BQ78350 Charging Capabilities?

Andrew Butler

Other Parts Discussed in Thread: BQ78350, BQ40Z60, BQ27320, BQ40Z50, EV2400, BQ24190, BQ27531-G1, BQ27741-G1, BQ27200, BQ34Z100

After skimming through the datasheet for the BQ78350 fuel gauge it mentions that it supports battery charging. I am trying to figure out if I need to add an addition IC like the BQ2461x series in order to charge my Li Ions. Furthermore, if an addition charging IC is required with the BQ78350 fuel gauge, I was wondering if TI offers a solution that has charging, fuel gauge, and battery protection capacities in one IC? If not, is there any hardware reference examples that shows the use of charger, fuel gauge and battery protection ICs on one board? Lastly, I noticed that all the hardware application examples shows series configurations only. Can theses charger, fuel gauge and protection ICs be used with batteries in parallel?

over 10 years ago

0 Doug Williams4811 over 10 years ago

TI__Expert 6470 points

Hi Andrew,

The bq78350 will recommend charging voltage and charging current for various conditions. There are some chargers which can accept the charger broadcasts from the bq78350 (and other gauges) directly. More commonly, a host controller will read the recommended levels from the gauge and then send the recommendation to the charger. For specific questions about TI chargers, I would start a new message which only asks those questions and doesn't confusing things by referring to gauges.

There is one TI gauge that includes a charger, the bq40z60. It is designed for 2, 3, and 4 series cells. A reference design is available. Please check out the available documentation.

Yes, you can always add cells in parallel without any problem.

Regards,

Doug

0 Andrew Butler over 10 years ago in reply to Doug Williams4811

Expert 2520 points

So just yo further understand these ICs, you say the bq40z60 can have 2, 3, 4 batteries in series. However, can I have more than 4 batteries in parallel with the the bq40z60 and still get accurate fuel gauge measurements?

0 ThomasCosby over 10 years ago in reply to Andrew Butler

TI__Guru 73830 points

You can place multiple cells in parallel and the gauge treats them as one cell. The combined capacity cannot exceed 29Ah or you will have to use current and capacity scaling to reduce the effective capacity.

0 Andrew Butler over 10 years ago in reply to ThomasCosby

Expert 2520 points

Ok thank you for your quick responses. With respect to your last reply about batteries in parallel being treated like a single cell, I will not need to put batteries in series, only in parallel. So can you recommend a solution like the bq40z60 that is for a single cell application?

0 ThomasCosby over 10 years ago in reply to Andrew Butler

TI__Guru 73830 points

We have several single cell gauges to consider depending on whether you want to use CEDV or Impedance Track gauging.

CEDV - bq27320
IT - bq27742 with integrated protector
IT - bq27454 without the integrated protector
The single cell gauges can support up to 16Ah capacity, so you will have to scale accordingly.

We also have the bq40z50, which can support 1 to 4S and it can support 29Ah of capacity.

0 Andrew Butler over 10 years ago in reply to ThomasCosby

Expert 2520 points

Does the bq27742 or the bq40z50 have battery charging capabilities?

0 ThomasCosby over 10 years ago in reply to Andrew Butler

TI__Guru 73830 points

The bq40z60 is our only gauge with an integrated charger. Some of the other chargers offer broadcast mode to send the ChargingCurrent and ChargingVoltage to control a smart charger device.

0 Andrew Butler over 10 years ago in reply to ThomasCosby

Expert 2520 points

Ok, so will the bq40z60 work with a single cell battery?

0 ThomasCosby over 10 years ago in reply to Andrew Butler

TI__Guru 73830 points

0 Andrew Butler over 10 years ago in reply to ThomasCosby

Expert 2520 points

I think the bq40z50 would be perfect for my application but would I be able to use the SMBus as I2C because I don't see any MSP430 with a SMBus?

0 ThomasCosby over 10 years ago in reply to Andrew Butler

TI__Guru 73830 points

Andreww

You can communicate to the device with am I2C host. The EV2400 uses an MSP430 controller.

Tom

0 Andrew Butler over 10 years ago in reply to ThomasCosby

Expert 2520 points

I have been doing some digging around and I have another question for you. Can I use the BQ27741-g1 instead of the BQ27531-g1 with the BQ24190?

0 Onyx Ahiakwo over 10 years ago in reply to Andrew Butler

TI__Guru* 76230 points

Andrew,

You can but do realise the bq27741 is not a BMU in the sense that it cannot communicate with the smart charger like the bq27531 can. You host will have to read data from the gauge and communicate it to the charger.

thanks

Onyx

0 Andrew Butler over 10 years ago in reply to Onyx Ahiakwo

Expert 2520 points

Thats exactly what I was trying to figure out. Thank you for telling me that. However, to piggy back off of that fact, do I even need an additional protect IC if I use bq27531 and BQ24190 with my battery pack?

0 Onyx Ahiakwo over 10 years ago in reply to Andrew Butler

TI__Guru* 76230 points

yes, you will need a protector IC like our bq29700. You may want to consider using our bq27742 which is a gauge and protector combined in one chip. It has both firmware and hardware protection functionalities.
thanks
Onyx

0 Andrew Butler over 10 years ago in reply to Onyx Ahiakwo

Expert 2520 points

So if I use the bq27742 instead of the BQ27531-g1, what commands do I need to send to the BQ24190 charger from my MCU in order for the charger to behave like same way as if it was connected to the BQ27531-g1?

0 Onyx Ahiakwo over 10 years ago in reply to Andrew Butler

TI__Guru* 76230 points

the list of all the standard commands and subcommands are contained in the technical reference manual of the gauge. You can find this document on the product folder of the bq27742.
thanks
Onyx

0 Andrew Butler over 10 years ago in reply to Onyx Ahiakwo

Expert 2520 points

I have another completely different question now. Is the BQ27200 the only fuel gauge IC with a I2C interface that can measure the battery capacity of an Alkaline or Lithium primary battery? Or there any others?

0 Onyx Ahiakwo over 10 years ago in reply to Andrew Butler

TI__Guru* 76230 points

we have had customers use the bq34z100 for primary cells. You will have to start a separate post for that so the appropriate apps engineer can address your question if you decide to use it.

thanks

Onyx

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BQ78350 Charging Capabilities?