CXLB73282 is a 800kHz fixed frequency synchronous buck charging IC, the input voltage range is 4.0V ~ 6.0V, the typical application is 5V adapter. The built-in power MOSFET eliminates the need for an external freewheeling diode, greatly simplifying peripheral circuit design. The chip supports an adjustable output current of up to 3.5A, and the charging efficiency is as high as 92%, which effectively reduces system heating and improves overall reliability.
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[ CXLB73282 ]"
CXLB73282: An efficient 3A lithium battery charging chip for 5V adapter
With the rapid development of portable electronic devices, efficient, safe and compact battery charging management scheme has become the core of product design. As a 3A lithium-ion battery synchronous buck charging chip designed for 5V AC adapter, CXLB73282 is widely used in mobile phones, tablet computers, digital cameras, Bluetooth speakers and other devices with its high integration, high efficiency and comprehensive protection functions. This article will comprehensively analyze the performance advantages and use points of the CXLB73282 from the aspects of technical characteristics, working principle, application design and thermal layout.
1. Product Overview
CXLB73282 is a 800kHz fixed frequency synchronous buck charging IC, the input voltage range is 4.0V ~ 6.0V, the typical application is 5V adapter. The built-in power MOSFET eliminates the need for an external freewheeling diode, greatly simplifying peripheral circuit design. The chip supports an adjustable output current of up to 3.5A, and the charging efficiency is as high as 92%, which effectively reduces system heating and improves overall reliability.
2. core features
2.1. High efficiency and high precision
· Switching frequency: 800kHz
· Charging efficiency:>92%
· Output voltage accuracy: ± 1% (typical 4.35V)
2.2. Flexible current and voltage settings
· Set the charging current through the PROG pin external resistor (200Ω ~ 1kΩ)
· Support current elimination, constant current, constant voltage three-stage charging management
· Adjustable float voltage via external resistor to compensate for line losses
2.3. Comprehensive system protection
· Input undervoltage/overvoltage protection
· Battery temperature monitoring (via NTC)
· Output short circuit protection
· Chip over-temperature and down-current protection
· Anti-backfilling and automatic recharging
2.4. Intelligent Status Indication
· Dual open-drain output: NCHRG (charging) and NSTDBY (full)
· Support red and green two-color LED indication, intuitive display of charging status
2.5. Low power design
· Standby current: Typical 70μA
· Battery current in shutdown mode:<2μA
3. typical application scenarios
Mobile phones and tablets
The CXLB73282 supports 3A high current charging, which can quickly replenish power for smart phones and tablet devices. Its high efficiency and temperature protection function ensure safe and reliable charging process.
Digital camera and portable audio
In video and audio equipment, the battery capacity is usually large. CXLB73282 constant-current constant-voltage charging mechanism with NTC temperature monitoring effectively extends battery life.
GPS devices and electronic dictionaries
Such devices require high power consumption and charging stability. CXLB73282 low standby current and adaptive input current control are ideal for such applications.
4. Critical Circuit Design Guide
4.1. Charging current setting
Charging current IBATRESISTANCE R BY PROG PINPISet, the common resistance and current corresponding relationship is as follows:
| RPI | IBAT |
|---|---|
| 1.08kΩ | 1A |
| 412Ω | 2A |
| 249Ω | 3A |
| 210Ω | 3.5A |
4.2. Temperature monitoring settings
4.2.1 TS pin connected to NTC thermistor for battery temperature monitoring
4.2.2 Protection threshold:
· Low temperature:<45% VIN
· High temperature:>80% VIN
4.2.3 If temperature monitoring is not required, connect TS to VCC
4.3. float voltage compensation
In order to compensate the internal resistance of the battery and the line voltage drop, the external resistor R can be used.PVFine adjustment float voltage:
Recommended RPV= 1kΩ as the default configuration.
