CY28409

Rev 1.0, November 22, 2006

Page 2 of 16

Pin Description

Pin No.

Name

Type

Description

1, 2

REF(0:1)

O, SE Reference Clock. 3.3V 14.318-MHz clock output.

4XIN

I

Crystal Connection or External Reference Frequency Input. This pin has dual

functions. It can be used as an external 14.318-MHz crystal connection or as an external

reference frequency input.

5

XOUT

O, SE Crystal Connection. Connection for an external 14.318-MHz crystal output.

41,44,47

CPUT(0:2)

O, DIF CPU Clock Output. Differential CPU clock outputs. See Table 1 for frequency config-

uration.

40,43,46

CPUC(0:2)

O, DIF CPU Clock Output. Differential CPU clock outputs. See Table 1 for frequency config-

uration.

38, 37

SRCT, SRCC

O, DIF Differential serial reference clock.

22,23,26,27

3V66(0:3)

O, SE 66-MHz Clock Output. 3.3V 66-MHz clock from internal VCO.

29

3V66_4VCH

O, SE 48-/66-MHz Clock Output. 3.3V selectable through SMBus to be 66 or 48 MHz.

7,8,9

PCIF(0:2)

O, SE Free-running PCI Output. 33-MHz clocks divided down from 3V66.

12,13,14,

15,18,19,20

PCI(0:6)

O, SE PCI Clock Output. 33-MHz clocks divided down from 3V66.

31,

USB_48

O, SE Fixed 48-MHz clock output.

32

DOT_48

O, SE Fixed 48-MHz clock output.

51,56

FS_A, FS_B

I

3.3V LVTTL input for CPU frequency selection.

52

IREF

I

Current Reference. A precision resistor is attached to this pin which is connected to

the internal current reference.

21

PD#

I, PU

3.3V LVTTL input for Power-Down# active LOW.

50

CPU_STP#

I, PU

3.3V LVTTL input for CPU_STP# active LOW.

49

PCI_STP#

I, PU

3.3V LVTTL input for PCI_STP# active LOW.

35

VTT_PWRGD#

I

3.3V LVTTL input is a level sensitive strobe used to latch the FS_A and FS_B

inputs (active LOW).

30

SDATA

I/O

SMBus-compatible SDATA.

28

SCLK

I

SMBus-compatible SCLOCK.

53

VSS_IREF

GND

Ground for current reference.

55

VDD_A

PWR

3.3V power supply for PLL.

54

VSS_A

GND

Ground for PLL.

42,48

VDD_CPU

PWR

3.3V power supply for outputs.

45

VSS_CPU

GND

Ground for outputs.

36

VDD_SRC

PWR

3.3V power supply for outputs.

39

VSS_SRC

GND

Ground for outputs.

34

VDD_48

PWR

3.3V power supply for outputs.

33

VSS_48

GND

Ground for outputs.

10,16

VDD_PCI

PWR

3.3V power supply for outputs.

11,17

VSS_PCI

GND

Ground for outputs.

24

VDD_3V66

PWR

3.3V power supply for outputs.

25

VSS_3V66

GND

Ground for outputs.

3

VDD_REF

PWR

3.3V power supply for outputs.

6

VSS_REF

GND

Ground for outputs.