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Original question:

BQ24610: BQ24610 - Undervoltage lockout Implementation

BQ24610: BQ24610

Tee David
Prodigy 60 points
Part Number: BQ24610

Tool/software:

Hi,

I am trying to design a single cell charger circuit with a fast-charging current of 10A, pre-charge and termination current of 2A and charging voltage at 4.2V. I am not planning to monitor the cell temperature because i am not expecting it to rise above normal during charging, so I want to do away with the thermistor. My question is, how do I connect the TS pin? 

  • 0 in reply to Christian Moyer
    Prodigy 60 points

    Hello Christian,

    Thank you for your message. That really helped.

    I do have another question though. Since I am planning to achieve a fast charging current of 10A, is it advisable to use a power supply that is able to supply above 10A, probably in the range of 10 to 15A to the circuit?

    Kind Regards,

    Tee

  • 0 in reply to Tee David
    TI__Mastermind 32771 points

     Hello Tee,

     

    This will be dependent of your system load and adapter voltage. I typically recommend an adapter that can support a couple Watts higher than the maximum battery/system load.

    Best Regards,

    Christian

  • 0 in reply to Christian Moyer
    Prodigy 60 points

    Hi Christian,

    The design is only meant to charge a single cell at 4.2V and 10A fast charging current. I want to use an adapter that can supply 24V to the design, and was just wondering if I could make use of an adapter that can supply up to 10A or more. Did you mean adapter current does not matter even if my fast-charging current will be 10A?

    Regards,

    Tee

  • +1 in reply to Tee David
    TI__Mastermind 32771 points

    Hello Tee,

    Tee David said:
    and was just wondering if I could make use of an adapter that can supply up to 10A or more. Did you mean adapter current does not matter even if my fast-charging current will be 10A?

    Yes, This is correct, as long as it can support the maximum power drawn from the battery. If you are using a 24V adapter, I recommend an adapter that can support 2A or greater. So the the 10A adapter will be fine.

    4.2A*10=42W

    24*1.75=42W

  • 0 in reply to Christian Moyer
    Prodigy 60 points

    Hello Christian,

    Christian Moyer said:

    Yes, This is correct, as long as it can support the maximum power drawn from the battery. If you are using a 24V adapter, I recommend an adapter that can support 2A or greater. So the the 10A adapter will be fine.

    4.2A*10=42W

    24*1.75=42W

    I got an adapter that is able to supply the maximum power drawn from the battery (Battery will draw 42W and adapter power rating is 350W), but the current output of the adapter is 15A. Based on your previous message, this shouldn't matter since we are only concerned with the adapter power rating and also, since the adapter current is more than 2 A (even though it is 15A, this should be fine right?

    I am asking because i got a spreadsheet from your site that only set the ACSET pin to 2V if adapter current is 10A and sets the pin to higher values (I know from the data sheet that ACSET pin voltage should be between 0 - 2V), if adapter current is more than 10A. For example, for Iadp of 15A, the formula in the spreadsheet sets ACSET value to 3V (irrespective of the resistor divider values) based on the formula from the data sheet as shown below.

    Please see a screenshot from the spreadsheet below

    This spreadsheet is confusing because I know ACSET pin voltage is set by the resistor divider.

    Looking forward to hearing from you.

    Thank you,

    Tee

  • 0 in reply to Tee David
    TI__Mastermind 32771 points

    Hello Tee,

    Tee David said:
    I got an adapter that is able to supply the maximum power drawn from the battery (Battery will draw 42W and adapter power rating is 350W), but the current output of the adapter is 15A. Based on your previous message, this shouldn't matter since we are only concerned with the adapter power rating and also, since the adapter current is more than 2 A (even though it is 15A, this should be fine right?

    This is correct.

    Do you have link spreadsheet, I'm too sure which tool this is refering to.

    Best Regards,

    Christian.

  • 0 in reply to Christian Moyer
    Prodigy 60 points

    Hello Christian,

    Thanks for getting back to me. I do not have the link but I know i downloaded it from your site. I would love to share the spreadsheet with you, is there a way to attach it on here? 

    Regards,

    Tee

  • 0 in reply to Tee David
    TI__Mastermind 32771 points

    Hello Tee,

    It should be the same way that you attached the picture above.

    Best regards,

    Christian

  • 0 in reply to Christian Moyer
    Prodigy 60 points

    1200.bqstroller calculation tools_V1.5.xls

    Hello Christian,

    The spreadsheet is attached.

    Regards,

    Tee

  • 0 in reply to Tee David
    TI__Mastermind 32771 points

    Hello Tee,

    Okay, I understand now. IADP is not the maximum current that the adapter can provide. IADP is the max input current limit. It's the maximum current that you want the device to pull from adpater.

    For Example: If you have a short or some kind of failure, you can set IADP to prevent the the device from pulling too much current from the adapter.If you don't set this limit, it might pull the full 15A that the adapter can provide and damage the device.

    As you mentioned before, your battery is pulling 42W. You will want to set the device to be able to support greater than 42W. Your input voltage is 24V.

    24V*1.75A=42W.

    So I would recommend setting it up to support an input current of 2.5-3A.

    So in the calculation above you would set IADP to 2.5-3A

    Best Regards,

    Christian.

  • 0 in reply to Christian Moyer
    Prodigy 60 points

    Hello Christian,

    I am planning on charging a single li-ion cell with a fast charging current of 10A and 4.2V charging voltage. My voltage input will be 24V. I am not going to utilize the system feature because I am only designing for charging the cell only. I feel IADP should be set to 10A, since that is also my charging current and the maximum the charger IC can support. In other words, my IADP should be equal to my ICHARGE in this case. The suggested IADP calculation in your message is 2.5-3A, can IADP be lower than ICHARGE?

    Regards,

    Tee.

  • 0 in reply to Tee David
    TI__Mastermind 32771 points

    Hello Tee,

    Tee David said:
    The suggested IADP calculation in your message is 2.5-3A, can IADP be lower than ICHARGE?

    Yes, since this is a buck charger, the IADP is always going to be lower than ICHARGE. Please see calculation down below. The buck charger will step the voltage down while also increasing the current to maintain that the power in is the same as the power out. However, since this device is not 100% efficient, there will be some power loss, so you will need to increase the power in to support power out and power loss. this is why I recommend increasing the IADP current from 1.75A to 2.5A

    4.2V*10A(ICHARGE)=42W

    24V*1.75A(IADP)=42W

    24V*2.5A(suggested IADP)=60W

    Best Regards,

    Christian

  • +1 in reply to Christian Moyer
    Prodigy 60 points

    Hello Christian,

    Thank you for the detailed explanation. This is clear.

    Kind Regards,

    Tee