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BQ77905: Bypassing Load removal method for current recovery in bq7790503

MI
Intellectual 560 points
Part Number: BQ77905

I have a EV application & using bq7790503 in it for over/under voltage, over/short current & over/under temperature protections. Most of its parameters suits my application but in current fault recovery method datasheet specifies "Load Removal + Delay".

But in my application I need only "Delay" method. Can I somehow bypass the "Load Removal" in it.

  • 0
    TI__Expert 4640 points
    HI Deepak,

    You should be able to ground the RDL resistor and this way that won't create problems with load removal. The one caveat is that that means you will have immediate current recovery when the fault condition is removed.

    Thanks
  • 0 in reply to Miguel Angel Rios
    Intellectual 560 points

    Hi Miguel,

    You mean something like this. 

    1.Also how about recovery from UV/OV./OT/UT. They are all hystersis based in bq7790503 right.

    2. In current fault recovery, now system will try to recover after 1 sec each. Right.

    Please confirm above two points?

  • 0 in reply to MI
    Intellectual 560 points
    Move up........
  • 0 in reply to MI
    TI__Mastermind 19580 points

    Hi Deepak,

    1. Yes they are. Especially by grounding the LD pin, any recovery condition that will requires "load removal" will have been met automatically and only the delay or hysteresis needs to be met.
    The down side is that if you wanted only "delay" for recovery on OCD but "load removal + hysteresis" on UV, this is not possible. On the bq7790503, I believe the UV recovery is "load removal + hysteresis" . If LD is grounded this will just be a hysteresis based recovery as the load removal has been met.
    The LD pin can also be tied directly to ground, so there is no need for a diode. A resister doesn't hurt.

    2. Yes

    Best Regards,

    -MZ

  • 0 in reply to Marcoo Z
    Intellectual 560 points
    Hi MZ,

    Thanks for response.
    I need to buy bq7790502,03,04 to check them.
    But on all major distributors: Digikey, Element14 & Mouser , only 03 is available, where I can buy 02 & 04
  • 0 in reply to MI
    Intellectual 560 points
    also,

    I am using 4 bq77905 in stackable configuration.
    what resistor divider network do u suggest for simulating cells.
    Is it 200ohms/cell?
  • 0 in reply to MI
    TI__Guru 54715 points
    Hi Deepak,
    200 ohm 1/4W resistors usually work OK unless balancing. If running balancing you may prefer a much smaller resistor of course with higher power rating.