CXLB73295 is a synchronous boost charge management chip designed for three series Li-ion/polymer batteries. Its input voltage range is 3.0V-9.5V wide, supports 5V adapter or PD 9V input (requires decoy chip), and the maximum charging current can reach 2A. All power MOSFETs are integrated inside the chip without external diodes, which greatly simplifies the design of peripheral circuits.
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[ CXLB73295 ]"
Introduction
In modern portable electronic devices, lithium batteries are widely used because of their high energy density and long cycle life. For the charging management of multiple series lithium batteries, CXLB73295, as a high-performance synchronous boost charging chip, has become an ideal choice for mobile power supply, intelligent door lock, game console and other products with its high integration, high efficiency and multiple protection mechanism. This article will analyze the functional characteristics, application design and selection suggestions of the CXLB73295 in depth to help engineers better apply the chip and improve product performance and reliability.
1. CXLB73295 Overview
CXLB73295 is a synchronous boost charge management chip designed for three series Li-ion/polymer batteries. Its input voltage range is 3.0V-9.5V wide, supports 5V adapter or PD 9V input (requires decoy chip), and the maximum charging current can reach 2A. All power MOSFETs are integrated inside the chip without external diodes, which greatly simplifies the design of peripheral circuits.
The CXLB73295 has four charging modes:
· Short circuit charging: Support safe charging of 0V batteries;
· Current elimination charging: Recovery of deeply discharged batteries;
· Constant current charging: Realize fast charging;
· Constant voltage charging: Ensure that the battery is fully charged and not charged.
The charging cut-off current is 1/10 of the set value, and supports the automatic recharging function to ensure that the battery is always kept in the best condition.
Main characteristics of 2.
2.1. High efficiency charging
The peak efficiency is as high as 96%, and the heavy load efficiency exceeds 90%, which effectively reduces heat generation and improves charging speed.
2.2. Flexible parameter settings.
· The charging current is programmed through an external resistor;
· Full voltage support 12.6V, 12.9V, 13.05V, 13.2V four adjustable;
· Support NTC temperature detection to ensure charging safety.
2.3. Comprehensive protection mechanisms
· Input overvoltage/undervoltage protection;
· Battery overvoltage, short circuit, abnormal temperature protection;
· Programmable charging timeout protection;
· 160 ℃ overheat shutdown.
2.4. Intelligent control and indication
· Support single/dual LED charging status indication;
· The SYSRT pin can control the rear stage load switch;
· The EN pin supports external shutdown for easy system management.
2.5. Encapsulation options
· QFN3 × 3-16 (ultra-small volume)
· ESSOP10 (excellent heat dissipation, & theta;JA = 43.4 ℃/W)
3. typical application scenarios
CXLB73295 is widely used in:
· Mobile power supply: Support high current fast charging, high efficiency;
· Intelligent door lock: low temperature charging does not hurt the battery;
· Portable game machine(such as PSP, NDS): stable power supply, strong endurance;
· Multimedia equipment(MP3/MP4, mobile phones): Charging is safe and efficient.
4. Critical Circuit Design Guide
● Boost output pin BD. The 10μF voltage stabilizing ceramic capacitor should be as close to the chip as possible, and the loop from BD to GND should be as short as possible. This capacitor has the highest priority.
High, can refer to the PCB layout for example.
● NTC resistance is generally located inside the battery, for the convenience of display, the dashed box is the battery pack. 100K with B value of 4250K is required in typical NTC applications
The NTC resistor with resistance value is connected in parallel with R2(150K) resistor and then connected in series with R1(57.6K) resistor to VDD pin. This collocation can ensure that the battery is at 0 ℃
Normal charging at ~ 60 ℃. If other combinations are used, refer to the NTC voltage for each temperature threshold interval given in the NTC function explanation on page 13.
Design or consult our FAE.
● For the bottom ePad GND pin, a larger copper clad area should be used to connect to the PCB ground plane, which helps to minimize PCB conduction loss and
Thermal stress to prevent the charging current from dropping due to high chip temperature.
