BQ769142: 5 cells - confused about how to interconnect them

Olivier Nguyen

Prodigy 60 points

Part Number: BQ769142
Other Parts Discussed in Thread: BQ76942

Hi TI forum,

I am designing a BMS and will be using a BQ769142 as the BQ76942 or 52 are currently out of stock everywhere.

The BQ769142 is designed to be used up to 14 cells, but I will only have 5.

I'm a bit confused how I should connect them, could you please help?

I understand that cell 1 should be connected between VC0 and VC1 and that cell 5 should be connected to VC14, but I don't know how I should connect the other cells, and whether I should leave VCx unconnected or short them to another inputs.

Do you have any recommendation?

Regards,

over 4 years ago

+1 WM5295 over 4 years ago

TI__Guru 54715 points

Hi Olivier,

VCn pins are inputs and should not be left open. You are correct, cell 1 should connect at the bottom and cell 5 at the top. The middle cells can be used as desired, often it is easiest to use cells 1, 2, 3, 4 and 16 connecting VC4 through VC13A & VC13B together. See the VCn section in the BQ769142 data sheet https://www.ti.com/document-viewer/BQ769142/datasheet/GUID-AD6CC901-CE4A-46CA-93A6-0D671DAC5A31#TITLE-SLUSE91T5997987-3

You could also connect interconnects as shown in https://www.ti.com/document-viewer/BQ769142/datasheet/GUID-EC99C34B-9E07-40EE-BE21-8EFB4707FCB9#TITLE-SLUSE91T5345357-17 if desired, or connect the unused pins in pairs or multiples across the bottom 4 cells.

0 Olivier Nguyen over 4 years ago in reply to WM5295

Prodigy 60 points

Thank you for your quick answer.

I have another question: in the datasheet it is written: "Even if the host plans to control the FETs manually, the device may still change FET states based on the device settings, such as if body diode protection is enabled"

Do I understand it right by saying that the device would turn on DFET in case CFET is on and a charging current is detected, even if DFETOFF is asserted?

+1 WM5295 over 4 years ago in reply to Olivier Nguyen

TI__Guru 54715 points

Hi Olivier,

Yes, body diode protection will turn on DSG if CHG is on and charge current is detected. But if the fault is not cleared when current stops the DSG goes off again. See a description in the BQ769142 technical reference manual section 5.2.3.1 FET Configuration, it has links to related settings.

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BQ769142: 5 cells - confused about how to interconnect them