Cypress W210H Datasheet

W210

Spread Spectrum FTG for VIA K7 Chipset

Features

• Maximized EMI Suppression usi ng Cypress’s Spread
Spec trum te chnol ogy

• Single-chi p system frequency synthesizer for VIA K7
chipset

• One pair of different ial CPU outputs for K7 Processor

• One open-drain CPU output for VIA K7 chips et

• Six copies of PCI output

• One 48-MHz output for USB

• One 24-MHz or 48-MHz output for SIO

• T wo buffered reference outputs

• Thirteen SDRAM outputs provide support for 3 DIMMs

• Supports frequencies up to 200 MHz

2

•I

C™ interface for programming

• Power man agement control inputs

• Available in 48-pin SSOP

Key Specific ati o n s

CPU to CPU Output Skew:.... .. ................................... 175 ps

PCI to PCI Output Skew:...................... ...................... 500 ps

: .................................................................... 3.3V±5%

V

DDQ3

T able 1. Mode Input Table

Mode Pin 2

0 CPU_STOP#
1REF0

T able 2. Pin Selectable Fre quency

Input Address

CPU

(MHz)

PCI0:5

(MHz)

Spread

SpectrumFS3 FS2 FS1 FS0

1 1 1 1 133.3 33.3 ±0.5%
1 1 1 0 75 37.5 ±0.5%
1 1 0 1 100.2 33.3 ±0.5%
1 1 0 0 66.8 33.4 ±0.5%
1 0 1 1 79 39.5 OFF
1 0 1 0 110 36.7 OFF
1 0 0 1 115 38.3 OFF
1 0 0 0 120 30 OFF
0 1 1 1 133.3 33.3 OFF
0 1 1 0 83.3 27.7 OFF
0 1 0 1 100.2 33.3 OFF
0 1 0 0 66.8 33.4 OFF
0 0 1 1 124 31.0 OFF
0 0 1 0 129 32.3 OFF
0 0 0 1 138 34.5 OFF
0 0 0 0 143 35.8 OFF

Block Diagram

X1
X2

PWRDWN#

SDA TA

SCLK

SDRAMIN

I2C is a trademark of Philips Corporation.

PLL 1

I2C

Logic

PLL2

XTAL

OSC

÷2,3,4

PLL Ref Freq

I/O Pin
Control

Control

Stop

Clock

Pin Configuration

VDDQ3
REF0/(CPU_STOP#)
REF1/FS0

CPUT_CS

CPUT0
CPUC0

VDDQ3
PCI0/MODE
PCI1/FS1
PCI2
PCI3

PCI4
PCI5

VDDQ3

÷2

48MHz/FS2

24_48MHz/FS3

VDDQ3
SDRAM0:12

13

REF0/(CPU_STOP#)

Note:

1. Internal pull-up resistors should not be relied upon for setting I/O

VDDQ3

GND

X1
X2

VDDQ3

PCI0/MODE

PCI1/FS1*

GND
PCI2
PCI3
PCI4
PCI5

VDDQ3

SDRAMIN

GND
SDRAM11
SDRAM10

VDDQ3
SDRAM9
SDRAM8

GND

SDA TA

I2C

{

SCLK

pins HIGH. Pin function with parentheses determined by MODE pin
resistor strapping. Unlike other I/O pins, input FS3 has an internal
pull-down resistor.

[1]

REF1/FS0*

W210

48

GND

47

CPUT_CS

46

GND

45
44

CPUC0

43

CPUT0
VDDQ3

42
41

PWRDWN#*
SDRAM12

40

GND

39

SDRAM0

38

SDRAM1

37

VDDQ3

36

SDRAM2

35

SDRAM3

34

GND

33

SDRAM4

32

SDRAM5

31

VDDQ3

30

SDRAM6

29

SDRAM7

28

VDDQ3

27

48MHz/FS2*

26

24_48MHz/FS3^

25

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

Cypress Semiconductor Corporation

• 3901 North First Street • San Jose • CA 95134 • 408-943-2600
April 11, 2000, rev. *C

