CXLB73272 is a linear charge management chip based on constant current/constant voltage (CC/CV) architecture, specially designed for single lithium ion or lithium polymer batteries. Its input voltage range covers 4.0V to 6.0V and can withstand up to 28V instantaneous voltage, effectively coping with voltage fluctuation of power adapter or USB port. The chip adopts the internal PMOS architecture and integrates the anti-reverse charging function without external discrete diodes, greatly simplifying the circuit design and saving the layout space.
-
[ CXLB73272 ]"
Among all kinds of portable electronic devices, safe, efficient and stable battery charging management solutions are the core to ensure product performance and user experience. CXLB73272 as a complete single lithium ion/lithium polymer battery linear charging chip, with its input voltage up to 28V, 1A programmable charging current, comprehensive temperature protection mechanism and simple external component requirements make it an ideal choice for applications such as mobile power supply, digital camera, portable stereo, GPS equipment, etc. This paper will deeply analyze the technical characteristics, working principles and design points of CXLB73272 to help engineers realize more reliable and efficient charging system design.
I. Product Overview
CXLB73272 is a linear charge management chip based on constant current/constant voltage (CC/CV) architecture, specially designed for single lithium ion or lithium polymer batteries. Its input voltage range covers 4.0V to 6.0V and can withstand up to 28V instantaneous voltage, effectively coping with voltage fluctuation of power adapter or USB port. The chip adopts the internal PMOS architecture and integrates the anti-reverse charging function without external discrete diodes, greatly simplifying the circuit design and saving the layout space.
CXLB73272 is packaged in cooling fin with DFN3x3-8L at the bottom, with excellent thermal performance and compact size, which is very suitable for portable devices with limited space.
II. Core functions and features
2.1. High-precision charging management and programmable current
·The charging voltage is fixed to 4.2V with an accuracy of ± 1%, which meets the safety charging requirements of lithium batteries.
·The charging current is set by the external resistor (RPROG) of the PROG pin. The maximum charging current is 1000mA.
·Charging current estimation formula:
Where VPROG1V in constant current phase
2.2. Multiple charging status indication
·NCHRG pin: output low level during charging
·NSTDBY pin: output low level after charging
Supports no battery or fault status prompts to facilitate system monitoring and user interaction.
2.3. Comprehensive security protection mechanism
2.3.1 input undervoltage/overvoltage protection: undervoltage locking threshold 3.8V, overvoltage protection threshold 6.3V
2.3.2Temperature Protection:
·When the chip junction temperature exceeds 145 ℃, the flow automatically drops.
·Supports external NTC battery temperature detection and suspends charging beyond the set range.
2.3.3 Soft start function: limit surge current during startup to improve system reliability
2.3.4Automatic recharge: automatically restart the charging cycle when the battery voltage is lower than 4.10V
2.4. Low power consumption design
·Battery leakage current <5% A in sleep mode
·The input current is about 60 μA in shutdown mode.
·Suitable for power-sensitive portable devices and standby charging set
3. Typical application scenarios
·Mobile Power and Power Bank: supports 1A fast charging, integrated anti-reverse charging and status indication
·Digital camera and portable stereo: high-precision voltage control extends battery life
·GPS equipment and electronic dictionary: low standby power consumption suitable for long standby
·All kinds of portable devices/customized Chargers: compatible with USB and adapter power supply, flexible design
IV. Key Design Guidelines
4.1. Charging current setting
Select RPROG resistance based on the target charging current:
·RPROG=1.2kΩ → IBAT= 1000mA
·RPROG=2.4kΩ → IBAT= 500mA
We recommend that you select a resistor with accuracy ≥ 1% to ensure current accuracy.
4.2. Thermal Management design
DFN package depends on PCB heat dissipation. We recommend that you:
·At the bottom of the chip, a copper cover welding plate ≥ 1.5 × 2.0mm is arranged.
·Set more than 2 heat dissipation holes & phi;0.8mm, and fill tin on the back to enhance heat conduction
·Avoid arranging other heat sources around the charging IC
4.3. Temperature detection configuration
4.3.1 Use 10 kOhm NTC thermistor (B = 3380K-3950K)
4.3.2 protection threshold:
·VNTC < 0.15V & rarr; If the temperature is too high, the charging is suspended.
