BSI Pin in Mobile Phone

Mobile phone battery requires only two pins for charging, then why there is a third pin? The question is definitely a curiosity generating one. The third pin called BSI pin performs very important functions and act as an interface between the Mobile phone and the Battery. When the battery is removed, without switching off the Mobile phone, the BSI circuit is first interrupted which convey the information to the processor to shut down all communications to prevent damage. To communicate with the BSI, the battery pack also has a BSI pin. BSI stands for Battery Status Indicator or Battery System Indicator.

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9 thoughts on “BSI Pin in Mobile Phone

  1. I want to Switch On Nokia Mobile without using Battery. I want to use External Power Supply. Please help me how to generate BSI Voltage from External Power Supply

  2. Respective sir,
    The BSI pin is used for battery status interfacing. It is connected to a resistor to GND. 5.6 kΩ value is used for NiMH cells, 74.5 kΩis used for Li-ion ones. cells are overheating. It is a NTC thermistor (its resistance decreases with increasing temperature) connected to GND. Its value is about 40-50 kΩ at room temperature. I don’t know the exact values, it is just reference from nokia.
    One thing i noticed when BSI not connected the phone will not be power on & same thing with charging.

  3. thank you mohan sir, i think some wrong informations from the BSI pin may affect the phone’s battery indication(ie.low battery information from BSI pin of the battery even if there is more current in the battery) and it must be the reason most phones shut down even though batteries are full..

    1. Dear Ziddik

      If you are interested, you can give some articles to post in my blog with your name. Actually I am interested in building a community to share knowledge mutually in this open wireless world. If you can, type the matter in word format ( 1-2 pages) and send it as attachment. I will put some images along with it. D.Mohankumar

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