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Hi,
We use the BQ25730 for battery charge and BQ34Z100-R2 for gas gauge,
Now, we have below issue for the reference design:
1. We use the 18650 lithium battery, we refer to the BQ25730EVM and BQ34Z100EVM, we have no idea how to connect the BAT- and PACK-, the BQ25730 has no PACK- pin;
2. Can we fixed the CELL_BATPRESZ if we have the same series connection of battery, thanks?
Hi Zhang,
1. BQ25730 EVM charges battery with +ve terminal of battery connected to VBAT and -ve terminal of the battery connected to PGND. It is not clear from the diagram what are the functions of BAT+, BAT- and PACK-. My assumption is that PACK- is the pin from battery monitoring circuit internal to the battery pack. However, in this case I would also expect there to be a PACK+ pin which does not seem to be there. If there were a PACK+ pin, then you could connect the PACK+ to VBAT and PACK- to PGND. We need more information of the functions of the pins. Please refer to the datasheet of the battery to see if BAT- and PACK- can be shorted.
2. Can you clarify what your question is on CELL_BATPRESZ?
Best Regards,
Munir
Hi, Md,
These pictures are screenshot from the EVM( BQ25730EVM and BQ34Z100EVM), we wants to know how to design the BQ25730 and BQ34Z100-R2 output,
and we have no idea the relevance among the BAT+/ BAT-/ PACK-, the battery only 4 series and we only have the BAT+ and BAT- line.
The CELL_BATPRESZ is the selection pin for 1- to 5- cell battery setting, so if we can only 4 series that we can design same as below(only reserve the R42 and remove the R24/ R41/ R20/ R21 and JP3, is it right?
HI Zhang,
I thought the screenshot is from the battery datasheet. So please ignore the comment I made earlier. You need to connect battery +ve and -ve terminals to BAT+ and BAT- respectively. Then you will connect VBAT (from EVM) to BAT+ and PGND (from EVM) to PACK-. However, our recommendation is to use a battery protector IC on the path from VBAT to BAT+ because our charger assumes that there is a battery protector IC on the battery pack. So, with the battery protection IC it will look like this.
For CELL_BATPRESZ, yes you need to keep R42 for 4S design.
Hi Md,
This for your professional comment for this issue, but we have only the BAT+ and BAT-, so how to connect the pack-, and I have no idea what is the pack-,
so please check if we can connect the PACK- and BAT- together, thanks.
Hi Zhang,
I already described where to connect PACK- with a diagram in the previous reply. Let me know if that diagram is not visible to you. And NO, you cannot connect PACK- and BAT- together.
The bq34z100EVM user guide also describes how to connect PACK- in section 2.3.
Best Regards,
Munir
Hi Md,
Can you kindly review our schematic diagram and please check if the BAT+/ BAT-/ PACK- is right or not, thanks.
Hi Zhang,
Here is the schematic that shows how the battery connects to gauge and charger. It is recommended to add battery protection FETs in order to protect the bare cells.
I can only review the charger part of the schematic which looks ok . For the gauge schematic you need to have it reviewed by the BQ34Z100-R2 support team because you may need to separate the grounds for the gauge and the charger.
Best Regards,
Munir
Hi MD,
Pleaes advise how to identify the power on( Adapter insertion) signal from BQ25730, thanks.
Hi Zhang,
You can identify a valid adapter insertion by reading the register 21h 7th bit.
Best Regards,
Munir