USB2422 datasheet(14/51 Pages) SMSC

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2-Port USB 2.0 Hi-Speed Hub Controller

Datasheet

Revision 1.0 (06-04-13)

SMSC USB2422

DATASHEET

2.4

Buffer Type Descriptions

2.5

Strap Pin Configuration

If a pin's strap function is enabled through hub configuration selection (Table 4.1), the strap pins must

be pulled either high or low using the values provided in Table 2.4. Each strap option is dependent on

the pin’s buffer type, as outlined in the sections that follow.

2.5.1

Non-Removable

If a strap pin’s buffer type is I/O, an external pull-up or pull-down must be implemented as shown in

Figure 2.2. Use Strap High to set the strap option to 1 and Strap Low to set the strap option to 0. When

implementing the Strap Low option, no additional components are needed (i.e., the internal pull-down

provides the resistor)

Figure 2.2 Non-Removable Pin Strap Example

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

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 2.4 Strap Option Summary

STRAP OPTION

RESISTOR VALUE

BUFFER TYPE

NOTES

Non-Removable

47 - 100 k

I/O

Internal Pull-Down

(IPD)

10 k

IPD



Only applicable to port power pins



Contains a built-in resistor

LED

47 - 100 k

I/O

HUB

I/O Strap Pin

Strap High

HUB

I/O Strap Pin

Strap Low

GND

R k

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