formula is as follows:
We recommend that you select metal film resistor with high precision and good temperature characteristics.
5.2. MPPT resistance voltage dividing network
The maximum power point voltage of the solar panel is set by R1 and R2:
Reasonable value selection can realize the best power tracking of solar panels of different specifications.
5.3 battery temperature monitoring
The TEMP pin needs to be connected with a 10 kOhm NTC resistor to GND to achieve:
•0 ℃-10 ℃ (cold): the charging current is reduced to 25% ICC
•10 ℃-45 ℃ (normal): full charge
•45 ℃-55 ℃ (partial heat): charging current drops to 50% ICC, voltage drops to 97.91% VREG
•Beyond 0 ℃-55 ℃: suspend charging
If the temperature control function is not enabled, 10 kOhm Fixed resistor should be connected between TEMP and GND.
5.4. Power inductor selection
To limit ripple current to less than 30% ICH, the inductance value should meet the following requirements:
Where f = 550kHz. We recommend that you select power inductor with high saturation current and low DCR.
5.5. Filter capacitor configuration
•Input capacitance: At least 1μf (close to VIN) is configured in combination with a large capacity electrolytic ceramic capacitor to absorb ripple.
•Output capacitor: Place a 1Off ceramic capacitor near the BAT pin, and connect a low ESR Capacitor to suppress the output voltage ripple.
5.6. Selection of MOSFETs
•N-MOS(M1, M2): Vth<5V,Rds(on) meets VICH× Rds(on) <55mV,BVdss must be higher than VIN.
•P-MOS(M3, anti-backfilling): Rds(on) is small, BVdss > VIN,Vgs_max ≥ 12V.
VI. Layout and heat dissipation suggestions
Good PCB design is crucial to performance:
•Arrange the high-current path components such as input and output capacitors, inductors, and current detection resistances as close as possible to the chip.
•Power ground (PGND) and analog ground (GND) should be routed separately and connected at a single point.
•The CSPS and BAT pins should be directly and symmetrically connected to the detection resistor to ensure the current sampling accuracy.
•Expand the copper cover area at the bottom of the chip to enhance heat dissipation, especially in high input voltage or high current applications.
VII. Packaging and supply information
CXLB73269 is packaged in TSSOP-16, with compact size and good heat dissipation. It supports reel packaging (4000 pieces per plate), which is convenient for large-scale production.
VIII. Conclusion
CXLB73269 has become the preferred solution for charging management of two lithium batteries due to its high integration, solar MPPT function, comprehensive battery protection mechanism and powerful 6A charging capability. Whether in outdoor solar energy equipment, industrial handheld terminal or high-end consumer electronics, its excellent performance and high reliability can meet the stringent requirements of modern electronic systems for power management. For detailed data manuals, sample applications, or further technical support, please visitJTM-IC official websiteQuery.
