BQ25883: BQ25883 Charger Current Limit Register and Battery Studio setup not correct/clear

Hi Botond,

The offset is the minimum value of that register.  If you want to have 150mA charge current, you just need to select 150mA. No other math is needed.  

Regards,

Charles 

Hi Charles,

Thank you for your informaiton, but i'm a bit confused.

The same text stay at Reg00 Battery Voltage. This register is a good example:

If you check the image below, as you can see the max value is 9.2V. With all of the Register, it is possible to setup up to 2.55V. So we can not setup the 9.2V. If we want to set up the voltage we need to use the offset -> 9.2V - 6.8V = 2.4V -> This value can be set with the register.

In the document is the same text at Reg01 as you can see below. My opinion is still that either the document has a bug or the program.

Please check one more time, and give me some answer.

We have some problem with the charging current, this is the reason why a want to know this.

Best regards,

Botond

Hi Botond,

You can set the Charge Voltage to 9.2V by writing 11110000 to REG00.

Can you send me the register values of your device, so I can help debug the issue with the charge current?

Regards,

Charles

Hi Charles,

yes the 9.2V in Reg00 is clear for me. In this register you subtract the offset from the voltage value (9.2V - 6.8V = 2.4V -> 11110000). (In Reg02 you need to do the same with VINDPM to set it up right! 4.3V - 3.9V = 400mV Reg xxx00100)

It is not clear why you don't need to do the same at REG01 -> in this register was defined also an offset 100mA

Best regards,

Botond

Hi Botond,

I understand your point now. For an example of the charge current, I set 900mA in BQStudio, which using the 100mA offset should give 900mA-100mA = 800mA -> 010000 but BQStudio is giving me 010010. I will follow up on this with my team to figure this out.

In the meantime, if you could send me the value of the registers on your device, I can look into why your charge current is not as expected, and see if it is an issue unrelated to the offset.

Regards.

Charles

Hi Charles,

I am very happy to hear this.

This are the register what I am using.

And those are the value from the battery charger IC.

Charging current on the battery, is only 86.3mA

I need to know the right value of Reg01 to set it up right the charger IC.

Thank you in advance.

Best regards,

Botond

Hi Botond,

What charge current value are you trying to achieve?

Regards,

Charles

Hi Charles,

The maximum charge current from the datasheet of the battery allow 160mA, so i want to setup 150 mA.

We ordered the evolution board yesterday, with the help of the battery management studio we will be able to test this. This is how we can validate the data sent by FW.

I will keep you informe. If you have any other ideas please let me know.

Best regards,

Botond

Hi Botond,

Selecting the 150mA fast charge current in BQStudio will get you the charge current you want.  I just verified this on an EVM we have.  The binary value of the charge current in the REG01 will not incorporate the offset, but you still get 150mA. 

Regards,

Charles

Hi Charles,

thank you for the information. I will test it, but I am still waiting for the evaluation board shipment, to compare the two result. :-)

I want to go for sure now, and I want to test it thoroughly.

I will write to you if there is any new result.

Could you tell me when you release the new document, because I need to share it with the rest of the team.

Best regards,

Botond

Hi Charles,

It took a long time but I tested it. Now the charging current looks great.

Thank you for your help, and let me know if you have an update for me.

Best regards,

Botond