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TPS659xx: USB charger and constant voltage

Q: Can TPS659xx devices be powered ON with a USB charger only (no battery connected)

 A: No. This is not a valid configuration. This feature called constant voltage is supported only with AC chargers and not with USB chargers. For details you can see the battery management interface chapter in the correcponding TRM document. Documents are available at - http://focus.ti.com/docs/prod/folders/print/tps65950.html 

  • Hi,

    Is it possible to connect VBUS line both to VAC and VBUS in order to keep capability of instant on feature using only USB line?

     

    Thanks,

    David

  • Hi,

    Yes, it is possible to have this connection.

    However, there will be a limitation if the VBUS supply comes from a "true" USB device because USB standard allows only 100mA (max). If charging is done with this type of supply then the device will not power ON as the supply voltage will be pulled very low. If the VBUS is from a non-standard USB which can supply higher current then the software configuration in the device registers can be changed to increase to a required current limit.

    Details on register description can be found in the "Battery Charger Interface" chapter of the TRM.

    Regards,

    Gandhar.