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BQ25883EVM: VBUS powerup sequencing doesn't match datasheet

Olivier Courtois
Prodigy 20 points
Part Number: BQ25883EVM


Tool/software:

I have the pullup ldo supplied by SYS.
No battery connected.

POT R5 to 0.

REGN rises 790ms after a valid 5V VBUS is inserted. Nothing happens 220ms before REGN rise. "After 220ms delay complete", 220ms after what ?

INT pulses when REGN has risen, and pulses again 7ms later. Which pulse is for the completion of the Input Source Type Detection ?
INT pulses AFTER REGN has risen, doesn't match what I read in 8.3.3.3 in datasheet.

Also, tried to write 1 in FORCE_INDET reg, and INT doesn't move, no pulse. D+ doesn't move either. How would I know that the D+/D- Detection has been completed ?

The charger is a BX-050300, probably not bc 1.2 compliant.

ch1: VREGN, ch2: INT, ch4: VBUS

I tried a different charger, which is QC, not BC1.2. And this one seems to had a D/D detection event, but It looks like there's an pull-down in the way.. 
This time, I got a INT pulse after that event, which was before REGN risen.

ch1: REGN, ch2: INT, ch3: D+, ch4: D-

I understand that I don't have a bc1.2 complaint charger, but my questions are:

- how do I know the meaning of each INT pulse I see ?
- What's event triggers the 220ms delay for the REGN ?

- Am I supposed to see a INT pulse after a FORCED D/D detection ?

Thank you, 
Olivier Courtois

  • 0
    TI__Guru** 105870 points

    Hello Olivier,

    The delay from adapter insertion to REGN powering up is provided in the datasheet, section 8.3.3.3 Power Up REGN Regulator (LDO). REGN will not power up until all the conditions are met. It appears the charger is doing input detection which can take longer depending on what adapter is being connected so it should not be expected that REGN comes up within 220ms. DCP and non-standard detections will take longest to complete.

    The sources for the interrupt pulses are outlined in the datasheet, section 8.3.9.3 Interrupt to Host. You should be able to get a good idea of what status change caused the INT pulse by reading the status or flag registers.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    Thank you, I will adapt.

    I tried a 1.2BC complaint USB hub (UH700).

    I'm unable to confirm that the D/D detection has been performed.

    after insertion, I see D- rising but being abruptly discharged. Then a first INT occurs 3.12ms later.

    ch1: D+, ch2: INT, ch3: REGN, ch4: D-

    And it's 800ms later that REGN rises.

    ch1: D+, ch2: INT, ch3: REGN, ch4: D-

    I tried writing INPUT FORCE SOURCE DETECTION (WD disabled of course), and nothing happens, nothing on the D+/D-, nothing on INT.

    What I am missing ? Or do I have a damaged IC ?

    Best Regards,
    Olivier C

  • 0 in reply to Olivier Courtois
    TI__Mastermind 41435 points

    Hi Olivier,

    What are the registers doing when this happens? Please pay attention to Section 8.3.9.3 of the datasheet for what events cause interrupts. It looks like on the first image in the last post there may be an interrupt. You can check VBUS_STAT after the interrupt to see if the D+/D- detection is finished. As Wyatt said reading the flags and registers should give a clear picture of what caused the INT.

    Regards,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    Prodigy 20 points

    I tested another unit, and it all works, the detection works.
    The device was damaged.