CY28409
Clock Synthesizer with Differential SRC and CPU Outputs
Features
• Supports Intel
Pentium
4-type CPUs
• Selectable CPU frequencies
• 3.3V power supply
• Ten copies of PCI clocks
• Five copies of 3V66 with one optional VCH
• Two copies 48 MHz USB clocks
CPU
x3
SRC
x1
3V66
x5
PCI
x 10
REF
x2
48M
x2
• Three differential CPU clock pairs
• One differential SRC clock
• I
2
C support with readback capabilities
• Ideal Lexmark Spread Spectrum profile for maximum
EMI reduction
• 56-pin SSOP and TSSOP packages
Block Diagram
XIN
XOUT
CPU_STP#
PCI_STP#
FS_[A:B]
VTT_PWRGD#
IREF
VDD_3V66
3V66_[0:3]
Pin Configuration
VDD_REF
REF0:1
[1]
XTAL
OSC
PLL1
~
PLL Ref Freq
Divider
Network
VDD_CPU
CPUT[0:2], CPUC[0:2]
VDD_SRC
SRCT, SRCC
PLL2
2
VDD_PCI
PCIF[0:2]
PCI[0:6]
3V66_4/VCH
VDD_48MHz
DOT_48
USB_48
PD#
SDATA
SCLK
I
2
C
Logic
REF_0
REF_1
VDD_REF
XIN
XOUT
VSS_REF
PCIF0
PCIF1
PCIF2
VDD_PCI
VSS_PCI
PCI0
PCI1
PCI2
PCI3
VDD_PCI
VSS_PCI
PCI4
PCI5
PCI6
PD#
3V66_0
3V66_1
VDD_3V66
VSS_3V66
3V66_2
3V66_3
SCLK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
FS_B
VDD_A
VSS_A
VSS_IREF
IREF
FS_A
CPU_STP#
PCI_STP#
VDD_CPU
CPUT2
CPUC2
VSS_CPU
CPUT1
CPUC1
VDD_CPU
CPUT0
CPUC0
VSS_SRC
SRCT
SRCC
VDD_SRC
VTT_PWRGD#
VDD_48
VSS_48
DOT_48
USB_48
SDATA
3V66_4/VCH
56 SSOP/TSSOP
CY28409
Note:
1. Signals marked with [*] and [**] have internal pull-up and pull-down resistors, respectively.
........................ Document #: 38-07445 Rev. *D Page 1 of 16
400 West Cesar Chavez, Austin, TX 78701
1+(512) 416-8500
1+(512) 416-9669
www.silabs.com
CY28409
Pin Description
Pin No.
1, 2
4
XIN
Name
REF(0:1)
Type
I
Description
Crystal Connection or External Reference Frequency Input.
This pin has dual
functions. It can be used as an external 14.318-MHz crystal connection or as an external
reference frequency input.
O, SE
Reference Clock.
3.3V 14.318-MHz clock output.
5
41,44,47
40,43,46
38, 37
22,23,26,27
29
7,8,9
12,13,14,
15,18,19,20
31,
32
51,56
52
21
50
49
35
30
28
53
55
54
42,48
45
36
39
34
33
10,16
11,17
24
25
3
6
XOUT
CPUT(0:2)
CPUC(0:2)
SRCT, SRCC
3V66(0:3)
3V66_4VCH
PCIF(0:2)
PCI(0:6)
USB_48
DOT_48
FS_A, FS_B
IREF
PD#
CPU_STP#
PCI_STP#
VTT_PWRGD#
SDATA
SCLK
VSS_IREF
VDD_A
VSS_A
VDD_CPU
VSS_CPU
VDD_SRC
VSS_SRC
VDD_48
VSS_48
VDD_PCI
VSS_PCI
VDD_3V66
VSS_3V66
VDD_REF
VSS_REF
O, SE
Crystal Connection.
Connection for an external 14.318-MHz crystal output.
O, DIF
CPU Clock Output.
Differential CPU clock outputs. See
Table 1
for frequency config-
uration.
O, DIF
CPU Clock Output.
Differential CPU clock outputs. See
Table 1
for frequency config-
uration.
O, DIF
Differential serial reference clock.
O, SE
66-MHz Clock Output.
3.3V 66-MHz clock from internal VCO.
O, SE
48-/66-MHz Clock Output.
3.3V selectable through SMBus to be 66 or 48 MHz.
O, SE
Free-running PCI Output.
33-MHz clocks divided down from 3V66.
O, SE
PCI Clock Output.
33-MHz clocks divided down from 3V66.
O, SE
Fixed 48-MHz clock output.
O, SE
Fixed 48-MHz clock output.
I
I
I, PU
I, PU
I, PU
I
I/O
I
GND
PWR
GND
PWR
GND
PWR
GND
PWR
GND
PWR
GND
PWR
GND
PWR
GND
3.3V LVTTL input for CPU frequency selection.
