CY28354-400
210 MHz 24 Output Buffer for 4-DDR DIMMS for VIA Chipsets
Support
Features
• Supports VIA PRO 266, KT266 and P4x266
• Dual 1- to 12-output buffer/driver
• Supports up to four DDR DIMMs
• Low-skew outputs (< 75 ps)
• Supports 266-MHz, 333-MHz and 400-MHz DDR SDRAM
• SMBus Read and Write support
• Space-saving 48-pin SSOP package
Functional Description
The CY28354-400 is a 2.5V buffer designed to distribute
high-speed clocks in PC applications. The part has 24 outputs
to support four unbuffered DDR DIMMS. The CY28354-400
can be used in conjunction with CY28326 similar clock synthe-
sizer for the PTT880 and KTT880 chipsets.
The CY28354-400 also includes an SMBus interface which
can enable or disable each output clock. On power-up, all
output clocks are enabled.
Block Diagram
BUF_INA
FB_OUTA
DDRAT0
DDRAC0
DDRAT1
DDRAC1
DDRAT2
DDRAC2
DDRAT3
DDRAC3
DDRAT4
DDRAC4
DDRAT5
DDRAC5
DDRBT0
DDRBC0
DDRBT1
DDRBC1
DDRBT2
DDRBC2
DDRBT3
DDRBC3
DDRBT4
DDRBC4
DDRBT5
DDRBC5
FB_OUTB
Pin Configuration
SSOP
Top View
VDD2.5
GND
FB_OUTB
BUFF_INB
DDRBT0
DDRBC0
DDRBT1
DDRBC1
GND
VDD2.5
DDRAT0
DDRAC0
DDRAT1
DDRAC1
GND
VDD2.5
FB_OUTA
BUF_INA
DDRAT2
DDRAC2
DDRAT3
DDRAC3
VDD2.5
GND
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
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
ADDR_SEL
SDATA
SMBus
Decoding
SCLOCK
I2C_CS
VDD2.5
GND
ADDR_SEL
I2C_CS
DDRBT2
DDRBC2
DDRBT3
DDRBC3
GND
VDD2.5
DDRAT4
DDRAC4
DDRAT5
DDRAC5
GND
VDD2.5
DDRBT4
DDRBC4
DDRBT5
DDRBC5
VDD2.5
GND
SDATA
SCLK
BUFF_INB
.......................... Document #: 38-07615 Rev. *B Page 1 of 8
400 West Cesar Chavez, Austin, TX 78701
1+(512) 416-8500
1+(512) 416-9669
www.silabs.com
CY28354-400
Pin Description
Pin
11, 13, 19, 21, 38, 36,
5, 7, 44, 42, 32, 30
12, 14, 20, 22, 37, 35,
6, 8, 43, 41, 31, 29
18,
4
17,
3
45
46
25
26
Name
DDRA[0:5]T
DDRB[0:5]T
PWR
VDD2.5
I/O
O
O
I
PD
O
I
PD
I
PD
I
PU
I/O
PU
Description
Clock outputs.
These outputs provide copies of BUF_INA and
BUF_INB, respectively.
Clock outputs.
These outputs provide complementary copies of
BUF_INA and BUF_INB, respectively.
Reference input from chipset.
2.5V input. Internal pull-down
Feedback clock for chipset.
CS for I2C allows for multiple devices to be connected with
the same I2C address.
Internal pull-down. See
Table 1.
Selects I2C Address D2/DC.
Internal Pull-down
SMBus clock input.
Internal Pull-up
SMBus data input.
Internal Pull-up
2.5V voltage supply
Ground
DDRA[0:5]C VDD2.5
DDRB[0:5]C
BUF_INA,
BUF_INB
FB_OUTA
FB_OUTB
I2C_CS
ADDR_SEL
SCLK
SDATA
VDD2.5
VDD2.5
VDD2.5
VDD2.5
VDD2.5
VDD2.5
1, 10, 16, 23, 28, 33, 39, 48 VDD2.5
2, 9, 15, 24, 27, 34, 40, 47
GND
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, etc., 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 can also be used during system
operation for power management functions.
