CXLB73315 is a 5V input, PWM buck architecture Ni-MH battery charging management chip, using SOP8 package, less peripheral components, strong compatibility, simple to use. The chip supports a maximum charging current of 1A, which can be flexibly set by the user through an external resistor. It has a variety of built-in satiety mechanism (including negative pressure detection, zero pressure detection, maximum voltage detection, etc.), which can be adapted to most Ni-MH batteries on the market, and has perfect protection functions, such as battery reverse connection protection, overvoltage protection and short circuit protection.
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[ CXLB73315 ]"
CXLB73315 Multi-section Ni-MH Battery Intelligent Charging Management IC Comprehensive Analysis and Application Guide
With the rapid development of portable medical equipment, power tools, small household appliances and bright flashlights, efficient, safe and intelligent battery charging management scheme has become an indispensable part of product design. As a PWM buck charge management integrated circuit designed for 1 to 3 Ni-MH batteries, CXLB73315 is becoming the first choice for many engineers because of its high integration, simple peripheral and perfect functions. This article will systematically introduce the technical characteristics, working principle, design points and typical applications of the CXLB73315 to help engineers build a high-performance and high-reliability charging system.
1. CXLB73315 Product overview
CXLB73315 is a 5V input, PWM buck architecture Ni-MH battery charging management chip, using SOP8 package, less peripheral components, strong compatibility, simple to use. The chip supports a maximum charging current of 1A, which can be flexibly set by the user through an external resistor. It has a variety of built-in satiety mechanism (including negative pressure detection, zero pressure detection, maximum voltage detection, etc.), which can be adapted to most Ni-MH batteries on the market, and has perfect protection functions, such as battery reverse connection protection, overvoltage protection and short circuit protection.
2. Key Features and Benefits
· Wide input voltage range: 4.5V-5.5V, suitable for standard 5V power supply.
· PWM Buck Architecture: Switching frequency up to 100kHz, high conversion efficiency.
· Multiple sentence satiety mechanism: Support negative pressure, zero pressure, maximum voltage judgment, applicable to a wide range of battery types.
· Intelligent charging management: It has the functions of maximum charging time limit, automatic power supply, plug-in identification, etc.
· Improve the protection mechanism: Support battery reverse connection, short circuit, overvoltage protection, high system reliability.
· Dual state indication output: CHRG and DONE pins indicate the charging and charging completion status respectively.
· Small size packageSOP8 package, suitable for application scenarios with compact space.
3. pin function details
| Pin | Name | Function Description |
|---|---|---|
| 1 | Wine | Input power positive pole, external filter capacitor. |
| 2 | FB | The battery voltage feedback terminal is used to set the output voltage. |
| 3 | CS | Charging current feedback terminal, external current detection resistor. |
| 4 | EN | The input MOS tube enables the control terminal. |
| 5 | DRV | Buck switch MOS tube drive output. |
| 6 | CHRG | Charging status indication, output high level during charging. |
| 7 | DONE | Charging completion indication, output high level after full charge. |
| 8 | GND | Systemically. |
4. working principle and charging process
The CXLB73315 adopts PWM step-down architecture, and sets the charging current and output voltage through external resistors to realize intelligent charging management of 1-3 Ni-MH batteries:
4.1. Charging current setting：
The constant current charging current is determined by the CS pin external detection resistor RCS:
4.2. Output voltage setting：
Set the FB pin voltage through the R1 and R2 divider resistors to set the battery full voltage:
The recommended configuration is as follows:
|
Number of batteries |
R1 |
R2 |
|---|---|---|
|
1 |
1kΩ |
100kΩ |
|
2 |
100kΩ |
100kΩ |
|
3 |
200kΩ |
100kΩ |
4.3. Full sentence and protection mechanisms.：
The chip supports negative pressure detection (6-10mV), zero pressure holding (60 minutes) and maximum voltage protection (1.60-1.65V per section) to ensure safe and full battery charging.
5. Status Indication Description
The CXLB73315 drives the LED indicator through the CHRG and DONE pins, and the status is as follows:
| Status | CHRG | DONE |
|---|---|---|
| Battery to be inserted | 1s flashing | 1s flashing |
| Charging | often high | often low |
| Charging complete | often low | often high |
| Abnormal alarm | 0.25s flashing | 0.25s flashing |
6. Typical Application Circuits and BOM Recommendations
The following is an example of a typical BOM representation for a 3-cell application:
| Category | Position number | Parameters | Description |
|---|---|---|---|
| Resistance | R7 | 0.1Ω 1206 | Current detection resistance |
| Resistance | R1,R2 | 100kΩ 0603 | FB voltage dividing resistor |
| Capacitance | C1-C4 | 22 μF/10V 0805 | Input/Output Filtering |
| Inductance | L3 | 10μH CD54 | power inductance |
| MOS | Q1,Q2 | 3401 SOT23 | P-MOS switch tube |
| Diode | D1 | SS14 SMA | Schottky diode |
| Master Control | U1 | CXLB73315 SOP8 | Main control IC |
7. Design Considerations
7.1. Layout recommendations：
· Current sense resistor R7 should be in close proximity to the CS and GND pins.
· Inductor and switching node (DRV) traces should be short and thick to reduce EMI and switching losses.
· The FB voltage divider network should be close to the chip to avoid noise interference.
7.2. Thermal design：
· The bottom of the chip can be properly paved with copper and punched to enhance heat dissipation.
7.3. Protection function verification：
· In practical applications, abnormal conditions such as reverse connection and short circuit should be tested to ensure that the protection mechanism is effective.
8. typical application scenarios
The CXLB73315 is suitable for a variety of scenarios that require efficient and safe charging, including:
· Portable medical equipment (e. g. electronic sphygmomanometers, hand-held monitors)
· Electric tools (e. g. hand drill, angle grinder)
· Small household appliances (e. g. sweeper, hand-held vacuum cleaner)
· Ni-MH battery charger (including seat charger, portable charger)
· Strong flashlight and emergency lighting equipment
9. epilogue
With its efficient PWM buck architecture, flexible battery configuration, multiple satiety judgment mechanism and comprehensive protection functions, the CXLB73315 is an ideal choice for charging management of 1-3 Ni-MH batteries. Whether it is a medical device, power tool or household appliance, the chip can provide a safe, efficient and reliable charging solution. For CXLB73315 samples, technical information or design support, please visitJTM-IC official websiteOr contact our technical support team.
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