CXLB73326 is a synchronous buck-boost controller that supports input and output bidirectional power flow, with four MOSFETs integrated inside, with simple system structure and high efficiency. Its input/output voltage range is 2.7V-22V, sustainable working voltage of 25V, can effectively manage the charge and discharge process of 2~4 series batteries, support including 4.2V, 4.35V, 4.4V and other battery chemistry types.
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[ CXLB73326 ]"
With the continuous upgrading of portable electronic devices, smart homes, power tools and energy storage systems, efficient, flexible and safe power management solutions have become the key to product differentiation competition. As a highly integrated two-way synchronous buck-boost charging management chip, CXLB73326 not only supports the charge and discharge management of 2-4 batteries, but also has a wide range of voltage adaptation and rich programmable features, which is very suitable for the design requirements of modern high-performance battery-powered equipment. This article will comprehensively introduce the functional characteristics, working modes, design points and typical applications of the CXLB73326 to help engineers quickly understand and apply the chip and improve product development efficiency.
1. Chip Overview and Core Features
CXLB73326 is a synchronous buck-boost controller that supports input and output bidirectional power flow, with four MOSFETs integrated inside, with simple system structure and high efficiency. Its input/output voltage range is 2.7V-22V, sustainable working voltage of 25V, can effectively manage the charge and discharge process of 2~4 series batteries, support including 4.2V, 4.35V, 4.4V and other battery chemistry types.
Its main features include:
· Support bidirectional charging and discharging: VBUS charges to VBAT in charging mode, and VBAT discharges to VBUS in discharging mode;
· Wide voltage operating range: both VBUS and VBAT support 2.7V-22V;
· Integrated low internal resistance MOSFET:Q1/Q4 on-resistance 10mΩ,Q2/Q3 on-resistance 20mΩ;
· Complete charging management: support current elimination, constant current (CC), constant voltage (CV), charging termination and automatic recharging;
· Programmable: through the I2C interface can be set to charge and discharge current, output voltage, switching frequency, current limiting parameters;
· Comprehensive protection mechanism: including undervoltage protection, overvoltage protection, overcurrent protection, short circuit protection and overheat protection;
· Support battery NTC temperature detection to improve system safety;
· Miniaturized QFN 4 × 4-21 pin package for space compact design.
2. pin function and electrical parameters
There are 21 pins in the CXLB73326. The following are the functional descriptions of the key pins:
· VBUS: Charge and discharge power node, as input (charging) or output (discharging);
· VBAT: Battery connection terminal, as output (charging) or input (discharging);
· CE: Chip enable pin, high level active;
· SDA/SCL: I2C communication interface for register configuration;
· Trick: Battery number and voltage type setting pin;
· NTC: Battery temperature detection input;
· FB: Output voltage feedback pin in discharge mode;
· CSP/CSN: Current detection resistor connection end;
· COMP: Loop compensation pin, external RC network;
· SW1/SW2: Power inductor connection node.
The chip has good ESD protection capability (HBM ± 2kV), and the operating junction temperature range is -40°C to 150°C, which is suitable for various industrial and consumer applications.
Detailed explanation of 3. working mode
3.1. Charging mode (DIR = 0)
In the charging mode, the CXLB73326 manages the battery charging according to the classic flow elimination & rarr; constant current & rarr; constant voltage & rarr; cut-off & rarr; recharging process:
· current elimination charging: Enable when the battery voltage is lower than 60% of the set value, and pre-charge the battery with a small current;
· constant current charging: After the battery voltage exceeds the current elimination threshold, fast charging with the set current;
· constant voltage charging: When the battery voltage reaches 99% of the set value, it turns to the constant voltage stage, and the current gradually decreases;
· Charge cut-off: When the charging current is lower than the set termination current and lasts for a certain period of time, the chip stops charging;
· automatic refill: If the battery voltage drops below 97% of the set value, restart the charging process.
3.2. Discharge mode (DIR = 1)
In the discharge mode, the chip boosts or lowers the battery energy from the VBUS output, and the output voltage can be flexibly set by external resistor voltage division or I2C register. Support soft start, line loss compensation, dynamic output voltage adjustment and other functions to ensure stable output voltage and fast response.
3.3. Pass-through mode
The chip also supports the pass-through function from VBUS to VBAT. When the BATOVP condition is triggered, the system can bypass the DCDC conversion and directly supply power to the system to improve energy efficiency.
4. key design points
4.1. Inductance selection
It is recommended to use 4.7 μH-10 μH power inductors with saturation current higher than the estimated peak current and 20% margin. The inductance DCR value affects the efficiency of the system, and it needs to be selected reasonably according to the actual current and temperature rise requirements.
4.2. Input output capacitance
It is recommended to arrange multiple 22μF MLCC capacitors (X5R/X7R material) near VBUS and VBAT pins, and pay attention to their DC bias derating effect to ensure that the effective capacity meets the ripple requirements.
4.3. Current detection resistor
It is recommended to use a 10mΩ sampling resistor to take into account both accuracy and loss. If the efficiency requirements are extremely high, a smaller resistance value can be selected, but it is necessary to pay attention to whether the current detection accuracy still meets the requirements.
4.4. Loop Compensation
The COMP pin is externally connected to an RC network (typically 10kΩ 22nF) to stabilize the control system loop, and the user can fine-tune the compensation parameters according to the actual load and response requirements.
5. typical application scenarios
CXLB73326 are ideal for the following applications:
· High-power mobile power supply: Support two-way fast charging, up to 100W output;
· USB PD Device: Type-C interface power management for laptops and tablets;
· Power tools and drones: Efficient charge and discharge management of multi-section lithium battery pack;
· Smart speakers and home equipment: Charge and discharge control of the built-in battery system;
· Industrial test equipment and energy storage power supply: Flexible power supply scheme with wide voltage input and output.
6. I2C Interface and Register Configuration
CXLB73326 provides a rich set of programmable registers via the I2C interface (from address 0x 62), including:
· CSO_SET: Set the charge and discharge current limit;
· VBUS_SET_MSB/LSB: Set the discharge output voltage;
· GLOBAL_CTRL: Global control, including charge and discharge direction, DCDC switch, etc;
· FREQ_SET: Select the switching frequency (260kHz/500kHz/720kHz/920kHz);
· STATUS_1/2Read system status and fault information.
Users can flexibly configure these parameters through the MCU for dynamic power management, fault diagnosis and system optimization.
7. epilogue
As a highly integrated and high-performance bi-directional buck-boost charging management chip, CXLB73326 provides an ideal power solution for modern portable and energy storage devices with its wide voltage adaptability, flexible I2C configuration and comprehensive protection functions. Whether it is the pursuit of high efficiency, high power density, or the need for multi-cell battery management and intelligent control of the scene, the chip can meet the design requirements.
JTM-IC（jtm-ic.com) As a professional integrated circuit solution provider, we are committed to providing customers with high-performance, high-reliability chip products and complete technical support. For CXLB73326 samples, technical information or design assistance, please visit our official website or contact the technical support team.
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