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Cypress Semiconductor Electronic Components Datasheet

C9851 Datasheet

Clock Generator

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C9851 pdf
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PRELIMINARY
C9851
Clock Generator for PentiumIII 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 00
100 MHz
0 01
100 MHz
0 10
200 MHz
0 11
Hi-Z
1 0 0 133.3 MHz
1 01
25 MHz
1 10
200 MHz
1 11
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
Ref
VDDR
XIN
XOUT
VSSR
VDDM
3VMref
3VMref_b
VSSM
VDD
VSS
VDDL
3V66
VSSL
SEL100/133
MultSel0
MultSel1
VDDA
VSSA
SelA
SelB
Spread#
PwrDwn#
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
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: 408-263-6300, Fax: 408-263-6571
http://www.cypress.com
Document#: 38-07068 Rev. **
05/04/2001
Page 1 of 14


Cypress Semiconductor Electronic Components Datasheet

C9851 Datasheet

Clock Generator

No Preview Available !

C9851 pdf
PRELIMINARY
C9851
Clock Generator for PentiumIII Server and Workstation Applications
Pin Description
PIN No.
Pin Name
I/O Description
8
3VMref
O Output clock for driving the DRCG device. See table 1, page1 for frequency selection.
9
23
45,42,39,36,
33,30
44,41,38,35,
32,29
3VMref_b
Spread#
CPU(1:6)
CPU(1:6)#
O Output clock for driving the DRCG device. See table 1, page1 for frequency selection. It
is 180 degrees out of phase (inverted) from the 3VMref clock.
PU When asserted low, this pin invokes Spread Spectrum functionality. Spread spectrum is
applicable to CPU(1:6), CPU(1:6)#, 3VMref, 3VMref_b, and 3V66 clocks. This pin has a
250Kinternal Pull-up.
O Differential host clock outputs. These outputs are used in pairs, (CPU1-1#, CPU2-2#,
CPU3-3#, CPU4-4#, CPU5-5#, and CPU6-6#) for differential clocking of the host bus.
CPU(1:6)# are 180 degrees out of phase with their complements, CPU(1:6). See table 1,
page 1 for frequency selection.
27
I_Ref
P This pin establishes the reference current for the internal current steering buffers of the
CPU clocks. A resistor is connected from this pin to ground to set the value of this current.
See applications data on page 9 of this data sheet for details.
14
3V66
O Fixed 66.67 MHz clock output for driving the IMI B9852 buffer device.
24
22, 21
16
5
4
PwrDwn#
SelA, SelB
SEL100/133
XOUT
XIN
PU When asserted low, this pin Invokes power-down mode by shutting off all the clocks,
disabling all internal circuitry, and shutting down the crystal oscillator. The 3VMref,
3VMref_B, 3V66, REF and CPU clocks are driven low during this condition. It has a
250Kinternal Pull-up.
PD Input select pins. See table 1, page 1. Each pin has a 250Kinternal Pull-down
PU Input select pin. See table 1, page 1. It has a 250Kinternal Pull-up
O Crystal Buffer output pin. Connects to a crystal only. When an external signal other than
a crystal is used or when in Test mode, this pin is kept unconnected.
I Crystal Buffer input pin. Connects to a crystal, or an external single ended input clock
signal.
2
18, 17
3
REF
MultSel (0,1)
VDDR
O A buffered output clock of the signal applied at Xin. Typically, 14.31818MHz.
I These input select pins configure the LOH current (and thus the VOH swing amplitude) of
the CPU clock output pairs. Each pin has a 250Kinternal Pull-up. See the table 5 for
current and resistor values.
P 3.3V power supply pins for Ref clock and crystal buffer.
46,40,34,28
11, 48
VDDC
VDD
P 3.3V power supply pins for CPU(1:6) / CPU(1:6)# outputs.
P 3.3V power supply pins for common supply to the core.
13
19, 25
VDDL
VDDA
P 3.3V power supply pins for 3V66 output.
P 3.3V power supply pins for internal current reference circuitry and internal PLL.
7
1, 6
31, 37, 43
VDDM
VSSR
VSSC
P 3.3V power supply pin for 3Vmref and 3Vmref_b outputs
P Ground pins for the Ref clock and crystal buffer.
P Ground pins for the CPU(1:6)/CPU(1:6)# outputs.
12, 47
15
VSS
VSSL
P Ground pins for common supply to the core.
P Ground pin for the 3V66 output.
20, 26
10
VSSA
VSSM
P Ground pin for internal current reference circuitry and internal PLL.
P Ground pin for 3Vmref and 3Vmref_b outputs.
Note: Definition of I/O column pneumonic on pin description table above:
I = Input pin, O = output pin, P = power supply pin, PU = This indicated that a bi-directional pin contains a device internal pull-up
resistor. This will insure that this pin of the device will be seen by the internal logic as a logic 1 level. Likewise pins with a PD
designation are guaranteed to be seen as a logic 0 level if no external level setting circuitry is present at power up.
Cypress Semiconductor Corporation
525 Los Coches St.
Milpitas, CA 95035. Tel: 408-263-6300, Fax: 408-263-6571
http://www.cypress.com
Document#: 38-07068 Rev. **
05/04/2001
Page 2 of 14


Part Number C9851
Description Clock Generator
Maker Cypress Semiconductor
Total Page 14 Pages
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