·VNTC > 1.2V & rarr; If the temperature is too low, suspend charging.
4.3.3 if temperature detection is not enabled, the NTC pin can be suspended or connected to the ground with a resistance> 1 Mohm.
4.4. Status indicator circuit
·NCHRG and NSTDBY are open-drain outputs, and external pull-up resistor is required.
·Can drive LED or connect MCU for status detection and logic control
V. Brief introduction of working principle
CXLB73272 strictly follow lithium battery charging specifications:
·Discharge charging: when VBAT <2.5V, restore the deep discharge battery with a small current (about C/10)
·Constant current charging: After VBAT> 2.5V, charge quickly with set current
·Constant voltage charging: when VBAT approaches 4.2V, the voltage is constant and the current gradually decreases.
·Charging termination: automatically stops when the current drops to 1/10 of the set value and enters standby mode
·Automatic recharge: restart charging when the battery voltage drops below 4.10V
VI. Suggestions on heat dissipation and power management
To maintain high charging current and control temperature rise:
·The adapter with small high voltage difference (such as 5V) is preferred.
·Part of the power consumption can be shared by series small resistance resistor (such as 0.25 Ω) to improve the thermal adjustment current.
·Make full use of the internal copper layer and via hole heat dissipation of multilayer board in actual layout
VII. Selection and technical support
JTM-IC (official website:jtm-ic.com) provide complete technical support and sample services for CXLB73272, including:
·Data Manual, typical application schematic diagram and PCB layout reference
·Suggestions on thermal design and current configuration
·Customized option consultation and batch supply guarantee
8. Packaging and pin functions
Pin description
NTC (pin 1):Battery temperature detection input terminal. Connect the pin to the output of the NTC sensor of the battery. If the voltage of the NTC pin is small
At 150mV or more than 1.2V, it means that the battery temperature is too high or too low, and the charging is suspended. If the NTC is suspended or connected to a resistor above 1 Mohm
To the ground, the battery temperature detection function is canceled, and other charging functions are normal.
PROG (pin 2):Constant current charging current setting and charging current monitoring terminal. Connecting an external resistor from PROG pin to the ground can charge
The current is programmed. In the pre-charging stage, the voltage of this pin is limited to 0.2V; In the constant current charging stage, the voltage of this pin is fixed
1v. In all modes of the charging state, measuring the voltage of the pin can estimate the charging current according to the following formula:
IBAT= VPROG/RPROG*1200
GND (pin 3):Power supply ground.
VCC (pin 4):Input voltage positive input terminal. This pin voltage is the working power supply of the internal circuit. When the voltage difference between VCC and BAT pins is less
At 30mV, CXLB73272 will enter the shutdown mode with low power consumption, and the current of BAT pin will be less than 2uA.
BAT (pin 5):Battery connection terminal. Connect the positive end of the battery to this pin. BAT pin
The leakage current is less than 2uA. BAT pins provide charging current and 4.2V limiting voltage to the battery.
NSTDBY (pin 6):The rechargeable battery full indicator of the open drain output. When the battery is full, the pin is pulled to a low level by the internal switch,
Otherwise, the pin is in the high resistance state.
NCHRG (pin 7):The charging status indicator of the open drain output. When the charger charges the battery, the pin is pulled low by the internal switch.
Level, indicating that charging is in progress; Otherwise, the pin is in the high resistance state.
NCE (pin 8):Chip Enable input. Input low level will make the chip in normal working state; Input high level will make the chip in disabled state
Stop charging status. The NCE pin can be driven by TTL level or CMOS level.
IX. Schematic diagram of typical applications
Ten, Conclusion
CXLB73272 has become the preferred solution for charging management of single lithium battery due to its high integration, high reliability and flexible programmable capability. Whether in consumer electronics or industrial equipment, the chip can provide efficient charging performance on the premise of ensuring safety. Welcome to the JTM-IC official website for more technical resources and product information. We will wholeheartedly provide you with professional power management solutions.
Eleven, download the relevant chip selection guide -More similar products....
