Dear Teams,
I have a customer who is asking some questions about BQ25883. Please kindly find in the following context:
Schematic Diagram showing here:
Phenomenon 1:
If we plugged in the charger and disable the MOSFET Q10, the overall system should be power off. However, BQ25883 will run its default firmware and automatically complete the charging cycle, More importantly, the charging current keeps at 240mA continuously, which is abnormal phenomenon.
Note: Vsys_S voltage always keeps at 8.6V when plug in the charging cable and MOSFET disabled. (No matter how much of voltage of battery it is)
Following picture is the Sys and SW node waveform when charging current equal to 240mA. (Blue one is SW, yellow on is Vsys)
Phenomenon 2:
Then, customer tries to pull down the power_key a little bit. Then, the Vsys_S will connect to the Vsys first and disconnect immediately (The system still not power on). At that time, the charging current goes to 1.42A.
Following picture is the Sys and SW node waveform when charging current equal to 1.42A. (Blue one is SW, yellow on is Vsys)
Question:
1. Why there is an abnormal charging current 260mA for phenomenon 1?
2. Why the charging current can go up to 1.42A for phenomenon 2?
Note:
1. Vsys_S is the system output of BQ25883. Vsys is the system overall power supply.
2. power_key is the external control side of MOSFET. When it pull down, the MOSFET enable, and Vsys_S will connect to Vsys, causing the power on of the system.
3. Customer's previous project working properly for the charging with Vsys_S connect to Vsys directly.
Thanks!
Dylan
