CY28443-3
Pin Descriptions
(continued)
Pin No.
52
Name
REF1/FCTSEL0
Type
Description
I/O, SE
Fixed 14.318-MHz Clock Output/3.3 LVTTL input for selecting for pin 14, 15
PD
(DOT96[T/C], 27M-non-spread and Spread) and pin 17,18 (SRC[T/C]0 or
100M[T/C]_SST)
(sampled on the VTT_PWRGD# assertion).
FCTSEL1 FCTSEL0 PIN 14
PIN 15
0
0
DOT96T
DOT96C
0
1
DOT96T
DOT96C
1
0
27M_non spread 27M_Spread
1
1
OFF Low
TBD
PIN 17
100MT_SST
SRCT0
SRCT0
SRCT0
PIN 18
100MC_SST
SRCC0
SRCC0
SRCC0
53
FSC
I/O
3.3V-tolerant input for CPU frequency selection.
Refer to DC Electrical Specification Table for VilFS_C, VimFS_C and VihFS_C
specifications
3.3V LVTTL input for CPU_STP# active LOW.
3.3V LVTTL input for PCI_STP# active LOW.
54
55
56
CPU_STP#
PCI_STP#
I, PU
I, PU
PCI2/SEL_CLKREQ# I/O, PD
Fixed 33-MHz clock output/3.3V-tolerant input for CLKREQ# pins 32 and 33
SE
selection
(sampled on the VTT_PWRGD# assertion).
0 = CLKREQ#[A:B] functionality
1 = SRC[T/C]9 functionality
Table 1. Frequency Select Table FSA, FSB and FSC
FSC
1
0
0
0
FSB
0
0
1
1
FSA
1
1
1
0
CPU
100 MHz
133 MHz
166 MHz
200 MHz
SRC
100 MHz
100 MHz
100 MHz
100 MHz
PCIF/PCI
33 MHz
33 MHz
33 MHz
33 MHz
27MHz
27 MHz
27 MHz
27 MHz
27 MHz
REF0
14.318 MHz
14.318 MHz
14.318 MHz
14.318 MHz
DOT96
96 MHz
96 MHz
96 MHz
96 MHz
USB
48 MHz
48 MHz
48 MHz
48 MHz
Frequency Select Pins (FSA, FSB, and FSC)
Host clock frequency selection is achieved by applying the
appropriate logic levels to FSA, FSB, FSC inputs prior to
VTT_PWRGD# assertion (as seen by the clock synthesizer).
Upon VTT_PWRGD# being sampled low by the clock chip
(indicating processor VTT voltage is stable), the clock chip
samples the FSA, FSB, and FSC input values. For all logic
levels of FSA, FSB, and FSC, VTT_PWRGD# employs a
one-shot functionality in that once a valid low on
VTT_PWRGD# has been sampled, all further VTT_PWRGD#,
FSA, FSB, and FSC transitions will be ignored, except in test
mode.
initialize to their default setting upon power-up, and therefore
use of this interface is optional. Clock device register changes
are normally made upon system initialization, if any are
required. The interface cannot be used during system
operation for power management functions.
Data Protocol
The clock driver serial protocol accepts byte write, byte read,
block write, and block read operations from the controller. For
block write/read operation, the bytes must be accessed in
sequential order from lowest to highest byte (most significant
bit first) with the ability to stop after any complete byte has
been transferred. For byte write and byte read operations, the
system controller can access individually indexed bytes. The
offset of the indexed byte is encoded in the command code,
as described in
Table 2.
The block write and block read protocol is outlined in
Table 3
while
Table 4
outlines the corresponding byte write and byte
read protocol. The slave receiver address is 11010010 (D2h).
Serial Data Interface
To enhance the flexibility and function of the clock synthesizer,
a two-signal serial interface is provided. Through the Serial
Data Interface, various device functions, such as individual
clock output buffers, can be individually enabled or disabled.
The registers associated with the Serial Data Interface
Table 2. Command Code Definition
Bit
7
(6:0)
Description
0 = Block read or block write operation, 1 = Byte read or byte write operation
Byte offset for byte read or byte write operation. For block read or block write operations, these bits should be
'0000000'
Rev 1.0, November 20, 2006
Page 3 of 23
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