C9851 Datasheet, PDF (1/14 Pages) Cypress Semiconductor – Clock Generator for Pentium III Server and Workstation Applications

PRELIMINARY
C9851
Clock Generator for Pentium^III Server and Workstation Applications
Product Features
• Six pairs of current referenced differential clocks
• Two 3V 180° displaced Mref clocks for DRCG
• One 66.6 MHz reference output
• One 14.318 MHz reference output
• Select logic for Differential Swing Control, Test
mode, Hi-Z, Power-down, Spread spectrum, and
limited frequency select
• Cypress Spread Spectrum for EMI reduction
• 48 Pin SSOP Package
Frequency Selection Table
SEL 100/133 SELA SELB CPU(1:6), CPU#(1:6)
0
0
0
100 MHz
0
0
1
100 MHz
0
1
0
200 MHz
0
1
1
Hi-Z
1
0
0
133.3 MHz
1
0
1
25 MHz
1
1
0
200 MHz
1
1
1
REF/2
Block Diagram
Product Description
This device provides the necessary clocks for a
differential host bus system in multi-processor servers
and workstations. It also generates a 66.6MHz hub
clock for interfacing with a complimentary part, the
Cypress B9852. The 2 Mref clock outputs are 180
degrees out of phase and are used for interfacing with
the Direct Rambus Clock Generator (DRCG), C9820,
C9821, or C9822. This device integrates the Cypress
spread spectrum technology for optimum EMI
reduction.
3VMref,
3Vmref_b
50 MHz
Low
50 MHz
Hi-Z
66.67 MHz
50 MHz
66.7 MHz
REF/4
Table 1
3V66
66.67 MHz
Low
66.67 MHz
Hi-Z
66.67 MHz
66.67 MHz
66.67 MHz
REF
Pin Configuration
REF
14.318 MHz
Low
14.318 MHz
Hi-Z
14.318 MHz
14.318 MHz
14.318 MHz
REF
XIN _OSC
XOUT
MultSel(0:1)
Spread#
SelA
SelB
SEL100/133
VCO
PwrDwn#
I
Control
VDDR
REF
VSSR
VDDA
I_Ref
VSSI
CPU (1:6)
CPU (1:6)#
VDDM
3VMRef
3VMRef_b
VSSM
VDDL
3V66
VSSL
VSSR 1
Ref 2
VDDR 3
XIN 4
XOUT 5
VSSR 6
VDDM 7
3VMref 8
3VMref_b 9
VSSM 10
VDD 11
VSS 12
VDDL 13
3V66 14
VSSL 15
SEL100/133 16
MultSel0 17
MultSel1 18
VDDA 19
VSSA 20
SelA 21
SelB 22
Spread# 23
PwrDwn# 24
48
VDD
47
VSS
46
VDDC
45
CPU1
44
CPU1#
43
VSSC
42
CPU2
41
CPU2#
40
VDDC
39
CPU3
38
CPU3#
37
VSSC
36
CPU4
35
CPU4#
34
VDDC
33
CPU5
32
CPU5#
31
VSSC
30
CPU6
29
CPU6#
28
VDDC
27
I_Ref
26
VSSA
25
VDDA
Cypress Semiconductor Corporation
525 Los Coches St.
Milpitas, CA 95035. Tel: [phone], Fax: [phone]
http://www.cypress.com
Document#: 38-07068 Rev. **
05/04/2001
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