SMSC USB2512i - Manual (Page 8)

Industrial Temperature Rated USB 2.0 High-Speed 2-Port Hub Controller
Datasheet
Revision 1.92 (11-28-07) 8 SMSC USB2512i
DATASHEET
Chapter 3 Pin Descriptions
3.1 PIN Descriptions
This section provides a detailed description of each signal. The signals are arranged in functional
groups according to their associated interface.
The “N” symbol in the signal name indicates that the active, or asserted, state occurs when the signal
is at a low voltage level. When “N” is not present before the signal name, the signal is asserted when
at the high voltage level.
The terms assertion and negation are used exclusively. This is done to avoid confusion when working
with a mixture of “active low” and “active high” signals. The term assert, or assertion, indicates that a
signal is active, independent of whether that level is represented by a high or low voltage. The term
negate, or negation, indicates that a signal is inactive.
Table 3.1 USB2512i Pin Descriptions
SYMBOL
QFN-36
EMB
BUFFER
TYPE DESCRIPTION
UPSTREAM USB INTERFACES
USBUP_DP
USBUP_DM
31
30
IO-U USB Bus Data
These pins connect to the upstream USB bus data signals
(Host port, or upstream hub).
VBUS_DET 27 I/O12 Detect Upstream VBUS Power
Detects state of Upstream VBUS power. The SMSC Hub
monitors VBUS_DET to determine when to assert the internal
D+ pull-up resistor (signaling a connect event).
When designing a detachable hub, this pin must be connected
to the VBUS power pin of the USB port that is upstream of the
hub.
For self-powered applications with a permanently attached
host, this pin must be connected to 3.3V (typically VDD33).
DOWNSTREAM 2-PORT USB 2.0 INTERFACE
USBDN_DP[2:1]/
&
USBDN_DM[2:1]/
4
2
IO-U High-Speed USB Data
These pins connect to the downstream USB peripheral devices
attached to the hub’s port. 3
1
PRTPWR[2:1] 16
12
O12 USB Power Enable
Enables power to USB peripheral devices downstream.
Note: The hub supports active high power controllers only!
OCS[2:1]_N 17
13
IPU Over Current Sense
Input from external current monitor indicating an over-current
condition.
{Note: Contains internal pull-up to 3.3V supply}
RBIAS 35 I-R USB Transceiver Bias
A 12.0k
Ω
(+/- 1%) resistor is attached from ground to this pin
to set the transceiver’s internal bias settings.