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[5:2].
2.1.1Port Power Control Using a USB Power Switch
The LAN9514 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.
5V | 5V |
PRTCTL4 | PRTCTL3 |
OCS | OCS |
USB Power | USB Power |
Switch | Switch |
EN | EN |
| | | | | | | | | | | | | | | | | | | | |
| USB | | LAN9514 | USB | |
| Device | | Device | |
| | | | | | | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | |
5V | 5V |
PRTCTL5 | PRTCTL2 |
OCS | OCS |
USB Power | USB Power |
Switch | Switch |
EN | EN |
Figure 2.2 Port Power Control with USB Power Switch
Revision 1.0 (04-20-09) | 16 | SMSC LAN9514 |
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