USB2422

DS00001726B-page 10

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.

POWER, GROUND, and NO CONNECTS

1

9

18

VDD33

3.3 V power to the chip.

A 1.0

μF low-ESR capacitor to VSS is required on pin 9 as close as

possible to the pin. A 0.1

μF low-ESR capacitor to VSS is required on

pin 1 as close as possible to the pin.

10

CRFILT

VDD Core Regulator Filter Capacitor:

This pin requires a 1.0

μF low-ESR capacitor to VSS for proper

operation.

23

PLLFILT

PLL Regulator Filter Capacitor:

This pin can have up to a 0.1

μF low-ESR capacitor to VSS, or be left

unconnected.

VSS

Ground Pad/ePad:

The package slug is the only VSS for the device and must be tied to

ground with multiple vias.

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 2-4:

STRAP OPTION SUMMARY

Strap Option

Resistor Value

Buffer Type

Notes

Non-Removable

47 - 100 k

Ω

I/O

Internal Pull-Down (IPD)

10 k

Ω

IPD

• Only applicable to port power pins

• Contains a built-in resistor

LED

47 - 100 k

Ω

I/O

TABLE 2-2:

USB2422 PIN DESCRIPTIONS (CONTINUED)

Pin #

Symbol

Buffer Type

Description