CXLB73280 is a highly integrated synchronous buck charging management chip with an input voltage range of 4.5V ~ 6V and a maximum charging current of 2.4A. It uses a 500kHz switching frequency and is up to 92% efficient at 5V input and 3.7V/2A output. The built-in power MOSFET greatly simplifies the peripheral circuit and reduces the BOM cost, which is very suitable for portable devices with limited space.
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[ CXLB73280 ]"
CXLB73280: an efficient intelligent 2.4A synchronous step-down lithium battery charging chip comprehensive analysis
With the rapid development of portable electronic devices, efficient, safe and intelligent battery charging solutions have become the core requirements of product design. As a synchronous buck charging management chip designed for 5V input, CXLB73280 has become an ideal choice for single-cell lithium battery charging applications with its high integration, high efficiency and comprehensive protection functions. This paper will analyze the technical characteristics, working principle and design points of the CXLB73280 in depth.
1. Product Overview
CXLB73280 is a highly integrated synchronous buck charging management chip with an input voltage range of 4.5V ~ 6V and a maximum charging current of 2.4A. It uses a 500kHz switching frequency and is up to 92% efficient at 5V input and 3.7V/2A output. The built-in power MOSFET greatly simplifies the peripheral circuit and reduces the BOM cost, which is very suitable for portable devices with limited space.
2. core features
2.1. High efficiency and high integration
· Synchronous buck architecture with up to 92% efficiency
· Built-in power MOS, no external diode required
· 500kHz Fixed Switching Frequency
2.2. Flexible charging current settings
· Set the charging current through the ISET pin external resistor
· Support 1.0A, 1.5A, 2.0A, 2.4A multi-gear selection
2.3. Comprehensive temperature protection
· Support NTC resistance to detect battery temperature
· 5-stage charging management, compatible with JEITA standard
· Chip over-temperature protection (140 ℃ shutdown)
2.4. Intelligent LED status indication
· Dual LED output, support charging status display
· LED1 supports constant current output without series current limiting resistor
· Intelligent prompt for abnormal state
2.5. Multiple protection mechanisms
· Input undervoltage/overvoltage protection
· Battery overcharge protection
· ESD 4KV Protection
· Standby power <2μA
3. typical application scenarios
CXLB73280 are widely used in all kinds of single lithium battery power supply equipment:
♦ Portable Audio Equipment
· Bluetooth speaker, TWS headset charging bin
♦ Intelligent wearable equipment
· Smart watch, bracelet charging management
Household electronic products
· Hand-held fan, portable lamp, electric toy
Detailed explanation of key 4. technology
4.1. Charging current setting
The charging current is set through the ISET pin external resistor RISET, and the specific relationship is as follows:
| RISETResistance | Charging current |
|---|---|
| 1.4kΩ | 2.4A |
| 2.4kΩ | 1.5A |
| 4.3kΩ | 1.0A |
| NC(≥120kΩ) | 2.0A |
Calculation formula: ICC(A) = 0.35 2.75/RISET(kΩ)
4.2. NTC temperature protection
CXLB73280 accurate temperature monitoring via the NTC pin:
· Low temperature protection:<0°C Stop charging
· medium low temperature: 0-10°C current halved
· Normal range: 10-45°C full-speed charging
· medium high temperature: 45-60°C lower full voltage
· High temperature protection:>60°C Stop charging
When the NTC function is not required, the NTC pin can be grounded through a 10kΩ resistor.
4.3. Charging process management
Complete trickle/constant current/constant voltage three-stage charging:
· trickle charge: VBAT<3.0V, the current is 1/5 of the constant current value
· constant current charging: VBAT>3.0V to set current charging
· constant voltage charging: VBAT & asymp;4.2V, constant voltage, gradually decreasing current
5. LED status indication
CXLB73280 provides intuitive status indication:
| Working status | LED1 | LED2 |
|---|---|---|
| Charging | Bright | Extint |
| Full | Extint | Bright |
| Abnormal state | Flashing | Flashing |
| Battery not connected | alternating flashing | alternating flashing |
Abnormal states include: input over-voltage, abnormal temperature, chip over-temperature, etc.
Key Points of 6. PCB Design
6.1. Heat dissipation design
· ESOP-8 package bottom EPAD must be well grounded
· It is recommended to arrange multiple vias under EPAD to the formation
· Keep the copper width of the power path sufficient
6.2. Component Selection Recommendations
· Inductance: 2.2 μH, saturation current> 3.5A,DCR<20mΩ
· Input/output capacitance: 10μF ceramic capacitor, placed close to the pin
· NTC resistance: 10kΩ,B = 3380 (if not required, replace with 10kΩ resistor)
6.3. layout optimization
· VIN, BAT pin capacitors as close as possible to the chip
· LX Node Area Minimization to Reduce EMI
· Keep analog ground (GND) separate from power ground
7. efficiency performance
The measured data shows the excellent performance of the CXLB73280 under different working conditions:
· 1A charging: efficiency> 90%
· 2A charging: efficiency> 91%
· 2.4A charging: efficiency> 90%
The high efficiency allows the chip to maintain low temperature operation when charging at 2.4A.
8. Package and Pin Function Description
Nine, typical principle circuit diagram and BOM
10. Summary
With its high integration, high efficiency, comprehensive protection function and flexible configuration options, the CXLB73280 has become an excellent solution for single-cell lithium battery charging applications. Whether it is consumer electronics, smart wear or household appliances, its excellent performance can provide safe and reliable charging protection for the product.
If you need to obtain CXLB73280 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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