鈥?/div>
Output Frequency up to 125MHz
TM
TM
Processors
Supports Power PC , and Pentium
15 Clock Output: Frequency Configurable
Two Reference Clock Inputs for Dynamic Toggling
Output Tri-State Control
Spread Spectrum Compatible
3.3V Power Supply
Pin Compatible with MPC974
Industrial Temp. Range: -40擄C to +85擄C
52 Pin TQFP Package
Feedback Ratio Selection Table
Inputs
VCO_Sel
0
0
0
0
1
1
1
1
fselFB0
0
0
1
1
0
0
1
1
fselFB1
0
1
0
1
0
1
0
1
Outputs
QFB
VCO/8
VCO/12
VCO/16
VCO/24
VCO/16
VCO/24
VCO/32
VCO/48
Table 1
Product Description
The Z9974 is a low cost 3.3V zero delay clock driver for
high speed signal buffering and redistribution.
It provides the designer with the flexibility of selecting
various Output/Input Frequency ratios selected by fsela,
fselb, fselc, fselFB(0:1), and VCO_sel input settings.
The Z9974 integrates PLL technology for Zero delay
propagation from Input to Output. The PLL feedback is
externally available for propagation delay tuning and
divide ratio alternatives as per table 1.
The Z9974 has three banks of outputs with independent
divider stages. These dividers allow the banks to have
different frequencies as per table 2.
TCLK0 and TCLK1 one are selectable input reference
clocks and may be toggled dynamically during operation
to provide modulation and phase shifting designs.
This device includes a Master Reset signal, which
disables the outputs into Tristate (Hi-Z) mode, and reset
all internal digital circuitry (excluding the PLL).
An Output Enable, OE, input pin is available for shutting
Qa(0:4), Qb(0:4), and Qc(0:3) outputs in a low state. All
outputs are held low with input clock turned off.
Pin Configuration
Qb0
VDDb
NC
VSSc
Qc3
VDDc
QC2
VSSc
QC1
VDDc
QC0
VSSc
VCO_Sel
52 51 50 49 48 47 46 45 44 43 42 41 40
VSSA
MR#
OE
fselb
fselc
PLL_EN
fsela
TClk_Sel
TClk0
TClk1
NC
VDDI
VDDA
1
2
3
4
5
6
7
8
9
10
11
12
13
39
38
37
36
35
34
33
32
31
30
29
28
27
VSSb
QB1
VDDb
Qb2
VSSb
Qb3
VDDb
Qb4
FB_IN
VSSFB
QFB
VDDFB
NC
Z9974
14 15 16 17 18 19 20 21 22 23 24 25 26
VDDa
Qa0
VSSa
Qa1
VDDa
Qa2
fselFB1
VSSa
Qa3
VDDa
Qa4
VSSI
fselFB0
Cypress Semiconductor Corporation
525 Los Coches St.
Milpitas, CA 95035. Tel: 408-263-6300, Fax: 408-263-6571
http://www.cypress.com
Document#: 38-07090 Rev. *A
06/18/2001
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