• State Resolved
  • Locked Locked
  • Replies 7 replies
  • Subscribers 63 subscribers
  • Views 922 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.

BQ24600 internal timer

Ran Aloni
Expert 2386 points
Other Parts Discussed in Thread: BQ24133, BQ24610

Dear All,

a question about the timer fault conditions:

on page 18 on the datasheet there is a description of the timer fault recovery.
I'm charging a battery with ~0.1C which means a ~11 hours CC/CV charge.

let me see if I got it right:

according to condition 1, when the voltage VFB pin voltage, rises over 2.05V + ~50mV  - which means entering the CV part of the charge, the chip measures 5 hours, if 5 hours has past before charge ends, a timer fault occur.

does condition 2 mean I could never reach a full charge since my CC part of the charge is well over 5 hours?

or does it relate to the battery detection algorithm, mentioned on page 20? which is active when battery is under the recharge voltage?

please clear this point to me so I can be sure I can go to production stage...

best regards,

  • 0
    Expert 2386 points

    Dear all,

    any comment?

    thanks

  • 0
    TI__Mastermind 31120 points

    this part has a fixed 5 hour timer and is typically good for a C/3 or faster charge.

    If you charge at C/10 you will get a safety timer fault.  The description on page 18 that you refered to is about clearing a safety fault that has occured.  The recovery on the safety fault is extreemly slow.  Typically the condition does not occur unless something is wrong with the battery pack or the design was not set up properly.

    The trickle current during a safety fault is mostly for if the pack is removed the trickle current will charge up the battery capacitance on the board up above the refresh threshold within a second and if a pack is reinserted and pulled below the refresh threshold a new charge will begin.  Also unplugging the adapter and replugging will start a new charge also.

    It would be best to use a part with an adjustable safety timer line the bq24133.

    How many series cells are being used?

     

  • 0 in reply to Charles Mauney
    Expert 2386 points

    Dear Charles,

    thanks for your reply,

    Really bad news for me...

    the charger is fixed inside the casing and away from the customer.

    any way to bypass this fault?

    I have 5 cells in serious so BQ24133 doesn't fit, I would need something from the BQ246** series but with the TTC pin...
    which one will cause me the least layout and schematics changes?


    regards,

  • 0 in reply to Ran Aloni
    Expert 2386 points

    Dear Charles,

    I think that BQ24610 will be suitable because of its 10 hours timer.

    but I do not want to use the powerpath or DPM option, since I always want to use the battery as the power source.

    what changes are needed to be done?

    just leave ACN, ACP, !ACDRV, ACSET, and !BATDRV open?

    regards,

  • 0 in reply to Ran Aloni
    TI__Mastermind 31120 points

    I would float the ACDRV and BATDRV, lleave a divider on the ACSET and short across the Rac resistor (shorting the ACN and ACP together).

  • 0 in reply to Charles Mauney
    Expert 2386 points

    thanks a lot,

    any suggestion on the divider values? I want to avoid increasing the standby currents.

    since there is no Rac, what will happen inside the chip?
    is setting the any voltage on ACSET (which is higher then the 0 on ACN-ACP) will keep 0v on BATDRV and ACDRV?


    regards,

  • 0 in reply to Ran Aloni
    TI__Mastermind 31120 points

    100k and 50k should work.

    With the Rac resistor shorted the input current loop will never kick in to reduce the charging current.

    The BAT and AC drives are alway out of phase and when the input voltage is greater than the battery voltage the IC is out of sleep mode and the AC FET should be on and BAT FET off and if the input voltage is lower than the battery the BAT FET is on and the AC FET off.

    Since you indicated that you would not use power path, then one would not have the AC and BAT FETS and the IC is just a charger.