Current Reference.
A precision resistor is attached to this pin which is connected to
the internal current reference.
3.3V LVTTL input for Power-Down# active LOW.
3.3V LVTTL input for CPU_STP# active LOW.
3.3V LVTTL input for PCI_STP# active LOW.
3.3V LVTTL input is a level sensitive strobe used to latch the FS_A and FS_B
inputs
(active LOW).
SMBus-compatible SDATA.
SMBus-compatible SCLOCK.
Ground for current reference.
3.3V power supply for PLL.
Ground for PLL.
3.3V power supply for outputs.
Ground for outputs.
3.3V power supply for outputs.
Ground for outputs.
3.3V power supply for outputs.
Ground for outputs.
3.3V power supply for outputs.
Ground for outputs.
3.3V power supply for outputs.
Ground for outputs.
3.3V power supply for outputs.
Ground for outputs.
........................Document #: 38-07445 Rev. *D Page 2 of 16
CY28409
Table 1. Frequency Select Table (FS_A, FS_B)
FS_A
0
0
0
1
1
FS_B
0
MID
1
0
MID
CPU
100 MHz
REF/N
200 MHz
133 MHz
Hi-Z
SRC
100/200 MHz
REF/N
100/200 MHz
100/200 MHz
Hi-Z
3V66
66 MHz
REF/N
66 MHz
66 MHz
Hi-Z
PCIF/PCI
33 MHz
REF/N
33 MHz
33 MHz
Hi-Z
REF0
14.3 MHz
REF/N
14.3 MHz
14.3 MHz
Hi-Z
REF1
14.31 MHz
REF/N
14.31 MHz
14.31 MHz
Hi-Z
USB/DOT
48 MHz
REF/N
48 MHz
48 MHz
Hi-Z
Table 2. Frequency Select Table (FS_A, FS_B) SMBus Bit 5 of Byte 6 = 1
FS_A
0
0
1
FS_B
0
1
0
CPU
200 MHz
400 MHz
266 MHz
SRC
100/200 MHz
100/200 MHz
100/200 MHz
3V66
66 MHz
66 MHz
66 MHz
PCIF/PCI
33 MHz
33 MHz
33 MHz
REF0
14.3 MHz
14.3 MHz
14.3 MHz
REF1
14.31 MHz
14.31 MHz
14.31 MHz
USB/DOT
48 MHz
48 MHz
48 MHz
Frequency Select Pins (FS_A, FS_B)
Host clock frequency selection is achieved by applying the
appropriate logic levels to FS_A and FS_B 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 FS_A and FS_B input values. For all logic levels
of FS_A and FS_B except MID, VTT_PWRGD# employs a
one-shot functionality in that once a valid LOW on
VTT_PWRGD# has been sampled LOW, all further
VTT_PWRGD#, FS_A and FS_B transitions will be ignored. In
the case where FS_B is at mid level when VTT_PWRGD# is
sampled LOW, the clock chip will assume “Test Clock Mode.”
Once “Test Clock Mode” has been invoked, all further FS_B
transitions will be ignored and FS_A will asynchronously
select between the Hi-Z and REF/N mode. Exiting test mode
is accomplished by cycling power with FS_B in a HIGH or
LOW state.
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
initializes 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 3.
The block write and block read protocol is outlined in
Table 4
while
Table 5
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
Table 3. 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'
Table 4. Block Read and Block Write Protocol
Block Write Protocol
Bit
1
2:8
9
10
11:18
19
Start
Slave address – 7 bits
Write = 0
Acknowledge from slave
Command Code – 8 bits
'00000000' stands for block operation
Acknowledge from slave
Description
Bit
1
2:8
9
10
11:18
19
Start
Slave address – 7 bits
Write = 0
Acknowledge from slave
Command Code – 8 bits
'00000000' stands for block operation
Acknowledge from slave
Block Read Protocol
Description
........................Document #: 38-07445 Rev. *D Page 3 of 16
CY28409
Table 4. Block Read and Block Write Protocol
(continued)
Block Write Protocol
Bit
20:27
28
29:36
37
38:45
46
....
....
....
....
....
....
Byte Count – 8 bits
Acknowledge from slave
Data byte 1 – 8 bits
Acknowledge from slave
Data byte 2 – 8 bits
Acknowledge from slave
......................
Data Byte (N–1) – 8 bits
Acknowledge from slave
Data Byte N – 8 bits
Acknowledge from slave
Stop
Description
Bit
20
21:27
28
29
30:37
38
39:46
47
48:55
56
....
....
....
