CXLB73313 is a Ni-MH battery charging management chip with PWM buck architecture, with a wide input voltage range of 2.7V-6.5V, suitable for a variety of power supply environments, including USB adapters, solar panels, etc. The chip through constant current and maintain charging two-stage intelligent management, with internal timer and voltage detection mechanism to ensure that the battery is fully charged and effectively extend its service life. Its eSOP-8 package is small in size and has good heat dissipation, which is very suitable for portable devices with limited space.
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[ CXLB73313 ]"
CXLB73313 single Ni-MH battery efficient charging management IC comprehensive analysis
With the popularity of portable electronic devices, smart toys, car models and other products, efficient and safe battery charging management scheme has become a key link in the design. As a fixed off-time, step-down PWM charging management integrated circuit designed for single-cell Ni-MH battery, CXLB73313 is widely used in all kinds of low-voltage charging scenarios with its advantages of high integration, simple peripheral and perfect functions. This article will systematically introduce the characteristics, working principle, design points and typical applications of the CXLB73313 to help engineers achieve efficient and reliable charging system design.
1. CXLB73313 Overview
CXLB73313 is a Ni-MH battery charging management chip with PWM buck architecture, with a wide input voltage range of 2.7V-6.5V, suitable for a variety of power supply environments, including USB adapters, solar panels, etc. The chip through constant current and maintain charging two-stage intelligent management, with internal timer and voltage detection mechanism to ensure that the battery is fully charged and effectively extend its service life. Its eSOP-8 package is small in size and has good heat dissipation, which is very suitable for portable devices with limited space.
2. Key Features and Benefits
· Wide input voltage range: 2.7V-6.5V, adapt to a variety of power input.
· Efficient PWM control: Switching frequency up to 500kHz, support small size inductor and capacitor.
· Intelligent charging management: With constant current charging, maintain charging, automatic recharging function.
· Dual state indication output: CHRG and DONE pins indicate the charging and charging completion status respectively.
Adjustable charging current: Select two-level inductor peak current (0.62A/1.19A) through the Isel pin.
• Comprehensive protection mechanisms: Including battery over-voltage protection, chip over-temperature protection, improve system reliability.
· Input power adaptive: It can automatically adjust the charging current according to the load capacity of the power supply and support solar power supply.
3. Pin Function Description
| Pin | Name | Function Description |
|---|---|---|
| 1 | CHRG | Charging status indication (open drain), charging is low. |
| 2 | Isel | Inductor current peak selection, high level corresponds to 1.19A, low level corresponds to 0.62A. |
| 3 | BAT | Battery positive connection for voltage sampling and charging feedback. |
| 4 | GND | Systemically. |
| 5 | SW | The switch node is connected to an external inductor. |
| 6 | Wine | Input power positive. |
| 7 | DONE | End of charge indication (open drain), full low. |
| 8 | CT | The timing capacitor access terminal is used to set the maintenance charging time. |
4. working principle and charging process
The CXLB73313 uses a fixed off-time PWM buck architecture, and the charging process is divided into three stages:
4.1. Constant current charging stage
After power-on, if the battery voltage is lower than 1.36V, the chip enters the constant current charging mode. PWM controls the inductor current to be cyclically charged and discharged within the set peak value, and the CHRG pin outputs a low level.
4.2. Maintain charge phase
When the battery voltage rises to 1.36V, the chip switches to maintain charging mode, the inductor peak current decreases, and the internal timer starts. The timing time is determined by the external capacitor of the CT pin:
4.3. End of charge and recharge
When the timing ends or the battery voltage reaches 1.46V, the charging process ends and the DONE pin outputs a low level. If the battery voltage drops below 1.339V, the charging cycle is automatically restarted.
5. key parameters and design points
5.1. Inductance selection
To maintain continuous conduction mode (CCM), the following inductor values are recommended:
|
Isel Status |
Recommended inductance value |
|---|---|
|
High Level |
10µH或15µH |
|
Low level |
15µH或22µH |
The inductor saturation current shall not be less than 1.5A.
5.2. Timing Capacitor Configuration
The maintenance charging time is determined by CT pin capacitor C2. It is recommended to use 1 & micro;F or 2.2 & micro;F chip ceramic capacitor (0805/1206 package) to ensure timing accuracy.
5.3. Input and output capacitance
· Input capacitor C1: It is recommended to 4.7 & micro;F-22 & micro;F low ESR ceramic capacitors to stabilize the input voltage.
· Output Capacitor Co: Recommended 10 & micro;F-22 & micro;F Low ESR ceramic capacitors to filter out output noise.
5.4. Diode Selection
It is recommended to use a Schottky diode, its low forward voltage drop helps to improve system efficiency, and the rated current should be greater than 1.5A.
6. typical application scenarios
CXLB73313 are widely used in the following areas:
· Independent Ni-MH battery charger
· Car models and remote control toys
· Portable devices with AA/AAA batteries
· Solar powered charging system
· Emergency lighting and low voltage energy storage equipment
7. PCB Design Recommendations
To ensure system stability and low noise:
· Use double-layer PCB board to enhance grounding and heat dissipation.
· The input/output capacitor, GND pin and power ground shall be shorted through wide copper.
· Inductor, diode, and SW node wiring should be short and wide to reduce EMI emissions.
8. epilogue
With its efficient PWM control, flexible current configuration and comprehensive protection functions, the CXLB73313 provides a cost-effective solution for charging a single Ni-MH battery. Whether it is a conventional adapter or a weak power input such as solar energy, the chip can work stably, which greatly expands the application scenario. For CXLB73313 samples, technical information or procurement support, welcome to visitJTM-IC official websitefor more information.
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