TI公司的BQ24040是一款應用于面積受限的便攜式鋰離子和鋰聚合物電池線(xiàn)性充電芯片，該芯片的供電部分可以來(lái)自于USB供電或AC電源適配器供電，可以使用廉價(jià)的未經(jīng)校準的電源適配器進(jìn)行供電，因具有高的輸入電壓供電范圍及輸入過(guò)壓保護。電池充電分為三個(gè)階段，條件充電階段、恒流充電階段、恒壓充電階段。在所有充電階段，內部有監測控制回路，當芯片內部溫度超過(guò)閥值時(shí)，通過(guò)減少充電電流實(shí)現對整體電路的保護。本文首先介紹芯片的簡(jiǎn)介、特性、內部框圖及應用方向，并給出相應設計方案的設計原理圖、元器件列表及PCB元件布局圖。
The BQ24040 series of devices are highly integrated Li-Ion and Li-Pol linear chargers devices targeted at spacelimited portable applications. The devices operate from either a USB port or AC adapter. The high input voltage range with input overvoltage protection supports low-cost unregulated adapters.
The BQ24040 has a single power output that charges the battery. A system load can be placed in parallel with the battery as long as the average system load does not keep the battery from charging fully during the 10 hour safety timer.
The battery is charged in three phases: conditioning, constant current and constant voltage. In all charge phases, an internal control loop monitors the IC junction temperature and reduces the charge current if an internal temperature threshold is exceeded.

BQ24040主要特性：
• CHARGING
– 1% Charge Voltage Accuracy
– 10% Charge Current Accuracy
– Pin Selectable USB 100mA and 500mA Maximum Input Current Limit
– Programmable Termination and Precharge Threshold, bq24040 and bq24045
– High voltage (4.35V) Chemistry Support with bq24045
• PROTECTION
– 30V Input Rating; with 6.6V or 7.1V Input Overvoltage Protection
– Input Voltage Dynamic Power Management
– 125°C Thermal Regulation; 150°C Thermal Shutdown Protection
– OUT Short-Circuit Protection and ISET short detection
– Operation over JEITA Range via Battery NTC – 1/2 Fast-Charge-Current at Cold, 4.06V at Hot, bq24040 and bq24045
– Fixed 10 Hour Safety Timer, bq24040 and bq24045
• SYSTEM
– Automatic Termination and Timer Disable Mode (TTDM) for Absent Battery Pack With Thermistor, bq24040 and bq24045
– Status Indication – Charging/Done
– Available in Small 2×2mm2 DFN-10 Package
– Integrated Auto Start Function for Production Line Testing, bq24041

BQ24040應用方向：
• Smart Phones
• PDAs
• MP3 Players
• Low-Power Handheld Devices

圖1. BQ24040內部方框圖

BQ24040方案介紹：
The bq2404x series of devices are highly integrated Li-ion linear charger devices targeted at space-limited portable applications. The devices operate from either a USB port or AC adapter.
The bq2404x has a single power output that charges the battery. A system load can be placed in parallel with the battery as long as the average system load does not keep the battery from charging fully during the 10 hour safety timer.
The battery is charged in three phases: conditioning, constant current, and constant voltage. In all charge phases, an internal control loop monitors the IC junction temperature and reduces the charge current if an internal temperature threshold is exceeded.
The charger power stage and charge current sense functions are fully integrated. The charger function has high-accuracy current and voltage regulation loops, charge status display, and charge termination. The pre-charge current and termination current threshold are programmed via an external resistor on the bq24040 and bq24045. The fast charge current value is also programmable via an external resistor.

BQ24040方案原理圖：

圖2. BQ24040方案原理圖

BQ24040方案材料清單：


PCB元件布局圖：