• State TI Thinks Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 1190 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ25616: Thermistor bypassing

Scott Cox
Prodigy 30 points
Part Number: BQ25616

Hello

I am looking to bypass the thermistor circuit on the BQ25616 in that in my design there is both no way to get a thermistor in contact with the battery and also in that I will be charging using the lowest (safest) setting of the device. The documentation does not make it clear if and how to bypass this feature. Using other devices, it is commonly as simple as using a 10k resistor in place of the thermistor. Is it possible to do this? 

Thank You

  • 0
    TI__Mastermind 25800 points

    Hey Scott,

    That is exactly right. You can just use a 10k resistor in place of the network (typical is 5.2k top resistor and 30.1k bottom resistor in parallel with the thermistor). You can also use the equivalent of 30.1k in parallel with 10k, which is ~7.5k as the bottom resistor with 5.23k still as the top resistor.

    Regards,

    Joel H

  • 0 in reply to Joel Hernandez II
    Prodigy 30 points

    Thank you Joel

    So just a 10k from TS to ground.

    One more question if you can..

    Upon power up of the device, can you tell me the states of PG (power good). Does the device power up with PG high, float, or low on power application? I'm aware that the device does a series of checks before SYS output, and in particular, what are the possible states of PG before SYS activation, and after, if any.

    My aim is to use PG to either allow the system to run normally, or to signal a shutdown and lock the system supply power off in the event of an overload. A boot loop prevention if you will..If PG has various states upon device power application, I will have to design for it, whereas if PG either floats or only indicates after SYS activation, that could be desired.

    Thank you Joel

    Scott

  • 0 in reply to Scott Cox
    Prodigy 30 points

    There was some confusion because STAT is labeled that it switches to HIGH upon sleep or charge complete. I will be using both STAT and PG. I see this now in that it is because of a required external pull-up resistor, rather than something internal to the device. The functional diagram makes the operation more clear in that it's a simple MOSFET with no other internal pull. I would like to know however, when the PG indication becomes active, or LOW, if this is before or after the device begins to output to SYS. Thank you

    Also, in reference to the first inquiry, my confusion began with the following line..

    "When TS pin is not used, connect a 10-kΩ resistor from REGN to TS and a 10-kΩ resistor from TS to GND or set TS_IGNORE to HIGH to ignore TS pin."

    Searching the datasheet, I find only one instance of "TS_IGNORE ", and seems to be more of a comment for your internal uses. 

    Is there no user way to set "TS_IGNORE" from a user standpoint?

    Shouldn't be any issues concerning, but would be nice to eliminate every non-essential component.

    Thank you once again

  • 0 in reply to Scott Cox
    TI__Mastermind 25800 points

    Hey Scott,

    The BQ25616 is a standalone charger. That appears to be a typo taken from our I2C version of this device. On this version of the device, there are no accessible registers to disable/ignore the TS function.

    And to your first question, the /PG pin pulls low before VSYS comes up to regulation (assuming you have no battery present). With a battery present that is >2.5V, the BATFET is enabled, and VSYS is up. Ideally, we suggest customers pull /PG up to the REGN rail since this rail will be active before VSYS. 

    Regards,

    Joel H