CDC950 Datasheet, PDF (3/16 Pages) Texas Instruments – 133-MHz DIFFERENTIAL CLOCK SYNTHESIZER/DRIVER FOR PC MOTHERBOARDS/SERVERS

CDC950
133ĆMHz DIFFERENTIAL CLOCK SYNTHESIZER/DRIVER FOR
PC MOTHERBOARDS/SERVERS
SCAS646B − FEBRUARY 2001 − REVISED OCTOBER 2003
Terminal Functions
TERMINAL
NAME
NO.
3V48/SelA,
3, 4
3V48/SelB
I/O
DESCRIPTION
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
AVDD3.3V
CLK33
GND
27, 45
P Analog ground
25, 46
P Power. Analog power supply
1
O 33-MHz reference clock for PCI use, host clock divided by 3 or by 4
5, 9, 15, P Ground
21, 28, 34,
40, 47
HCLK
7, 10, 13,
CPU and host clock outputs [7:0]. These eight differential CPU clock pairs run at 100/133 MHz. The VOH
16, 33, 36, O swing amplitude is configured by MultSel0, MultSel1 pins. See Table 5 and Intel’s CK00 document for
39, 42
details.
HCLK
I_REF
8, 11, 14,
CPU and host clock outputs [7:0]. These eight differential CPU clock pairs run at 100/133 MHz. The VOH
17, 32, 35, O swing amplitude is configured by MultSel0, MultSel1 pins. See Table 5 and Intel’s CK00 document for
38, 41
details.
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
MultSel1
PWRDWN
30
I See Table 5 and Intel’s CK00 document for details.
29
I See Table 5 and Intel’s CK00 document for details.
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
SEL100/133
19
O 14.138-MHz reference clock output: 3.3 V copy of the 14.318-MHz reference clock.
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, P Power. Power supply
18, 24, 31,
37, 43
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.
• POST OFFICE BOX 655303 DALLAS, TEXAS 75265
3