bq24160

您好！

在bq24160这一型号的CHARGE IC 有PMIDI和PMIDU这两个引脚，DATASHEET中说明需外接4.7UF的电容。

请问，这两引脚的作用是什么 ，为什么需要外加电容？

谢谢！

Jinrong,

   PMIDI和PMIDU是Reverse Blocking MOSFET and High Side MOSFET Connection Point，主要作用是有两种电源供电时，可选择其中一个并起防止电流反灌的作用。需要加输入电容，主要是滤除一些电源的噪声。如果只使用USB供电，IN引脚可以接地，但PMIDI需要接至少0.1uF的电容来滤波。

Dear Trevor,

另外有问题请教，在bq24160的DATASHEET中，有这样一段：

The internal battery MOSFET is used to charge the battery. When the battery is above the MINSYS votlage, the

the internal FET is on to maximize efficiency and the PWM converter regulates the charge current into the

battery. When battery is less than MINSYS, the SYS is regulated to VSYS(REG) and battery is charged using the

battery FET to regulate the charge current. There are 5 loops that influence the charge current:

? Constant current loop (CC)

? Constant voltage loop (CV)

? Thermal-regulation loop

? Minimum system-voltage loop (MINSYS)

? Input-voltage dynamic power-management loop (VIN-DPM)

During the charging process, all five loops are enabled and the one that is dominant takes control. The bq2416x

supports a precision Li-Ion or Li-Polymer charging system for single-cell applications. The Dynamic Power Path

Management (DPPM) feature regulates the system voltage to a minimum of VMINSYS, so that startup is enabled

even for a missing or deeply discharged battery. Figure 22 shows a typical charge profile including the minimum

system output voltage feature。

我不太清楚的是VSYS(REG)和MINSYS 这两个电压，为什么不将这统一为一个电压值？

另外以下这两句是否有矛盾

您好，

刚才看到，还有个问题想请教，在数据表的一段这样写到：

When a battery voltage less than VBATUVLO is connected with no input source, the battery FET is turned on similar

to supplement mode. In this mode, the current is not regulated; however, there is a short circuit current limit. If

the short circuit limit is reached, the battery FET is turned off for the deglitch time. After the deglitch time, the

battery FET is turned on to test and see if the short has been removed. If it has not, the FET turns off and the

process repeats until the short is removed. This process is to protect the internal FET from over current. If an

external FET is used for discharge, the body diode prevents the load on SYS from being disconnected from the

battery. If the battery voltage is less than VBATUVLO, the battery FET (Q6) remains off and BAT is high-impedance.

This prevents further discharging of deeply-discharged batteries.

这段中，第一句中的Less than 是不是应该为more than,不然的话，与最后一句相矛盾了。

谢谢！

有些细节不太清楚，期待您的回复！

Jinrong,

   VSYS(REG)和MINSYS的理解可以看数据手册的第2页的描述部分及图22。在电池过放或没有电池的情况下，charger是线性开通，输出一个最小的系统电压来维持系统工作。当进入正常的充电阶段时，VSYS(REG)基本是等于电池电压，如果忽略线路的阻抗。一般来说VSYS(REG)是不会低于3.5V。

Jinrong,

   是的，第一句中应该是more than, 这样电池才会给系统供电的。并且最后一句话中应该是battery FET (Q4) ，而不是Q6。数据手册有误，带来不便请谅解。

您好，Trevor:

非常感谢您的回复！

还是有点不太清楚的地方：请看数据手册Battery Charge Process部分：

When the battery is deeply discharged or shorted (VBAT < VBATSHRT), the bq2416x applies IBATSHRT to close the

pack protector switch and bring the battery voltage up to acceptable charging levels. During this time, the battery

FET is linearly regulated and the system output is regulated to VSYS(REG). Once the battery rises above VBATSHRT,

the charge current is regulated to the value set in the I2C register. The battery FET is linearly regulated to maintain the system voltage at VSYS(REG).

按照这样描述：在电池过放或没有电池的情况下，系统输出应该为VSYS(REG),而且这个值看起来应该是确定值。

还有一段：

The bq2416x monitors the charging current during the voltage-regulation phase. Once the termination threshold,

ITERM, is detected and the battery voltage is above the recharge threshold, the bq2416x terminates charge and

turns off the battery charging FET. The system output is regulated to the VSYS(REG)。

它说充电完成后，Battery charging FET关闭之后，系统输出也为VSYS(REG).

这和图22是不是不一致，图上充电后电压反而变高。

请您帮忙解释下，实在有点不太清楚数据手册的意思.

我想知道是:1.在VSYS(REG)是不是一个确定的值？

          2.在没电池或电量较低时，输出到底是VMINSYS还是VSYS(REG)?

                  3.充电完成后，输入依然在时，输出又是多少呢?

期待您的回复！

Jinrong,

   1. 在VSYS(REG)不是一个确定的值.在电池过放的情况下是3.7V，在电流充满电后是VBATREG+3%.具体可以看下数据手册的第5页

 

   2. 在没有电池或电池过放的情况下，输出是Vminsys.

    3.充电完成后，输出是寄存器里面设定Battery voltage register的值见30页 。