BQ25792: VBUS input needed to "jump-start" VSYS output?

oneil

Part Number: BQ25792

Hi TI,

I am noticing that the BQ24792's VSYS output is not enabled until power is first applied to the VBUS pins, even when a charged battery is already connected to the VBAT pin. It seems like I need to "jump-start" the BQ25792 with a power source other than the battery to get it to start working.

I am wondering if there is any way to configure the BQ25792 such that VSYS is output as soon as a charged battery is connected across VBAT and GND.

Thanks in advance for any feedback

over 1 year ago

0 Jeff F over 1 year ago

TI__Guru**** 166916 points

Hi Oneil,

V(SYS) comes up when a battery above 2.71 V max is attached if there is no shipFET and 3.55V if there is a shipFET attached.

Regards,

Jeff

0 oneil over 1 year ago in reply to Jeff F

Prodigy 115 points

Hi Jeff,

Thanks for the reply. I think there is something wrong with my implementation because I have tested with batteries exceeding both the ship mode and normal mode limits.

0 Jeff F over 1 year ago in reply to oneil

TI__Guru**** 166916 points

Hi Oneil,

There a FET with body diode from BAT to SYS. So any voltage on BAT should been seen a diode drop less on SYS.

Regards,

Jeff

0 oneil over 1 year ago in reply to Jeff F

Prodigy 115 points

Hi Jeff,

Good to know. I have determined that something about my implementation is tripping the discharge protection on my battery protection circuit, and that something happens when I connect power to the USB port that releases this protection. I am guessing the issue lies there, unless you have any other recommendation. I will mark as resolved for the time being.

Thanks

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BQ25792: VBUS input needed to "jump-start" VSYS output?