CDC950

133MHz DIFFERENTIAL CLOCK SYNTHESIZER/DRIVER FOR

PC MOTHERBOARDS/SERVERS

SCAS646B − FEBRUARY 2001 − REVISED OCTOBER 2003

3

POST OFFICE BOX 655303

Terminal Functions

TERMINAL

I/O

DESCRIPTION

NAME

NO.

I/O

DESCRIPTION

3V48/SelA,

3V48/SelB

3, 4

I/O

48-MHz 180

° shifted pair clocks for USB use

Logic select pins. Selects the mode of operation, see Table 1 for details.

AGND

27, 45

P

Analog ground

AVDD3.3V

25, 46

P

Power. Analog power supply

CLK33

1

O

33-MHz reference clock for PCI use, host clock divided by 3 or by 4

GND

5, 9, 15,

21, 28, 34,

40, 47

P

Ground

HCLK

7, 10, 13,

16, 33, 36,

39, 42

O

CPU and host clock outputs [7:0]. These eight differential CPU clock pairs run at 100/133 MHz. The VOH

swing amplitude is configured by MultSel0, MultSel1 pins. See Table 5 and Intel’s CK00 document for

details.

HCLK

8, 11, 14,

17, 32, 35,

38, 41

O

CPU and host clock outputs [7:0]. These eight differential CPU clock pairs run at 100/133 MHz. The VOH

swing amplitude is configured by MultSel0, MultSel1 pins. See Table 5 and Intel’s CK00 document for

details.

I_REF

26

I

Current reference. This pin establishes the reference current for host clock parts. See Table 5 and Intel’s

CK00 document for details.

MultSel0

30

I

See Table 5 and Intel’s CK00 document for details.

MultSel1

29

I

See Table 5 and Intel’s CK00 document for details.

PWRDWN

44

I

Power-down input. 3.3-V LVTTL compatible, asynchronous input that requests the device to enter the

power-down mode. See Table 2 for details.

REFCLK

19

O

14.138-MHz reference clock output: 3.3 V copy of the 14.318-MHz reference clock.

SEL100/133

48

I

Active low LVTTL level logic select. SEL100/133 is used for enabling 100/133 MHz. Low = 100 MHz, high

= 133 MHz

SPREAD

20

U

Spread spectrum enable. 3.3-V LVTTL compatible, input that enables the spread spectrum mode when

held low. See Table 4 for details.

VDD3.3V

2, 6, 12,

18, 24, 31,

37, 43

P

Power. Power supply

XIN

22

I

Crystal connection or an external reference frequency input. Connect to either a 14.138-MHz crystal or

an external reference signal.

XOUT

23

O

Crystal connection. An output connection for an external 14.318-MHz crystal. If using an external

reference, this pin must be left unconnected.