The part you need with low side switching is a device with 2 low side references.ġ. The TCA9800 is a level translating I2C Buffer, it shares the same GND between the 2 sides which can have different power supply voltage. That will keep communication flow all the time and current consumption is really low uA idle time of the bus communication? My question is do you have this kind of experience at you side?ĭo you have may be an alternative solution or improvement to the circuit. Of All three circuits it’s looks that the first setup is the way to go because power consumption is low (uA for the SMB communication) but fully charge there is no communication. The draw back of this approach is that it draws more current let say 2mA. Then both worlds are separated and will work in all situations. It looks the path will go into the BQ78350 and it blow up the SMB bus of the device communication is not possible any more.ģ: the last drawing is with galvanic isolation. Now coms the tricky part When the DSG-FET is switched of the load is cut from the B- but it will try to find a path trough the TCA 9800 and it will do. Communication is possible also when fully charged. All device are not damaged in this setup only communication fully charged is not possible.Ģ: Same circuit only the TCA is not connected to the B- but it is connected at GND side. When the capacity of the battery drops the CHG FET becomes active again and communication is reestablished again.
in this case the Hi low levels are not the same any more.
When the battery is fully charged the CHG FET is switched of communication is not possible because the GND level is 0.6V higher due to the internal Diode of the CHG-FET. When DSG is not a active the is no communication This is no problem because the U controller have no power.
In this case communication is possible as long as the DSG FET is active and CHG-FET is active.
BI FORUMS IDLE TIMER PDF
in the PDF file you see three drawings.ġ: The bq78350 is communicating trough a level shift IC TCA9800 connected at B. I have an question regarding interfacing with a BQ78350 Battery management chip BQ78350.
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