CY28447
Pin Description (continued)
Pin No.
Name
Type
Description
39
VTT_PWRGD#/PD
I, PD 3.3V LVTTL input. This pin is a level sensitive strobe used to latch the FSA, FSB,
FSC, FCTSEL1, and ITP_SEL. After VTT_PWRGD# (active LOW) assertion, this
pin becomes a real-time input for asserting power down (active HIGH).
40
41
VDD_48
PWR 3.3V power supply for outputs.
48M/FSA
I/O
Fixed 48-MHz clock output / 3.3V-tolerant input for CPU frequency selection
Refer to DC Electrical Specifications table for Vil_FS and Vih_FS specifications.
42
VSS_48
GND Ground for outputs.
43, 44
DOT96T/ 27M_NSS
DOT96C/ 27M_SS
O, DIF Fixed 96-MHz clock output or 27 Mhz Spread and Non-spread output
Selected via FCTSEL1 at VTTPWRGD# assertion.
45
FSB/TEST_MODE
I
3.3V-tolerant input for CPU frequency selection. Selects Ref/N or Tri-state
when in test mode
0 = Tri-state, 1 = Ref/N
Refer to DC Electrical Specifications table for Vil_FS and Vih_FS specifications.
47, 48
SRC[T/C]0/
LCD100M[T/C]
O,DIF 100 MHz differential serial reference clock output / Differential 96/100-MHz
SS clock for flat-panel display
Selected via FCTSEL1 at VTTPWRGD# assertion.
initialize to their default setting upon power-up, and therefore
Frequency Select Pins (FSA, FSB, and FSC)
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.
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
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.
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.
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
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)
Table 1. Frequency Select Table FSA, FSB, and FSC[1]
FSC FSB FSA
CPU
SRC
PCIF/PCI
33 MHz
33 MHz
33 MHz
33 MHz
27MHz
27 MHz
27 MHz
27 MHz
27 MHz
REF0
DOT96
96 MHz
96 MHz
96 MHz
96 MHz
USB
1
0
0
0
0
0
1
1
1
1
1
0
100 MHz
133 MHz
166 MHz
200 MHz
100 MHz
100 MHz
100 MHz
100 MHz
14.318 MHz
14.318 MHz
14.318 MHz
14.318 MHz
48 MHz
48 MHz
48 MHz
48 MHz
.
Table 2. Command Code Definition
Bit
Description
7
0 = Block read or block write operation, 1 = Byte read or byte write operation
(6:0)
Byte offset for byte read or byte write operation. For block read or block write operations, these bits should be
'0000000'
Note:
1. 27-MHz and 96-MHz can not be output at the same time.
Rev 1.0,November 20, 2006
Page 3 of 21
SPECTRALINEAR [ SPECTRALINEAR INC ]
