CXLB73332 is a single lithium ion battery management chip with linear charging architecture. Its input voltage range (4.25V ~ 6.5V) is perfectly compatible with USB power supply standards, without external MOSFETs, detecting resistance or blocking diode greatly simplifies the system design. The chip uses a compact SOT23-5L package, which is suitable for portable products with limited space and is an ideal choice to replace the traditional discrete charging scheme.
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[ CXLB73332 ]"
CXLB73332: high-efficiency single lithium battery linear charging management chip specially built for portable devices
In today's mobile Internet era, the battery life and charging experience of portable electronic devices directly affect user satisfaction. CXLB73332 as a perfect monolithic lithium ion battery constant current/constant voltage linear power management chip, with its small size, high integration, low power consumption and excellent thermal management performance, it has become a mobile phone, PDA, MP3, ideal charging solution for Bluetooth devices and other products. This paper will deeply analyze the technical characteristics, working mode, design key points and application examples of CXLB73332 to provide engineers with one-stop design reference.
I. Product overview and market positioning
CXLB73332 is a single lithium ion battery management chip with linear charging architecture. Its input voltage range (4.25V ~ 6.5V) is perfectly compatible with USB power supply standards, without external MOSFETs, detecting resistance or blocking diode greatly simplifies the system design. The chip uses a compact SOT23-5L package, which is suitable for portable products with limited space and is an ideal choice to replace the traditional discrete charging scheme.
Target application areas include:
·Consumer electronics: smartphones, tablets, portable media players;
·Wireless devices: Bluetooth headset, speaker, mouse, keyboard;
·Handheld devices: PDA, barcode reader, portable measuring instruments;
·Smart wear: watch, bracelet, health monitoring equipment.
II. Core functions and product advantages
2.1. Complete charging management process
CXLB73332 supports complete charging stage: Trickle charging (battery voltage <2.9V)& rarr; Constant current charging & rarr; Constant voltage charging (4.2V ± 1%)& rarr; automatic Termination (current drops to 1/10 of the set value). The whole process is safe and efficient without external intervention.
2.2. Programmable charging current
The external resistor RPROG can flexibly set the charging current up to 500mA to meet the charging requirements of batteries with different capacities. The current setting formula is:
The typical value of VPROG is 1.0V.
2.3. Excellent thermal management and protection mechanism
·Thermal feedback regulation: automatically reduce the charging current when working at high ambient temperature or large current to prevent chip overheating;
·Input undervoltage lockout: pause charging when the input voltage is lower than 3.8V to protect the front-end power supply;
·Intelligent Sleep: After the input power is removed, the battery leakage current is less than 2μa, extending the standby time.
2.4. Visual indication of charging status
CHRG pin is open-drain output, which can directly drive LED or connect to MCU to display charging status in real time:
·Charging: output low level
·Charging completed/abnormal: high resistance state
·Battery not connected: LED flashing prompt
3. Detailed explanation of pin functions
| Pin | Name | Function description |
|---|---|---|
| 1 | CHRG | Charging status indicator output, open drain structure, need to be pulled up externally |
| 2 | GND | System Grounding |
| 3 | BAT | Battery connection terminal, internal integrated charging current output and voltage detection |
| 4 | VIN | Power input (4.25V ~ 6.5V), external ≥ 1μF capacitor is required |
| 5 | PROG | Charging current programming and enabling control, connecting resistance to ground setting current |
Multifunctional design of PROG pin:
·Connecting resistance to ground: set charging current
·Suspended or voltage> 1.21V: Enter the shutdown mode, and the input current drops to 25μA
·Voltage> 2.4V: 1.5mA pull-up current can be provided
IV. Workflow and status transition
4.1. Normal charging process
4.1.1 check the battery voltage, if <2.9V enters trickle charging (about 1/5 of the set current)
4.1.2 The voltage rises above 2.9V and enters the constant current charging stage.
4.1.3 when the voltage approaches 4.2V, it is switched to constant voltage charging, and the current gradually decreases.
4.1.4 when the current drops to 1/10 of the set value, the charging will automatically terminate.
