2

PS8824C

12/14/07

PI6C557-03

PCI Express Clock

Pin Description

Pin #

Pin Name

I/O Type

Description

1

S0

Input

Select pin 0 (Internal pull-up resistor). See Table 1.

2

S1

Input

Select pin 1 (Internal pull-up resistor). See Table 1.

3

SS0

Input

Spread Select pin 0 (Internal pull-up resistor). See Table 2.

4

X1/CLK

Input

Crystal or clock input. Connect to a 25MHz crystal or single ended clock.

5

X2

Output

Crystal connection. Leave unconnected for clock input.

6

OE

Input

Output enable. Internal pull-up resistor.

7

GNDX

Power

Crystal ground pin.

8

SS1

Input

Spread Select pin 1 (Internal pull-up resistor). See Table 2.

9

IREF

Output

Precision resistor attached to this pin is connected to the internal current reference.

10

CLK1

Output

HCSL compliment clock output

11

CLK1

Output

HCSL clock output

12

VDDA

Power

Connect to a +3.3V source.

13

GNDA

Power

Output and analog circuit ground.

14

CLK0

Output

HCSL compliment clock output

15

CLK0

Output

HCSL clock output

16

VDDX

Power

Connect to a +3.3V source.

Table 1: Output Select Table

S1

S0

CLK(MHz)

00

25

0

1

100

1

0

125

1

1

200

Table 2: Spread Selection Table

SS1

SS0

Spread

0

0

Center ±0.25

0

1

Down -0.5

1

0

Down -0.75

1

1

No Spread

07-0274