2

PS8887B

10/19/07

PI6C20800S

PCI Express 1:8

HCSL Clock Buffer

Pin Descriptions

Pin Name

Type

Pin #

Descriptions

SRC_DIV#

Input

1

3.3V LVTTL input for selecting input frequency divide by 2,

active LOW.

SRC & SRC#

Input

4, 5

0.7V Differential SRC input from PI6C410 clock synthesizer

OE [0:7]

Input

6, 7, 14, 15, 35, 36,

43, 44

3.3V LVTTL input for enabling outputs, active HIGH.

OE_INV

Input

40

3.3V LVTTL input for inverting the OE, SRC_STOP# and

PWRDWN# pins.

When 0 = same stage

When 1 = OE[0:7], SRC_STOP#, PWRDWN# inverted.

OUT[0:7] & OUT[0:7]#

Output

8, 9, 12, 13, 16 17,

20, 21, 29, 30, 33, 34,

37, 38, 41, 42

0.7V Differential outputs

PLL/BYPASS#

Input

22

3.3V LVTTL input for selecting fan-out of PLL operation.

SCLK

Input

23

SMBus compatible SCLOCK input

SDA

I/O

24

SMBus compatible SDATA

Input

46

External resistor connection to set the differential output current

SRC_STOP#

Input

27

3.3V LVTTL input for SRC stop, active LOW

PLL_BW#

Input

28

3.3V LVTTL input for selecting the PLL bandwidth

PWRDWN#

Input

26

3.3V LVTTL input for Power Down operation, active LOW

LOCK

Output

45

3.3V LVTTL output, transition high when PLL lock is achieved

(Latched output)

Power

2, 11, 19, 31, 39

3.3V Power Supply for Outputs

Ground

3, 10, 18, 25, 32

Ground for Outputs

Ground

47

Ground for PLL

Power

48

3.3V Power Supply for PLL

Serial Data Interface (SMBus)

PI6C20800S is a slave only SMBus device that supports indexed block read and indexed block write protocol using a single 7-bit

address and read/write bit as shown below.

Address assignment

A6

A5

A4

A3

A2

A1

A0

R/W

110

1

1

1

0

0/1

1 bit

7 bits

1

1

8 bits

1

8 bits

1

8 bits

1

8 bits

1

1 bit

Start

bit

Slave

Addr

R/W

Ack

Register

offset

Ack

Byte

Count

= N

Ack

Data

Byte 0

Ack

Data

Byte N

- 1

Ack

Stop

bit

Note:

1.

Register offset for indicating the starting register for indexed block write and indexed block read. Byte Count in write mode cannot be 0.

07-0237