USB Hub with Integrated 10/100 Ethernet Controller
Datasheet
2.1Port Power Control
This section details the usage of the port power control pins PRTCTL[3:2].
2.1.1Port Power Control Using a USB Power Switch
The LAN9512 has a single port power control and over-current sense signal for each downstream port. When disabling port power the driver will actively drive a ‘0’. To avoid unnecessary power dissipation, the internal pull-up resistor will be disabled at that time. When port power is enabled, the output driver is disabled and the pull-up resistor is enabled, creating an open drain output. If there is an over-current situation, the USB Power Switch will assert the open drain OCS signal. The schmitt trigger input will recognize this situation as a low. The open drain output does not interfere. The overcurrent sense filter handles the transient conditions, such as low voltage, while the device is powering up.
EN
USB
Device
Figure 2.2 Port Power Control with USB Power Switch
Revision 1.0 (04-20-09) | 16 | SMSC LAN9512 |
| DATASHEET | |
