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BQ24070RHLR 参数 Datasheet PDF下载

BQ24070RHLR图片预览
型号: BQ24070RHLR
PDF下载: 下载PDF文件 查看货源
内容描述: 单片锂离子充电和系统电源路径管理IC [SINGLE-CHIP LI-ION CHARGE AND SYSTEM POWER-PATH MANAGEMENT IC]
分类和应用: 电源电路电源管理电路
文件页数/大小: 26 页 / 652 K
品牌: TI [ TEXAS INSTRUMENTS ]
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bq24070  
bq24071  
www.ti.com  
SLUS694BMARCH 2006REVISED AUGUST 2006  
FUNCTIONAL DESCRIPTIONS (continued)  
Autonomous Power Source Selection, Mode Control Pin  
With the MODE input low, the bq24070/1 defaults to USB-mode charging, and the supply current is limited by  
the ISET2 pin (100 mA for ISET2 = Low, 500 mA for ISET2 = High). If an input source is not available, then the  
battery is selected as the source.  
Boot-Up Sequence  
In order to facilitate the system start-up and USB enumeration, the bq24070/1 offers a proprietary boot-up  
sequence. On the first application of power to the bq24070/1, this feature enables the 100-mA USB charge rate  
for a period of approximately 150 ms, (t(BOOT-UP)), ignoring the ISET2 and CE inputs setting. At the end of this  
period, the bq24070/1 implement CE and ISET2 input settings. Table 1 indicates when this feature is enabled.  
See Figure 8.  
Power-Path Management  
The bq24070/1 powers the system while independently charging the battery. This feature reduces the charge  
and discharge cycles on the battery, allows for proper charge termination, and allows the system to run with an  
absent or defective battery pack. This feature gives the system priority on input power, allowing the system to  
power up with a deeply discharged battery pack. This feature works as follows:  
AC Adapter  
(2)  
IN  
OUT  
VDC  
GND  
System  
Q1  
PACK+  
PACK−  
BAT  
40 mΩ  
+
Q2  
bq24070/1  
UDG−04082  
Figure 4. Power-Path Management  
Case 1: AC Mode (Mode = High)  
System Power  
In this case, the system load is powered directly from the AC adapter through the internal transistor Q1 (see  
Figure 4). The output is regulated at 4.4 V (bq24070). If the system load exceeds the capacity of the supply, the  
output voltage drops down to the battery's voltage.  
Charge Control  
When in AC mode the battery is charged through switch Q2 based on the charge rate set on the ISET1 input.  
Dynamic Power-Path Management (DPPM)  
This feature monitors the output voltage (system voltage) for input power loss due to brown outs, current limiting,  
or removal of the input supply. If the voltage on the OUT pin drops to a preset value, V(DPPM) × SF, due to a  
limited amount of input current, then the battery charging current is reduced until the output voltage stops  
dropping. The DPPM control tries to reach a steady-state condition where the system gets its needed current  
and the battery is charged with the remaining current. No active control limits the current to the system;  
therefore, if the system demands more current than the input can provide, the output voltage drops just below  
the battery voltage and Q2 turns on which supplements the input current to the system. DPPM has three main  
advantages.  
12  
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