4.2. Low Power management
·Standby mode: after charging, the input current is about 200μA
·Shutdown mode: When the PROG pin is suspended or the input voltage is abnormal, the input current drops to 25pa A.
·Sleep mode: When VIN = 0V, the battery current is only 1 ~ 2μA
4.3. Automatic recharging
After the battery voltage drops more than 100mV (typical value), the system automatically restarts the charging cycle to ensure that the battery always maintains a high battery state.
V. Typical application circuit design
5.1. Basic application circuit:
VIN ─┬─── C1(4.7μF) ── GND
──-pin 4
── RLED ── LED ── CHRG (pin 1)
PROG (pin 5) ── RPROG ──gnd
BAT (pin 3) ─────c2 (10μf) ──gnd
── battery
5.2. Component selection suggestions:
5.2.1.C1:4.7 μF ceramic capacitor, close to VIN pin
5.2.2.C2:10 LEDs F ceramic capacitor, close to BAT pin
5.2.3.RPROG: Select according to the required charging current
·500mA:RPROG & asynp; 2 kΩ(1% accuracy)
·100mA:RPROG & asynp; 10kΩ(1% accuracy)
5.2.4RLED: calculated based on LED current, usually 1 to 5 kOhm
VI. Electrical characteristics and performance parameters
6.1. Absolute maximum rating
·Input voltage range:-0.3V to 7V
·BAT pin voltage:-0.3V to 7V
·Operating temperature:-40℃ ~ 85℃
·Storage Temperature:-65 ℃ to 125 ℃
·Maximum power consumption: 250MW (TA = 25℃)
6.2. Key performance parameters (VIN = 5V,TA = 25℃)
·Float-charge pressure accuracy: 4.2V ± 1%
·Trickle charge threshold: 2.9V
·Input undervoltage lockout: 3.8V (with 200mV hysteresis)
·Charging termination ratio: the current drops to 10% of the set value.
·PROG pin voltage: 1.0V (constant current phase)
·CHRG pin pull-down current: 20μa (typical)
VII. PCB layout and thermal design guide
7.1. Priority of layout
·The input and output capacitors are as close as possible to the corresponding pins of the chip.
·PROG programming resistor is close to the chip, and the wiring is short and thick
·Chip GND pin is directly connected to ground plane
7.2. Heat dissipation treatment
·Add heat dissipation vias under and around the chip
·Avoid arranging other heating components directly below the chip
·If necessary, a small amount of copper foil area can be added to assist heat dissipation.
7.3. Noise suppression
·The power line should be as wide and short as possible.
·Sensitive signal line away from high frequency or switching signal
·Ensure the integrity of the ground plane and reduce the noise of the ground bomb
8. Common Application problems and solutions
8.1. The charging current is too small
·Check RPROG resistance value and accuracy
·Measure whether the PROG pin voltage is about 1.0V
·Check whether the input voltage is sufficient (>4.25V)
8.2. Chip temperature rise is too high
·Check whether the charging current is too large
·Optimized PCB heat dissipation design
·Check whether the ambient temperature is within the specification range
8.3. Abnormal charging indicator light
·Confirm that the LED and current limiting resistor are connected correctly.
·Check the peripheral circuit of CHRG pin
·Measure whether the battery voltage is normal
8.4. Unable to enter the charging state
·Check whether the input voltage is above 30mV of the battery voltage
·Confirm whether the PROG pin is properly grounded
·Check whether the battery is reverse connected or damaged
IX. Selection and extended application
CXLB73332 is suitable for most single lithium ion/polymer battery charging scenarios. For higher charging current, multiple batteries or more complex functions,jtm-ic.comProvide a full range of power management solutions, welcome to consult. The chip can also work with MCU to realize:
·Intelligent charging control (adjust current according to temperature and time)
·Charging status monitoring and reporting
·Battery Health Assessment
·Optimal management of system power consumption
10. Conclusion
With its high integration, excellent temperature adaptability, complete protection function and simple peripheral circuit, CXLB73332 provides a reliable, efficient and economical battery charging solution for portable electronic devices. Whether pursuing light & fashionable consumer electronics products or focusing on stable and reliable industrial equipment, the chip can meet the design requirements and enhance the overall competitiveness of products.
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