Table 5. Byte Read and Byte Write protocol
Byte Write Protocol
Bit
1
2:8
9
10
11:18
Start
Slave address – 7 bits
Write = 0
Acknowledge from slave
Command Code – 8 bits
'100xxxxx' stands for byte operation, bits[4:0] of the
command code represents the offset of the byte to
be accessed
Acknowledge from slave
Data byte from master – 8 bits
Acknowledge from slave
Stop
Description
Bit
1
2:8
9
10
11:18
Start
Slave address – 7 bits
Write = 0
Acknowledge from slave
Command Code – 8 bits
'100xxxxx' stands for byte operation, bits[4:0] of
the command code represents the offset of the
byte to be accessed
Acknowledge from slave
Repeat start
Slave address – 7 bits
Read = 1
Acknowledge from slave
Data byte from slave – 8 bits
Acknowledge from master
Stop
Byte Read Protocol
Description
Repeat start
Slave address – 7 bits
Read = 1
Acknowledge from slave
Byte count from slave – 8 bits
Acknowledge from master
Data byte from slave – 8 bits
Acknowledge from master
Data byte from slave – 8 bits
Acknowledge from master
Data byte N from slave – 8 bits
Acknowledge from master
Stop
Block Read Protocol
Description
19
20:27
28
29
19
20
21:27
28
29
30:37
38
39
Control Registers
Byte 0:Control Register 0
Bit
7
6
@Pup
0
1
Reserved
PCIF
PCI
Reserved
Reserved
Name
Reserved, Set = 0
PCI Drive Strength Override
0 = Force All PCI and PCIF Outputs to Low Drive Strength
1 = Force All PCI and PCIF Outputs to High Drive Strength
Reserved, Set = 0
Reserved, Set = 0
Description
5
4
0
0
........................Document #: 38-07445 Rev. *D Page 4 of 16
CY28409
Byte 0:Control Register 0
(continued)
Bit
3
2
1
0
@Pup
Externally
Selected
Externally
Selected
Externally
Selected
Externally
Selected
Name
PCI_STP#
CPU_STP#
FS_B
FS_A
Description
PCI_STP# reflects the current value of the external PCI_STP# pin.
0 = PCI_STP# pin is LOW.
CPU_STP# reflects the current value of the external CPU_STP# pin.
0 = CPU_STP# pin is LOW.
FS_B reflects the value of the FS_B pin sampled on power-up.
FS_A reflects the value of the FS_A pin sampled on power-up.
Byte 1: Control Register 1
Bit
7
6
5
4
3
2
1
0
@Pup
0
1
1
1
1
1
1
1
Name
SRCT, SRCC
SRCT, SRCC
Reserved
Reserved
Reserved
CPUT2, CPUC2
CPUT1, CPUC1
CPUT0, CPUC0
Description
Allows control of SRCT/C with assertion of PCI_STP# or SW PCI_STP
0 = Free Running, 1 = Stopped with PCI_STP#
SRCT/C Output Enable; 0 = Disabled (Hi-z), 1 = Enabled
Reserved, Set = 1
Reserved, Set = 1
Reserved, Set = 1
CPUT/C2 Output Enable; 0 = Disabled (Hi-z), 1 = Enabled
CPUT/C1 Output Enable; 0 = Disabled (Hi-z), 1 = Enabled
CPUT/C0 Output Enable; 0 = Disabled (Hi-z), 1 = Enabled
Byte 2: Control Register 2
Bit
7
6
5
4
3
2
1
0
@Pup
0
0
0
0
0
0
0
0
Name
SRCT, SRCC
SRCT, SRCC
CPUT2, CPUC2
CPUT1, CPUC1
CPUT0, CPUC0
CPUT2, CPUC2
CPUT1, CPUC1
CPUT0, CPUC0
Description
SRCT/C Pwrdwn Drive Mode
0 = Driven during power-down, 1 = Three-state during power-down
SRCT/C Stop Drive Mode
0 = Driven during PCI_STP, 1 = Three-state during PCI_STP
CPUT/C2 Pwrdwn Drive Mode
0 = Driven during power-down, 1 = Three-state during power-down
CPUT/C1 Pwrdwn Drive Mode
0 = Driven during power-down, 1 = Three-state during power-down
CPUT/C0 Pwrdwn Drive Mode
0 = Driven during power-down, 1 = Three-state during power-down
CPUT/C2 stop Drive Mode
0 = Driven when stopped, 1 = Three-state when stopped
CPUT/C1 stop Drive Mode
0 = Driven when stopped, 1 = Three-state when stopped
CPUT/C0 stop Drive Mode
0 = Driven when stopped, 1 = Three-state when stopped
Byte 3: Control Register 3
Bit
7
@Pup
1
Name
SW PCI STOP
Description
SW PCI_STP Function
0= PCI_STP assert, 1= PCI_STP deassert
When this bit is set to 0, all STOPPABLE PCI, PCIF and SRC outputs will
be stopped in a synchronous manner with no short pulses.
When this bit is set to 1, all STOPPED PCI,PCIF and SRC outputs will
resume in a synchronous manner with no short pulses.
PCI6 Output Enable
0 = Disabled, 1 = Enabled
6
1
PCI6
........................Document #: 38-07445 Rev. *D Page 5 of 16
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