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BQ25898D: USB data lines without VBUS

Alex Münnich
Prodigy 20 points
Part Number: BQ25898D
Other Parts Discussed in Thread: TS5USBC41,

Dear TI support,

we're trying to incorporate the BQ25898D into a portable product which makes use of USB type C (DRP). Since both charger and processor need access to the USB data lines, we use the TS5USBC41 to switch between these devices. In our current design is VBUS applied delayed because the USB type C controller performs a handshake initially.

Will it pose a problem when the data lines are connected before VBUS? We assumed for now it's unsafe and therefore added two N-channel MOSFETs to control the output enable pin on the mux only when VBUS is already applied or when the system is running in host mode.

Thanks in advance for your support.

Regards,

Alex

  • 0
    TI__Guru 57391 points

    Alex,

    D+/D- pins are used for USB input current limit detection when VBUS power is plugged in. During the BQ25898D input current limit detection process, the host must be able to HIZ D+/D- pins so that D+/D- pins are driven by the BQ25898D. The BQ25898D will HIZ D+/D- pins when D+/D- pins are not needed for input current limit detection so that other devices may drive D+/D- pins.

    Thanks,

    Ning.