BQ25886: I have a few questions to ask

Zhetao,

1. ITERM can be tricky to measure correctly. Describe to me how you are accomplishing this and if possible provide a diagram of the setup.

2. I do not understand your question. COuld you please elaborate a little bit more.

3. The purpose of C9 is to store charge from REGN to drive the high side gate driver. The purpose of C14 is to stabilize the output of the REGN LDO.

Thanks,

Ricardo

Hi Ricardo！

1.I use tp5 and tp6 to measure the voltage of R6,then I know the IBAT. From the datasheet, we can know the value of iterm.

2.If I have a battery with a voltage of 8.3V, when I connect EVM, its voltage is higher than vrecharge, why does it still charge

3.Does the system judge the termination of charging only through iterm? Is it related to the battery voltage？

4.How to calculate the value of C14?

5.If I use 5V/1A adapter to charge the battery，but I set the ICHGSET=1.3A，How to realize self adaptation of the system

6.When I short-circuit vsys for a while, why does the voltage on vsys and Vbat change from 0V to 1.65V.（I'm not connected to VBUS）

Thanks for your help！

Merry Christms

Best regards from China，

Zhetao Xie

Zhetao,

1. How quickly are you sweeping the battery voltage when measuring ITERM? If you sweep too quickly the ITERM comparator will trip at 130 mA but due to the reaction time termination may occur a little bit later.

2. Could you please provide a scope capture of this please showing VBUS, IVBUS, VBAT, and IBAT?

3. The charger automatically terminates the charging cycle when the charging current is below termination threshold, charge voltage is above recharge threshold, and device is not in DPM mode or thermal regulation.

4. Due to the design of the integrated LDO and the fixed operating conditions, this is the optimal value.

5. The device will adjust the input current limit three different ways. The first is through D+/D- handshake with USB (Please short D+ and D- if you do not plan to use this feature), the second is the input current optimization algorithm, and finally the ILIM pin. Upon start up the device will choose the lowest (most restrictive) input current limit value and begin operation. If there is not enough input power available, the DPM will activate and reduce the charge current appropriately.

6. This occurs because when operating only from a battery the system is connected directly to the battery via the BATFET body diode. If you short the system to GND you short the battery to ground as well.

Thanks,

Ricardo

Hi Ricardo！

To reply question 5：I means if I set the ILIM=2A and ICHGSET=1.5A,then I use 5V/1A adapter to charge the battery.What is the IBAT value I can get？I found IBAT = 0.8A after testing.Why?How the system judges？

Merry Christmas ！

Best regards from China，

Zhetao Xie