Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

  • State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 524 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

BQ24298: Vsys remains unregulated

JASPER SIKKEN
Prodigy 50 points
Part Number: BQ24298
Other Parts Discussed in Thread: BQ24296M

I have copied the typical application design, and followed the PCB layout guidelines, however Vsys remains unregulated. I always measure vbat voltage. I have checked my schematic symbol, footprint, checked reference design, used the recommended components, replaced the inductor, checked and changed pulls on PSEL, OTG and CE, made QON low for a while. I could not find any register bit that needs to be set to enable VSYS regulation. I think I don't need to make I2C register setting for VSYS to regulated. I think VSYS should always be slightly above battery voltage but not lower than Vbat, right? Why is VBAT not regulated? 

  • 0
    Prodigy 50 points

    Added schematic and PCB layout because copy-paste did not work

  • 0 in reply to JASPER SIKKEN
    TI__Guru 52371 points

    Hi,

    Please visit https://e2e.ti.com/support/power-management/f/196/t/878463 for BQ2429X: Schematic Review and PCB Layout Design Tips and https://e2e.ti.com/support/power-management/f/196/t/875388 for BQ2419X/2429x FAQs. BQ24298 is similar to BQ24296M.

    What are your test conditions such as VBUS (voltage at VBUS pin), IVBUS, VBAT (voltage at BAT pin), IBAT, VSYS, ISYS? Could you please provide all register values of the charger?

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 50 points

    Hi Ning T, 

    I have checked the schematic review, PCB layout tips, as well as the FAQ I believe my design is correct. Can you please confirm?

    Vbus is either connected to a 5V/2A source and Vbus is 4.85V Ibus is 1.8A or not connected. 

    PMID is 3.3V (Vbat=3.5V and VBUS=0V) or 3.78V when VBUS is connected to 5V/2A source. 

    VREGN is either 4.7V or 0V

    Vbat=3.46V, IBAT=5mA-4A, Vsys=3.46V, Isys=5mA-4A

    I do not have all register values because I have not yet implemented. Is it required? Do I need to set any register for Vsys to be regulated? What is required for Vsys to become regulated?

    Thanks, 

  • 0 in reply to JASPER SIKKEN
    Prodigy 50 points

    I checked the reference, schematic and layout tip and FAQs. Can you please confirm I am not missing something?

    Does BQ24298 work without setting any I2C register?

    What is rquired for VSYS to become regulated?

    Can you please answer?

  • 0 in reply to JASPER SIKKEN
    TI__Guru 52371 points

    Hi,

    The host is not required for normal operations. But it will be easier to debug with reading register values via I2C and check the charger status/faults.

    It looks like VSYS is ok when VBAT is present. Are you inquiring about operating with VBUS source? Please refer to 8.3.1.3 Power Up from DC Source and 8.3.1.4 Converter Power-Up for VSYS start-up. In theory, VSYS is regulated with valid VBUS voltage if there's no faults, DPM etc. The BQ2419X/2429x FAQs provided earlier gives some common causes for not having regulated VSYS.

    Please check if STAT and/or INT indicate any faults and debug from there. Please also check if the input source is over-loaded, either the current exceeds the input current limit or the VBUS pin voltage falls below the input voltage limit. Please refer to 8.3.2.2 Dynamic Power Management Dynamic Power Management on the d/s for the details.

    Thanks,

    Ning.