USB3803 datasheet(75/99 Pages) MICROCHIP

75 / 99 page

 2014-2015 Microchip Technology Inc.

DS00001691B-page 75

USB3803

PRTPWR setting will assert after initial hub customer configuration (Internal default/Serial register writes). PRTPWR will

remain asserted and under the control of the battery charge logic until one of two events.

An overcurrent is detected on the corresponding OCS_N bit. In this case, PRTPWR setting will negate. The only

way to re-enable the PRTPWR bit from this state is to RESET the USB3803.

The hub enters Hub.Communication stage, connects on its upstream port and is enumerated by a USB host. In

this case control over the PRTPWR setting reverts back to the hub logic inside the USB3803 and the normal USB

behavior applies. i.e the host must enable PRTPWR.

Since the enumeration process for a hub sets the PORT_POWER feature for all downstream ports, this information can

be used to switch control over the PRTPWR register between the battery charge logic and the hub logic.

• When the Hub PORT_POWER feature is ‘1’, the hub logic controls the PRTPWR bits.

• When the Hub PORT_POWER feature is ‘0’, the battery charging logic controls the PRTPWR bits.

No matter which controller is controlling the PRTPWR register bits, an overcurrent event will always negate PRTPWR

8.2.3

BATTERY CHARGING CONFIGURATION

Configuration of ports to support battery charging is done through serial port configuration load.

starting from Bit 1, enables Battery charging for each down stream port when asserted. Bit 1 represents port 1 and so

on. Each port with battery charging enabled asserts the corresponding PRTPWR register bit.

USB3803 Datasheet(PDF) 75 Page - Microchip Technology