CXLB73316 is a Ni-MH battery charging management chip with PPM boost architecture, which supports series charging of 4-12 batteries, with a wide input voltage range of 2.7V-6.5V, and is compatible with multiple power inputs. The chip integrates the reference voltage source, inductor current detection, battery voltage feedback, overvoltage protection and other modules, and only a few components are needed to build a complete charging system. Its SSOP10 package is small in size and has good heat dissipation, which is suitable for high-power applications with compact space.
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[ CXLB73316 ]"
CXLB73316 Multi-section Ni-MH Battery Boost Charge Management IC Depth Analysis and Application Guide
With the rapid development of applications such as power tools, independent chargers, and large-capacity energy storage devices, the demand for efficient and safe charging management of multi-section Ni-MH batteries is increasing. As a step-up charging control integrated circuit designed for 4 to 12 Ni-MH batteries, CXLB73316 is an ideal choice for charging high-string battery packs with its output power of up to 35W, wide input voltage range (2.7V-6.5V) and comprehensive protection functions. This article will comprehensively introduce the technical characteristics, working principle, design points and typical applications of the CXLB73316 to help engineers build an efficient and stable high-power charging system.
1. CXLB73316 Product overview
CXLB73316 is a Ni-MH battery charging management chip with PPM boost architecture, which supports series charging of 4-12 batteries, with a wide input voltage range of 2.7V-6.5V, and is compatible with multiple power inputs. The chip integrates the reference voltage source, inductor current detection, battery voltage feedback, overvoltage protection and other modules, and only a few components are needed to build a complete charging system. Its SSOP10 package is small in size and has good heat dissipation, which is suitable for high-power applications with compact space.
2. Key Features and Benefits
· Wide input voltage range: 2.7V-6.5V, adapt to a variety of power input.
· High output power: Support up to 35W charging power, suitable for large-capacity battery packs.
· Intelligent charging management: With constant current charging, maintain charging, automatic recharging function.
· Multiple sentence satiety mechanism: Support voltage detection and timing control to ensure that the battery is fully charged.
• Comprehensive protection mechanisms: Including battery overvoltage protection, input undervoltage lockout, chip enable control.
· Input power adaptive: The input voltage can be automatically adjusted according to the load capacity of the power supply.
· Status indication output: STAT pin supports LED or MCU interface, real-time display of charging status.
· High-frequency switch operationUp to 1MHz switching frequency, supporting small size inductors and capacitors.
3. pin function details
| Pin | Name | Function Description |
|---|---|---|
| 1 | STAT | Charging status indicator (CMOS output), high level indicates charging. |
| 2 | CE | Chip enable input, high level enables chip. |
| 3 | FB | The battery voltage feedback input is used to set the output voltage. |
| 4 | BAT | Battery positive connection end. |
| 5 | GND | Systemically. |
| 6 | LDRV | External N-MOSFET gate drive output. |
| 7 | HDRV | External P-MOSFET gate drive output (optional). |
| 8 | Wine | Input power positive. |
| 9 | CSN | Inductor current detection negative input. |
| 10 | CT | Timing capacitor access terminal, set to maintain charging time. |
4. working principle and charging process
The CXLB73316 uses a boost architecture to set charging parameters through external resistors and capacitors for intelligent charging management:
4.1. Constant current charging stage
After power-on, the chip controls the external N-MOSFET to turn on, the inductor current rises to a set upper limit (such as 0.123V/RCS) and then turns off, and the energy is transferred to the battery. The current is turned on again at the lower limit (e. g., 0.087V/RCS), forming a cycle.
4.2. Maintain charge phase
When the FB voltage reaches 1.125V (typical value), the chip switches to the maintenance charge mode, the input current drops to 66% of the constant current phase, and the internal timer is started. The timing time is determined by the CT pin capacitance:
4.3. End of charge and recharge
When the timing ends or the FB voltage reaches 1.205V, the charging process ends. If the FB voltage drops to 1.105V, automatically restart the charging cycle.
5. key design points
5.1. Current sense resistor setting
The charging current is determined by the RCS resistance value, and the average inductor current in constant current mode is:
5.2. Output voltage configuration
The battery full pressure is set by the R1 and R2 voltage dividing resistors:
5.3. Inductance and switching frequency selection
It is recommended to set the switching frequency at 300kHz-600kHz, the inductance value is generally 3.3 μH-15μH, and the saturation current must be greater than the peak current.
5.4. Peripheral component selection
· MOSFET: The N-MOS breakdown voltage needs to be higher than the maximum voltage of the battery. Low Qg devices are recommended to improve efficiency.
· Diode: It is recommended to use Schottky diodes, such as SS24/SS34, to reduce conduction losses.
· Input/output capacitance: X5R/X7R ceramic capacitor with low ESR is recommended, and the capacity is 4.7 μF-47μF according to the current.
6. typical application scenarios
The CXLB73316 is suitable for a variety of high-power, multi-cell battery charging scenarios, including:
· Power tools (e. g. drill, angle grinder)
· Independent Ni-MH battery charger
· Large capacity toy model
· Emergency power supply and energy storage equipment
· Industrial Handheld Devices
7. Design Example Reference
The following are component selection recommendations for a typical 5V input at different current levels:
| Parameters | 0.9A | 1.8A | 3.6A | 5.4A | 7.2A |
|---|---|---|---|---|---|
| RCS | 120mΩ | 60mΩ | 30mΩ | 20mΩ | 15mΩ |
| Inductance | 10μH | 6.8μH | 3.3μH | 2.2μH | 2.2μH |
| Switching frequency | 560kHz | 415kHz | 420kHz | 420kHz | 320kHz |
8. PCB Design Recommendations
8.1. Layout Points：
· The current sense resistor RCS should be close to the VIN and CSN pins.
· Input/output capacitors and power ground shall be shorted through wide copper sheet.
· Inductance and switch node traces should be short and thick to reduce EMI and loss.
8.2. Thermal design：
· Power devices (MOSFETs, diodes) should be placed in a well-ventilated area, with cooling holes if necessary.
9. epilogue
With its efficient boost architecture, flexible configuration options, comprehensive protection mechanism and high output power capability, the CXLB73316 provides a highly reliable and highly integrated solution for charging 4-12 Ni-MH batteries. Whether it is a power tool, a stand-alone charger or industrial equipment, the chip can meet the demanding charging needs. For CXLB73316 samples, technical information or design support, please visitJTM-IC official websiteOr contact our technical support team.
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