CXLB73293 is a PFM boost charge control chip designed for dual Li-ion/polymer batteries. Its input voltage range is 3.0V-6.5V, supports up to 1.2A charging current, has built-in reference voltage source, inductor current detection, battery voltage detection and power MOSFET drive circuit, has few external components and simple circuit, greatly reducing the system cost and design complexity.
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[ CXLB73293 ]"
CXLB73293: high efficiency PFM boost dual-section lithium battery charging control chip depth analysis
In the context of the continuous pursuit of longer life and faster charging of various portable electronic devices, an efficient, compact and reliable battery charge management chip is particularly important. As a PFM boost type dual lithium battery charging control integrated circuit, CXLB73293 has become an ideal choice for POS machines, electric fans, audio and independent chargers with its wide input voltage of 3.0V-6.5V, maximum charging current of 1.2A, compact SOP8 package and other advantages. This article will introduce the technical characteristics, working principle, design points and typical applications of the CXLB73293 in depth, helping engineers to create a high-performance and high-reliability charging system.
1. Product Overview: High Performance in a Compact Package
CXLB73293 is a PFM boost charge control chip designed for dual Li-ion/polymer batteries. Its input voltage range is 3.0V-6.5V, supports up to 1.2A charging current, has built-in reference voltage source, inductor current detection, battery voltage detection and power MOSFET drive circuit, has few external components and simple circuit, greatly reducing the system cost and design complexity.
The chip is packaged in SOP8, which is small in size and suitable for portable devices with limited space. It has the input power adaptive function, which can intelligently identify the weak power adapter and adjust the charging strategy to ensure the stable operation of the system. In addition, the CXLB73293 also integrates battery overvoltage protection, status indicator output and other functions to fully guarantee charging safety.
2. core features: efficient, safe and intelligent
CXLB73293 excel in efficiency, security and smart management:
· Wide input voltage range: 3.0V-6.5V, compatible with multiple power inputs.
· High efficiency PFM control1MHz maximum switching frequency, improve system response and efficiency.
· Low power design: The static operating current is only 280 μA, and the off current is as low as 2 μA.
· Constant current/constant voltage chargingSupport full charge curve management to improve battery life.
· Intelligent status indicationCHRG pin output charging status, support external LED indication.
Multiple protection mechanisms: Including battery overvoltage protection, undervoltage protection, short circuit protection, etc.
· Lead-free environmental designRoHS compliant, halogen free.
3. application areas: widely adapted to a variety of electronic devices
The CXLB73293 applies to the following typical scenarios:
· POS machine and portable terminal: Provide stable and efficient charging support.
· Electric fans and small appliances: Support high power output and adapt to the needs of power equipment.
· Audio equipment: Low-noise design ensures that the sound quality is not disturbed.
· Independent charger: Less external components, low system cost, suitable for mass production.
How the 4. works: multi-stage charging and intelligent management
CXLB73293 uses a multi-stage charging strategy to ensure battery health and system safety:
4.1. Constant current charging stage
When the battery voltage is lower than 8.4V, the chip is quickly charged with the set current. The inductor current is set by an external sense resistor RCS, with upper and lower limits of 110mV/RCS and 16mV/RCS, respectively.
4.2. Quasi-constant voltage charging phase
When the battery voltage reaches 8.4V for the first time, the system turns to the quasi-constant voltage mode, and the charging current drops significantly to avoid overcharging and compensate for the internal resistance drop.
4.3. Charge cut-off and recharge
Charging ends when the battery voltage reaches 8.4V again; the charging cycle is automatically restarted when the voltage falls back to 7.9V.
4.4. Abnormal state protection.
· Battery low voltage/short circuit protection: The charging current is automatically reduced to prevent battery damage.
· Input undervoltage protection: Stop charging when the input voltage is lower than the threshold to ensure system safety.
5. Design Guide: Key Parameter Setting and Peripheral Selection
5.1. Charging current setting
The charging current is set by the sense resistor RCS between CSN and VCC, as follows:
5.2. Cut-off voltage adjustment
By connecting a resistor R1 in series between the BAT pin and the battery, the cut-off voltage can be adjusted upward:
The adjustment should not exceed 0.4V.
5.3. Peripheral component selection
· Inductance L1: 4.7 μH is recommended, and saturation current needs to be> 2A-3A.
· Input/output capacitance: 22 μF ceramic capacitor, low ESR, placed close to the chip.
· Diode D2: Low-dropout Schottky diodes such as SS24 or SS34 are recommended.
5.4. PCB Layout Recommendations
· The power path (VCC-LX-BAT) is as short and wide as possible to reduce loss and EMI.
· The input/output capacitor is close to the chip pin, the ground line is wide and short, and the star type ground is adopted.
· The current sense resistor RCS is as close as possible to the input filter capacitor.
6. Typical Problems and Solutions
· Charging current is small: Check whether the RCS resistance and input voltage are in the valid range.
· CHRG indicator is abnormal: Confirm the pin configuration and external circuit, check the battery connection status.
· obvious chip heating: Optimize heat dissipation design, reduce charging current or strengthen PCB heat conduction.
· Charging does not cut off: Check whether the BAT pin voltage reaches 8.4V and confirm the cut-off current setting.
7.Package and pin function
CSN (Pin 1):Charge current control terminal.
Adjust the charging termination voltage of the battery terminal upward, and the range of the charging termination voltage should not exceed 0.4V.
The typical battery end-of-charge voltage is determined by the following formula:
Vbat = 8.4 (0.007 x R1) (V) ( R1 unit is k)
LX (pin 5): switch terminal.
Internal power field effect transistor (MOSFET) connection point.
Eight, typical application schematic diagram
9. Conclusion: Choosing JTM-IC to Inject Lasting Power into Innovative Equipment
With its high integration, low power consumption, compact packaging and comprehensive charging management functions, the CXLB73293 has become a high-quality choice for dual lithium battery charging applications. As a JTM-IC (jtm-ic.com) One of its high-efficiency power management chips, we are committed to providing customers with high-performance, high-reliability solutions and professional technical support. If you are developing portable devices, independent chargers or small household appliances, please visit JTM-IC official website (jtm-ic.com) for more product information, design resources and sample support.
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