TI公司的bq2407x系列是高電壓1.5A鋰電池線性充電器，具有系統功率通路管理功能，工作在USB端口或AC適配器，支持充電電流高達1.5A，輸入電壓高達28V，最大輸入電流可在100-mA和500-mA選擇，主要用在智能手機，手持媒體播放器，低功耗手持設備，手持游戲機，可穿戴，家庭自動化和手持醫療設備。本文介紹了bq24078主要特性，功能框圖，主控制充電器應用電路以及評估模塊bq24078 EVM主要特性，電路圖，材料清單和PCB設計圖。

The bq2407x is a family of integrated Li-Ion batterylinear chargers with system power path managementfunctionality targeted at space-constrained portableapplications. The devices operate from either a USBport or an AC adapter and support charge currents up to 1.5 A. The input voltage range with inputovervoltage protection supports unregulated adapters. The USB input current limit accuracy andstart up sequence allow the bq2407x to meet USB-IFinrush current specifications. Additionally， the inputdynamic power management （VIN-DPM） preventssystem crashes because of incorrectly configuredUSB sources and maximizes the power availablefrom the adapter.

The bq2407x features dynamic power pathmanagement （DPPM） that powers the system whilesimultaneously and independently charging thebattery. The DPPM circuit reduces the charge currentwhen the input current limit causes the system outputto fall to the DPPM threshold; thus， supplying thesystem load at all times while monitoring the charge current separately. This feature reduces the numberof charge and discharge cycles on the battery， allowsfor proper charge termination and enables the systemto run with a defective or absent battery pack.

Additionally， the regulated system input enables instant system turn-on when plugged in even with a totallydischarged battery. The power-path management architecture also lets the battery supplement the systemcurrent requirements when the adapter cannot deliver the peak system currents， thus enabling the use of asmaller adapter.

The battery is charged in three phases： conditioning， constant current， and constant voltage. In all chargephases， an internal control loop monitors the IC junction temperature and reduces the charge current if theinternal temperature threshold is exceeded. The charger power stage and charge current sense functions arefully integrated. The charger function has high accuracy current and voltage regulation loops， charge statusdisplay， and charge termination. The input current limit and charge current are programmable using externalresistors.

bq24078主要特性：

1? Fully Compliant USB Charger

– Selectable 100-mA and 500-mA MaximumInput Current

– 100-mA Maximum Current Limit EnsuresCompliance to USB-IF Standard

– Input-Based Dynamic Power Management（VIN-DPM） for Protection Against Poor USB Sources

? 28-V Input Rating with Overvoltage Protection

? Integrated Dynamic Power Path Management（DPPM） Function Simultaneously and

Independently Powers the System and Chargesthe Battery

? Supports up to 1.5-A Charge Current with CurrentMonitoring Output （ISET）

? Programmable Input Current Limit up to 1.5 A forWall Adapters

? System Output Tracks Battery Voltage

? Battery Disconnect Function with SYSOFF Input

? Programmable Pre-Charge and Fast-ChargeSafety Timers

? Reverse Current， Short-Circuit， and ThermalProtection

? NTC Thermistor Input

? Proprietary Start-up Sequence Limits InrushCurrent

? Battery Charge Voltage， VBAT：

– bq24076 - 4.4 V （typ）

– bq24078 - 4.35 V （typ）

? Status Indication – Charging/Done， Power Good

bq24078應用：

? Smart Phones

? Portable Media Players

? Portable Navigation Devices

? Low-Power Handheld Devices

? Portable Gaming

? Headsets

? Wearables

? Home Automation

? Portable Medical

圖1.bq24078功能框圖

圖2.bq24078/76應用電路：主控制充電器

評估模塊bq24078 EVM

This user’s guide describes the bq24076 and bq24078 （hereafter， bq24076/8） evaluation module （EVM）。

The EVM provides a convenient method for evaluating the performance of a charge management andsystem power solution for portable applications using the bq24076/8 product families. A completelydesigned and tested module is presented. The charger is designed to deliver up to 1.5 A of continuouscurrent to the system or charger for one-cell Li-ion or Li-polymer applications （see the data sheet forcorrect device） using a DC power supply. The charger is programmed from the factory to deliver 0.9 A ofcharging current. This EVM was designed as a stand-alone evaluation module， but it also can beinterfaced with the system and host via the connectors and headers.

The bq24078 evaluation module （EVM） provides a convenient method for evaluating the performance of a charge management and system power solution for portable applications using the bq24076/8 product. The charger is designed to deliver up to 1.5 A of continuous current to the system or charger for one-cell Li-ion or Li-polymer applications using a dc power supply.

評估模塊bq24078 EVM主要特性：

bq24078 is a 1.5A USB-friendly li-ion battery charger and power-path management IC

28V input rating with overvoltage protection

Input-based dynamic power management （VIN-DPN） for protection against poor USB sources

圖3.評估模塊bq24078 EVM-015外形圖

圖4.評估模塊bq24076/8 EVM電路圖

評估模塊bq24076/8 EVM材料清單：

圖5.評估模塊bq24076/8 EVM PCB頂層裝配圖

圖6.評估模塊bq24076/8 EVM PCB頂層腐蝕層

圖7.評估模塊bq24076/8 EVM PCB底層腐蝕層

詳情請見：

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