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BQ24195: Vbus is passing trough the SYS

Tulio Pires Oliveira
Prodigy 40 points
Part Number: BQ24195

Hello, I recently did the following design:

Where I have a voltage divider to keep CE at above 1.4v even for VBus as low as 7V.

Seems correct, to allow the system to disable charging mode at powe up.
However when I just power the system without the battery through VBUS I see the same output at SYS. It means if Vbus = 7V  the pin Sys= 7V. It´s quite weird i thought the system will regulate it to battery level, even without the battery.



I read in the past post that the system might work without battery: https://e2e.ti.com/support/power-management/f/196/p/701131/2586191?tisearch=e2e-sitesearch&keymatch=BQ24195

Can any one help me here, please!

  • 0
    TI__Mastermind 25800 points
    Hey Tulio,

    I would not expect VSYS to follow VBUS. That is not connect. When the input is applied, even without a battery the converter should regulated VSYS. This should like VSYS is directly connected to VBUS/PMID without switching, and that the HSFET is on indefinitely.

    Can you check the SW pin waveform to confirm that charger is switching. Even though /CE is high and disabled, this will only disable current flowing through the BATFET to charge the battery.


    Regards,
    Joel H