• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 646 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.

BQ25505

Erin McCook
Prodigy 65 points
Other Parts Discussed in Thread: BQ25505

I have been testing the threshold for the VBAT_OK threshold and what I am seeing is that I have programmed for a descending voltage a threshold on VSTOR 2.336V and I am watching it trip at different voltages each time I tested it. I saw a trip voltage of 2.680V, 2.607V and then 2.404V remember my trip voltage is (2.336V). I am bleeding off the SEC_STORAGE with a 16mA resistive load and measuring the voltage with a scope.  On the VBAT_OK_HYST I had programmed value of 2.68V for the ascending voltage. I have since tested this three times and I am seeing a voltage of 2.81V, 2.691V and 2.683V my programmed value was a(2.680V). What I am trying to find out is if this is a normal expected variation in the VBAT_OK threshold and if so what would the max/min variations over temperature.  

  • 0
    TI__Guru**** 166826 points
    First, keep in mind that the VSTOR value is only sampled every 64ms so if your ramp rate is faster than that, the actual VBAT_OK trip point will be slightly different than you have configured with the resistors. Second, if you installed >1Mohm, new resistors using solder with flux, the residual flux can create parasitic, varying resistors in the 1Mohm range that are in parallel with your voltage setting resistors. If extreme cleaning with alcohol doesn't work for prototyping, try standing the resistors on their side (tombstone). For production, you would need to use a vendor with a board cleaner that can remove ionic contaminants.
  • 0 in reply to Jeff F
    TI__Prodigy 65 points

    I have an additional question related to the BQ25505 - what is recommended for ESD protection on the input through the solar cell. We do locks, and locks require a lot of esd protection as they are touched all the time.

  • 0 in reply to Erin McCook
    TI__Guru**** 166826 points
    If you need more ESD protection than the IC itself warranties per the ESD handling section of the datasheet, I would suggest adding an ESD protection device. Unfortunately, I am not familiar with those devices. TI's Interface group makes the TPD family of ESD protection diodes that might be a fit.