Datasheet

High-Speed Inter-Chip (HSIC) USB 2.0 Hub and Flash Media Controller
Datasheet
SMSC USB4640/USB4640i 13 Revision 1.3 (03-13-13)
DATASHEET
3.3 Pin Descriptions
This section provides a detailed description of each pin. The pins are arranged in functional groups
according to their associated interface. The pin descriptions below are applied when using the internal
default firmware and can be referenced in Chapter 4: Configuration Options on page 25. See
Appendix A: (Acronyms) on page 61 for details.
An n in the signal name indicates that the active (asserted) state occurs when the signal is at a low
voltage level. When the n is not present, the signal is asserted when it is at a high voltage level. The
terms assertion and negation are used exclusively in order 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 3.2 USB4640/USB4640i Pin Descriptions
SYMBOL
48-PIN
QFN
BUFFER
TYPE DESCRIPTION
UPSTREAM HSIC INTERFACE
HSIC_IMP 39 I HSIC Impedance Control
Selects the driver impedance of HSIC_DAT and HSIC_STROBE
1 : Approximately 50
Ω impedance
0 : Approximately 40 Ω impedance
HSIC_DAT 42 I/O HSIC Data
Bi-directional double data rate (DDR) data signal that is synchronous
to the HSIC_STROBE signal as defined in the High-Speed Inter-Chip
USB Specification, Version 1.0.
HSIC_STROBE 43 I/O HSIC Strobe
Bi-directional data strobe signal defined in the High-Speed Inter-Chip
USB Specification, Version 1.0.
DOWNSTREAM USB INTERFACE
USBDN_DM
[3:2]
USBDN_DP
[3:2]
3
1
4
2
I/O-U USB Bus Data
Connect to the downstream USB bus data signals and can be
swapped using the PortSwap feature (See Section 4.4.4.20: F1h:
Port Swap on page 43).
PRTCTL[3:2] 7
6
I/OD6PU USB Power Enable, when used as an:
 output: enables power to downstream USB peripheral devices and
have weak internal pull-up resistors. (See Section 3.5: Port Power
Control on page 20 for diagram and usage instructions.)
 input: monitor the over-current condition (when the power is
enabled). When an over-current condition is detected, the pins turn
the power off.
RBIAS 47 I-R USB Transceiver Bias
Sets the transceiver's internal bias currents using a 12.0 kΩ, ±1.0%
resistor attached from VSS.
XTAL1 (CLKIN) 45 ICLKx 24 MHz Crystal Input or External Clock Input
Can be connected to one terminal of the crystal or connected to an
external 24 MHz clock when a crystal is not used.