Table 1. Command Code Definition
Bit
7
(6:5)
(4:0)
0 = Block Read or Block Write operation
1 = Byte Read or Byte Write operation
01 to address chip when I2C_CS = 0
10 to address chip when I2C_CS = 1
Data Protocol
The clock driver serial protocol accepts Byte Write, Byte Read,
Block Write, and Block Read operation 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 individual indexed bytes. The
offset of the indexed byte is encoded in the command code,
as described in
Table 1.
The Block Write and Block Read
protocol is outlined in
Table 2.The
slave receiver address is
D2/DC depending on the state of the ADDRSEL pin.
Description
Byte offset for Byte Read or Byte Write operation. For Block Read or Block Write operations, these bits should
be '00000'
..........................Document #: 38-07615 Rev. *B Page 2 of 8
CY28354-400
Table 2. Block Read and Block Write Protocol
Block Write Protocol
Bit
1
2:8
9
10
11:18
19
20:27
28
29:36
37
38:45
46
....
....
....
....
Start
Slave address – 7 bits
Write = 0
Acknowledge from slave
Command Code – 8 bits
'00000000' stands for block operation
Acknowledge from slave
Byte Count from master – 8 bits
Acknowledge from slave
Data byte 0 from master – 8 bits
Acknowledge from slave
Data byte 1 from master – 8 bits
Acknowledge from slave
Data bytes from master/Acknowledge
Data Byte N – 8 bits
Acknowledge from slave
Stop
Description
Bit
1
2:8
9
10
11:18
19
20
21:27
28
29
30:37
38
39:46
47
48:55
56
....
....
....
....
Start
Slave address – 7 bits
Write = 0
Acknowledge from slave
Command Code – 8 bits
'00000000' stands for block operation
Acknowledge from slave
Repeat start
Slave address – 7 bits
Read = 1
Acknowledge from slave
Byte count from slave – 8 bits
Acknowledge
Data byte 0 from slave – 8 bits
Acknowledge
Data byte 1 from slave – 8 bits
Acknowledge
Data bytes from slave/Acknowledge
Data byte N from slave – 8 bits
Not Acknowledge
Stop
Block Read Protocol
Description
Serial Configuration Map
• The Serial bits will be read by the clock driver in the following
order.
Byte 0 – Bits 7, 6, 5, 4, 3, 2, 1, 0
Byte 1 – Bits 7, 6, 5, 4, 3, 2, 1, 0
Byte N – Bits 7, 6, 5, 4, 3, 2, 1, 0
• Reserved and unused bits should be programmed to “0”
• SMBus Address for the CY28354 is as follows.
A6
SEL ADDR = 1
SEL ADDR = 0
1
1
A5
1
1
A4
0
0
A3
1
1
A2
0
1
A1
0
1
A0 R/W
1
0
—
—
..........................Document #: 38-07615 Rev. *B Page 3 of 8
CY28354-400
Byte 22: Outputs Active/Inactive Register (1 = Active, 0 = Inactive), Default (Hi-z) = Active
Bit
Bit 7
Bit 6
@Pup
0
0
Pin #
Input Threshold Control
00: Normal (1.25V)
01: 1.20V
10: 1.15V
11: 1.10V
17
3
30,
29
32,
31
42,
41
44,
43
FBOUTA Control, 0 = Enable, 1 = Disable
FBOUTB Control, 0 = Enable, 1 = Disable
DDRBT5,
DDRBC5
DDRBT4,
DDRBC4
DDRBT3,
DDRBC3
DDRBT2,
DDRBC2
Description
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0
0
1
1
1
1
Byte 23: Outputs Active/Inactive Register (1 = Active, 0 = Inactive), Default = Active
Bit
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
@Pup
1
1
1
1
1
1
1
1
7,
8
5,
6
36,
35
38,
37
21,
22
19,
20
13,
14
11,
12
Pin #
DDRBT1,
DDRBC1
DDRBT0,
DDRBC0
DDRAT5,
DDRAC5
DDRAT4,
DDRAC4
DDRAT3,
DDRAC3
DDRAT2,
DDRAC2
DDRAT1,
DDRAC1
DDRAT0,
DDRAC0
Description
..........................Document #: 38-07615 Rev. *B Page 4 of 8
CY28354-400
Absolute Maximum Conditions
[1]
Parameter
V
DD
V
in
V
out
T
s
T
a
Ø
JC
Ø
JA
ESD
h
Description
Supply Voltage to Ground Potential
DC Input Voltage (except BUFF_IN)
Output Voltage
Temperature, Storage
Temperature, Operating Ambient
Dissipation, Junction to Case (Mil-Spec 883E Method 1012.1)
Dissipation, Junction to Ambient (JEDEC (JESD 51)
ESD Protection (Human Body Model)
–
Min.
