2-Port USB 2.0 Hi-Speed Hub Controller

Datasheet

Revision 1.3 (12-27-11)

12

SMSC USB2412

DATASHEET

2.4

Buffer Type Descriptions

2.5

Strap Option Pins

The NON_REM[1:0] strap option pins can be enabled using the internal default configuration. The

driver type of each strap pin is I/O (no internal pull-up or pull-down for the input function). Figure 2.2

shows an example of Strap High and Strap Low configurations, where Strap High sets the strap option

to a 1 and Strap Low sets the strap option value to 0. To use an external LED indicator, the options

outlined in Figure 2.3 should be implemented.

Figure 2.2 Non-Removable Pin Strap Example

29

ePAD

Ground Pad/ePad: this pin must be connected to VSS for the device

and must be tied to ground with multiple vias

5

NC

No Connect: no signal or trace should be routed or attached to these

pins.

Table 2.3 Buffer Type Descriptions

BUFFER

DESCRIPTION

I/O

Input/Output

IPD

Input with internal weak pull-down resistor

IPU

Input with internal weak pull-up resistor

IS

Input with Schmitt trigger

I/O12

Input/Output buffer with 12 mA sink and 12 mA source

ICLKx

XTAL clock input

OCLKx

XTAL clock output

I-R

RBIAS

I/O-U

Analog Input/Output defined in USB specification

Table 2.2 USB2412 Pin Descriptions (continued)

PIN

#

SYMBOL

BUFFER

TYPE

DESCRIPTION

HUB

Strap Pin

Primary Function/

Strap High

+V

HUB

Strap Pin

Primary Function/

Strap Low

GND

50 k

Ω

50 k

Ω