USB2412 datasheet(10/27 Pages) SMSC

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2-Port USB 2.0 Hi-Speed Hub Controller

Datasheet

Revision 1.3 (12-27-11)

SMSC USB2412

DATASHEET

2.3

Pin Descriptions (Grouped by Function)

Table 2.2 USB2412 Pin Descriptions

SYMBOL

BUFFER

TYPE

DESCRIPTION

UPSTREAM USB 2.0 INTERFACES

USBDM_UP

USBDP_UP

IO-U

USB Bus Data: connect to the upstream USB bus data signals (host,

port, or upstream hub).

VBUS_DET

I/O12

Detect Upstream VBUS Power: detects the state of upstream VBUS

power. The SMSC hub monitors VBUS_DET to determine when to

assert the internal D+ pull-up resistor which signals a connect event.

When designing a detachable hub, this pin should be connected to

VBUS on the upstream port via a 2 to 1 voltage divider.

For self-powered applications with a permanently attached host, this

pin must be connected to a dedicated host control output, or

connected to 3.3 V domain that powers the host.‘

According to Section 7.2.1 of the USB 2.0 Specification 1., a

downstream port can never provide power to its D+ or D- pull-up

resistors unless the upstream port’s VBUS is in the asserted (powered)

state.

VBUS_DET monitors the state of the upstream VBUS signal and will

not pull-up the D+ resistor if VBUS is not active. If VBUS goes from

an active to an inactive state (Not Powered), the hub will remove

power from the D+ pull-up resistor within 10 seconds.

DOWNSTREAM USB 2.0 INTERFACES

USBDP_DN1

USBDP_DN2

USBDM_DN1

USBDM_DN2

IO-U

Hi-Speed USB Data: connect to the downstream USB peripheral

devices attached to the hub’s ports.

PRTPWR1

PRTPWR2

I/O12

USB Power Enable: enables power to USB peripheral devices that are

downstream, where the hub supports active high power controllers

only.

OCS_N1

OCS_N2

IPU

Over-Current Sense: input from external current monitor indicating an

over-current condition. This pin contains an internal pull-up to the 3.3 V

supply.

RBIAS

I-R

USB Transceiver Bias: a 12.0 k

Ω (+/- 1%) resistor is attached from

ground to this pin to set the transceiver’s internal bias settings.

MISC

NON_REM1

I/O

Non-removable Port Strap Option: this pin is sampled (in conjunction

with SUSP_IND/NON_REM0) at RESET_N negation to determine if

ports [2:1] contain permanently attached (non-removable) devices:

NON_REM[1:0] = 00: all ports are removable

NON_REM[1:0] = 01: port 1 is non-removable

NON_REM[1:0] = 10 and 11: ports 1 and 2 are non-removable

See Section 2.5, "Strap Option Pins" for details.

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