–0.5
–0.3
1.1
–65
0
36.39
77.99
2000
Max.
4.6
V
DD
+0.3
V
DD
–0.4
+150
85
Unit
V
V
V
°C
°C
°C/W
°C/W
V
DC Electrical Specifications
Parameter
V
DD2.5
C
OUT
C
IN
Supply Voltage
Output Capacitance
Input Capacitance
Description
Min.
2.3
–
–
Typ.
–
6
5
Max.
2.7
–
–
Unit
V
pF
pF
AC Electrical Specifications
Parameter
V
IL
V
IH
I
OH
I
OL
V
OL
V
OH
I
DD
I
DD
I
DDPD
V
OUT
V
OC
IN
DC
Description
Input LOW Voltage
Input HIGH Voltage
Output HIGH Current
Output LOW Current
Output LOW
Voltage
[2]
Output HIGH Voltage
[2]
Supply Current
[2]
Supply Current
Supply Current
Output Voltage Swing
Output Crossing Voltage
Input Clock Duty Cycle
V
DD
= 2.375V, V
OUT
= 1V
V
DD
= 2.375V, V
OUT
= 1.2V
I
OL
= 12 mA, V
DD
= 2.375V
I
OH
= –12 mA, V
DD
= 2.375V
Unloaded outputs, 133 MHz
Loaded outputs, 133 MHz
All outputs off
See Test Circuity. See
Figure 1
Conditions
For all pins except SMBus
Min.
0.3
1.7
–
–
–
1.7
–
–
–
0.7
V
DD
/2–0.3
40
Typ.
–
–
–
–
–
–
–
–
–
–
V
DD
/2
–
Max.
0.7
V
DD
+ 0.3
–12
12
0.5
–
400
500
2
V
DD
+ 0.6
V
DD
/2+0.3
60
Unit
V
V
mA
mA
V
V
mA
mA
mA
V
V
%
Switching Characteristics
[3]
Parameter
–
–
t
3d
t
4d
t
5
t
6
Name
Operating Frequency
Duty Cycle
[2, 4]
= t
2
t
1
DDR Rising Edge Rate
[2]
DDR Falling Edge Rate
[2]
Measured differentially at V
CROSS
Measured single ended at 20% to 80% of V
DIF
Measured single ended at 80% to 20% of V
DIF
Test Conditions
Min.
60
IN
DC
–2%
1.0
1.0
–
–
–
2.0
2.0
–
–
Typ.
Max.
210
IN
DC
+2%
5.0
5.0
75
6
Unit
MHz
%
V/ns
V/ns
ps
ns
Output to Output Skew for All outputs equally loaded.
DDR
[2]
See
Figure 1.
Input to Output Propagation At output load of 15 pFn
delay
Notes:
1. Multiple Supplies: The voltage on any input or I/O pin cannot exceed the power pin during power-up. Power supply sequencing is NOT required.
2. Parameter is guaranteed by design and characterization. Not 100% tested in production.
3. All parameters specified with loaded outputs.
4. Duty cycle of input clock is 50%. Rising and falling edge rate is greater than 1 V/ns.
..........................Document #: 38-07615 Rev. *B Page 5 of 8
