CXLB73276 is a synchronous switching step-down charging management IC with input withstand voltage up to 12V and 2A output current. It adopts a highly integrated design with built-in power MOSFETs and few peripheral components, significantly reducing PCB area and system cost.
The chip adopts a fixed switching frequency of 750kHz. Under the condition of 5V input and 3.7V battery voltage, the conversion efficiency is as high as 93%, the calorific value is low, and the system stability is strong. Supports various battery specifications such as 4.2V/4.3V/4.35V/4.4V, and integrates NTC temperature protection and configurable LED status indication to meet diversified application requirements. The encapsulation form is esop8.
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[ CXLB73276 ]"
CXLB73276 efficient 2A synchronous step-down charging IC | 5V input, 93% efficiency, support NTC protection
With the rapid development of various portable electronic devices, efficient, integrated and safe lithium battery charging management scheme has become the core of product design. CXLB73276 is a synchronous switch Buck charging management chip optimized for 5V input environment, integrated with power MOS, with high withstand voltage, high efficiency, multiple protection and other characteristics, and is widely used in single lithium battery charging scenarios. This article will comprehensively analyze the technical highlights, working principles and typical applications of CXLB73276 to help engineers build a more compact, safe and efficient charging system.
I. Product Overview
CXLB73276 is a synchronous switching step-down charging management IC with input withstand voltage up to 12V and 2A output current. It adopts a highly integrated design with built-in power MOSFETs and few peripheral components, significantly reducing PCB area and system cost.
The chip adopts a fixed switching frequency of 750kHz. Under the condition of 5V input and 3.7V battery voltage, the conversion efficiency is as high as 93%, the calorific value is low, and the system stability is strong. Supports various battery specifications such as 4.2V/4.3V/4.35V/4.4V, and integrates NTC temperature protection and configurable LED status indication to meet diversified application requirements. The encapsulation form is esop8.
Second, core features
·Synchronous switch Buck architecture, efficiency up to 93%
·The charging current of the battery can reach 2A
·Input automatic throttling, adapter adaptive
·Support 4.2V/4.3V/4.35V/4.4V battery voltage customization
·Built-in NTC temperature protection function
·Configurable single light/Double Light LED charging status indication
·Input overvoltage, undervoltage, overcharge, timeout, and overtemperature protection
·ESD immunity 4KV,VIN transient withstand voltage 18V
Third, pin function and design points
3.1. Pin definition:
·VIN:5V charging input pin
·NTC: battery temperature detection pin
·LED1/LED2: charging status indicator driver
·BAT: battery positive terminal
·SW: switch node, connecting inductance
·VSYS: system power node, external capacitor required
·EPAD: heat dissipation pad, which must be connected to GND
3.2. Key design suggestions:
·The VSYS pin must be closely attached to the chip to arrange 22F ceramic capacitors, and cannot be omitted or replaced with electrolytic capacitor.
·If the NTC pin is not used, it should be grounded through 51 Kohm resistor and cannot be suspended.
·If LED1 is connected to MCU, it needs to be connected in series with 1 kOhm pull-down resistor.
IV. Workflow and protection mechanism
4.1. Charging process:
CXLB73276 complete CC/CV charging process:
4.1.1Discharge charging: when the battery voltage is less than 3V, it is precharged with 250mA low current.
4.1.2Constant current charging: After the voltage is greater than 3V, fast charging with set current (such as 2A)
4.1.3Constant voltage charging: When the voltage is close to the set value (for example, 4.2V), it is converted to constant voltage mode.
4.1.4Charging cut-off: current <400mA and stop charging after 16 seconds
4.1.5Automatic recharge: restart charging when the battery voltage is less than 4.1V
4.2. Comprehensive protection functions:
·Input undervoltage protection (4.4V) and overvoltage protection (5.6V)
·Input adaptive loop to prevent adapter overload
·NTC temperature protection: stop charging outside 0℃ ~ 45℃
·Charging timeout protection: 24 hours forced deadline
·IC over-temperature protection: 135 ℃ stop charging, 85 ℃ recovery
V. Typical application scenarios
CXLB73276 is applicable to charge management of single lithium battery of various portable devices, including but not limited:
·Mobile power supply, power bank
·Bluetooth headset, portable speaker
·Smart watch, bracelet
·Handheld medical equipment
·Electric toys, unmanned aerial vehicles
·Various IoT terminal devices
Its high integration and complete protection mechanism make it an ideal choice for applications with limited space and high requirements for safety and efficiency.
VI. Packaging and heat dissipation design
CXLB73276 is packaged in ESOP8 with a heat dissipation pad (EPAD) at the bottom. To ensure the stable operation of the chip under high load, we recommend that you:
·Copper is fully laid in EPAD area and connected to system GND
·Use multiple vias to conduct heat to the copper layer on the back of PCB
·Avoid arranging other heat sources around the chip
VII. Schematic diagram of typical applications
Eight. Summary
With its high integration, high efficiency and comprehensive safety protection function, CXLB73276 has become the preferred solution for charging management of single lithium battery in 5V input environment. Its synchronous buck architecture and intelligent charging management mechanism take into account performance, cost and reliability, which is very suitable for modern portable devices to meet the high standard requirements of power system.
If you need to obtain CXLB73276 samples, technical materials or apply for design support, please visitJTM-IC official websiteLearn more.
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