● LED indicator shall be connected with current limiting resistor to VDD when used, and 3K is recommended. If you need to use the dual-lamp scheme, you must configure it according to the color of the LED lights in the figure. Please purchase
Buy LED lights of corresponding colors for experiments. When charging, the red light is on and the blue light is off; when full, the blue light is on and the red light is off; when abnormal, the red light and blue light flash alternately.
4.1. Charging current setting
Through the ICHG pin access resistor RICHG to set the charging current, the formula is as follows:
VICHG is 1V in constant current mode. For example, when RICHG = 1K, the charging current is 1A.
4.2. Output voltage setting
Set the full voltage via the CV pin external RCV resistor:
· RCY≤ 2.5K:12.6V
· RCY = 7.5K：12.9V
· RCY = 25K：13.05V
· RCY ≥ 75K：13.2V
4.3. NTC temperature detection
Using 100K NTC(B = 4250K) and R1 = 57.6K, R2 = 150K to form a partial pressure network, normal charging at 0 ℃ ~ 60 ℃ can be realized. If NTC is disabled, two 10K resistors can be used to divide the voltage at the NTC pin to 50% VDD.
4.4. Adaptive input limit.
The input voltage threshold is set through the ILIM pin, and the charging current is automatically adjusted when an input voltage drop is detected to avoid overloading the adapter.
5. PCB Layout Recommendations
· Power loop minimization: LX, BD, BAT and other large current paths should be wide copper traces;
· Nearby placement of capacitors: CBD(10μF) must be closest to the BD pin and CBAT(20μF) close to BAT;
· Heat dissipation design: The bottom ePad should be connected to a large area of copper cladding and perforated for heat dissipation;
· signal isolation: ICHG, TIM, NTC and other signal lines are far away from the LX switch node and SGND is used.
The layout design of the CXLB73295 boost lithium-ion battery charger is relatively simple. In order to obtain the best efficiency and minimize noise problems, we should
以下组件放置在 IC 附近： CSVIN、CBAT、CBD、CBST(CBD 电容必须靠近引脚优先级最高)。：
● The power loop must be as short as possible.
● Output circuit CBD capacitor is close to chip BD and PGND pins; CBST capacitor is a bootstrap capacitor that needs to be close to chip pin BST;CBAT capacitance as far as possible
Close to chip pins BAT and PGND pins.
● ICHG, CTIM, RCV, NTC and other digital signals try to use SGND, while staying away from LX signals to reduce noise interference.
● Large PCB copper clad areas should be used for high current paths, including LX,PGND pins and bottom thermal pads. This helps to minimize
PCB conduction loss and thermal stress.
● To minimize via conduction loss and reduce module thermal stress, multiple vias should be used to interconnect the top layer and other power or ground layers
(Chip bottom pad plus through-hole window to help chip heat dissipation to improve performance).
● RNTC is a thermistor, which is used to detect the temperature of the battery. It is generally located inside the battery. If it is on the PCB board, it is recommended to stay away from the chip and inductor.
Thermal elements.
● BD capacitor must be close enough to the chip. 1206 capacitor can be used to connect across BD and PGND pins so that LX can penetrate through the bottom of the capacitor.
6. purchase and technical support
JTM-IC（jtm-ic.com) as the official authorized supplier of CXLB73295, providing a full range of packaging options and professional technical support. We can provide:
· Sample application and batch supply;
· Reference design and PCB review;
· FAE online Q & A and customized services.
Seven, package and pin function
Eight, the conclusion
With its high integration, high efficiency and multiple protection functions, the CXLB73295 has become the preferred chip for the three-section lithium battery charging scheme. Whether in mobile power, smart door locks or portable entertainment devices, its stable and reliable performance can significantly improve the user experience. Welcome to visitJTM-IC official websiteLearn more, access the data sheet, design resources, and sample request support.
Nine, the relevant chip selection guide download ► More similar products....