4.4. Typical application circuit schematic diagram
4.5. Expand applicationCircuit schematic
5. PCB Layout and Thermal Design
Since the CXLB73282 is packaged in SOP8, the heat dissipation capability directly affects the continuous output capability of the maximum charging current. Here are the key layout recommendations:
5.1. Thermal pad design：
· Set 2.5mm × 6.5mm copper pads at the bottom of the chip
· Arrange 4 Φ1.2mm via holes with a hole spacing of 1.6mm
· When soldering, tin is poured from the back to ensure good contact between the chip heat sink and the PCB
5.2. Power Path Design：
· 22 μF Ceramic Capacitor Arrangement Nearby VCC and BAT Pins
· Power inductance with rated current ≥ 4A and low internal resistance (2.2μH ~ 10μH recommended)
5.3. Thermal Management：
· Avoid placing other heat sources around the charging IC
· Make full use of internal power layer and back copper heat dissipation
Detailed explanation of 6. protection mechanism
6.1. input adaptive protection
When the input voltage is lower than VINSL(typically 4.65V), the chip automatically reduces the charging current to prevent the adapter from overloading.
6.2. Short circuit and current limiting protection
· Input Current Limit: Peak 4.5A
· Output short circuit protection: output voltage <2.2V, the input current limit to 100mA
6.3. over-temperature protection
· Automatic downflow when junction temperature exceeds 145 ℃
· Stop charging when temperature> 150 ℃
6.4. Undervoltage lockout (UVLO)
When the input voltage is lower than 4V, enter the shutdown mode, and restart after the voltage is restored and higher than the battery voltage 120mV.
7. Status Indication and Fault Diagnosis
| Charging state | NCHRG (red light) | NSTDBY (green light) |
|---|---|---|
| Charging | Bright | Extint |
| Full | Extint | Bright |
| Fault * | Extint | Extint |
* Faults include: abnormal temperature, battery not connected, input undervoltage, etc.
8. to expand the application: white LED driver
CXLB73282 can also be used to drive white LED (such as 3W ~ 11W). When the input is 6V (such as 4 dry batteries), the chip works in constant current mode, and the output current isPISettings for portable lighting and backlighting systems.
9. Package and Pin Function Description
mode, the current of the BAT pin will be less than 2uA.
PROG (pin 2): Maximum charging current setting, resistor value between 200Ω ~ 1kΩ.
NSTDBY (pin 3): charging completion indicator terminal. When the battery charging is completed, the pin is pulled low by the internal switch, indicating that the charging is complete, no
The pin is then in a high impedance state.
NCHRG (pin 4): charging status indication terminal. When the charger is charging the battery, this pin is pulled low by the internal switch, indicating that the charging is being
proceed, otherwise the pin is in a high impedance state.
TS (Pin 5): Battery temperature sensing input. The TS pin is connected to the output of the battery's NTC sensor. If the voltage at the TS pin is less than the input
45% of the voltage or more than 80% of the input voltage, which means that the battery temperature is too low or too high, the charging is suspended. If the TS is directly connected to the VCC terminal,
The pool temperature detection function is canceled, and other charging functions are normal. If the TS is directly connected to GND, the standby mode is entered and charging is terminated.
BAT (pin 6): Battery voltage detection terminal. A resistor is connected in series between the positive terminal and the pin of the battery to adjust the full voltage of the battery. The chip is
When the operation is prohibited or the sleep mode, the leakage current of the BAT pin is less than 2uA.
GND (pin 7): Power supply ground.
LX (pin 8): Built-in power MOSFET connection point. LX is the CXLB73282 current output connected to the external inductor as the battery charging current input
End.
TenSummary
With its high integration, high efficiency, comprehensive protection functions and flexible design options, the CXLB73282 has become an ideal choice for lithium battery charging management in the 5V adapter scenario. Whether in consumer electronics, industrial equipment or portable instruments, its excellent performance and reliability can enable products.
If you need to obtain CXLB73282 samples, technical information or apply for design support, please visitJTMIC official website (jtm-ic.com）Or contact our technical support team.
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