Pin Definitions

Pin Name Pin No. Pin Type Pin Description

CPUT0,
CPUC0,
CPUT_CS

PCI2:5 10, 11, 12, 13 O

PCI1/FS1 8 I/O

PCI0/MODE 7 I/O

PWRDWN# 41 I

48MHz/FS2 26 I/O

24_48MHz/
FS3

REF1/FS0 48 I/O

REF0/
CPU_STOP#

SDRAMIN 15 I

SDRAM0:12 38, 37, 35,

SCLK 24 I Clock pin for I
SDATA 23 I/O Data pi n for I
X1 4 I

X2 5 I

VDDQ3 1, 6, 14, 19,

GND 3, 9, 16, 22,

43, 44, 46 O

(open-

drain)

25 I/O

2 I/O

O
34, 32, 31,
29, 28, 21,

20, 18, 17, 40

P

27, 30, 36, 42

G

33, 39, 45, 47

CPU Clock Output 0:

for the K7 proc essor. CPUT_CS is the open-drain cl ock output for the chips et. It
has the same phase relat ionship as CPUT0.

PCI Clock Outpu ts 2 through 5:

the PWRDWN# control pin. Frequency is set by FS0:3 inputs or through serial
input interface, see Tables 2 and 6 for details. Output voltage swing is controlled
by volt age applied to VDDQ3.

Fixed PCI Clo ck Output/Frequency Select 1:

FS0:3 inputs or through serial input interface. This output is controlled by the
PWRDWN# input. This pin also serves as a power-on strap opt ion to determine
device operating frequency as describe d in Table 2.

Fixed PCI Cloc k Output/Mode:

or through serial inp u t i nterface, see Tables 2 and 6. This output is controlled by
the PWRDWN# input. This pin also serves as a power -on strap option to determine
the function of pin 2, see Table 1 for details.

PWRDWN# Input :

mode when held LOW. In power-down mode,CPUC0 will be three-stated and all
the other output clocks will be driven LOW.

48-MHz Output/Fr equency Se lec t 2:

standard PC systems, this output can be used as the reference for the Uni versal
Serial Bus host control ler. This pin also serves as a power-on strap option to
determine device operating frequency as desc ribe d in Table 2.

24_48-MHz Outpu t/Frequency Sel ect 3:

be used as the clock input f or a Super I/O chip . The output frequency is controlled
by Configur ation Byte 3 bit[6]. The defaul t out put frequency is 24 MHz. This pin
also serves as a power -on strap option to determine device operating frequency
as described in Table 2.

Reference Cloc k Output 1/Frequency Sel ect 2:

This pin also serves as a power-on strap option to dete rmine device operating
frequency as described in Table 2. Upon power-up, FS0 input will be latched, which
will set clock frequencies as described in Table 2.

Reference Cloc k Output 0 or CPU_STOP# Input Pin:

by the MODE pin. When CPU_ST OP# inp ut is asse rted LOW, it will drive CPUT0
and CPUT_CS to l ogic 0, and it will three -state CPUC0. When this pin i s configured
as an output, this pin becom es a 3.3V 14. 318-MHz output clock.

Buffered Input Pin:

(SDRAM0:12).

Buffered Outputs:

provided at the SDRAMIN input. The swing is set by VDDQ3, and they are deac­tivated when PWRDWN# input is set LOW.

2

C circuitry.

2

C circuitry .

Crystal Connection or Ext ernal Ref erence Frequenc y Input:

functions . It can be used as an external 14.318-MHz crystal con nection or as an
external reference frequency input.

Crystal Connection:

using an external reference, this pin must be left unconnected.

Power Connection:

PCI outputs, ref erence outp uts, 48-MHz ou tput, and 24_4 8-MHz ou tpu t. Connect
to 3.3V supp ly.

Ground Connections:

plane.

CPUT0 and CPUC0 are the differ ential CPU cl oc k output s

These four PCI clock outputs are controlled by

As an output, frequency is set by the F S0:3 inputs

LVTTL-compatibl e inpu t that place s t he de vi ce in po we r-do wn

48 MHz is provi ded in normal operat ion. In

The signal pr ovide d t o this input pin i s buf f ere d to 13 outp uts

These thirteen d edicat ed outpu ts prov ide cop ies of t he sig nal

An input connection for an external 14.318-MHz crystal. If

Power supply for core logic, PLL circuitry, SDRAM outputs,

Connect all ground pins to the common system ground

W210

As an output, frequency is set by

In standard PC systems, th is output can

3.3V 14.318-MHz output clock.

Function is determined

This pin has dual

2

W210

Overview

The W210 was developed as a single-chip device to meet the
clockin g needs of VIA K7 c ore logic chi p sets. I n addition t o the
typical ou tputs provided by a standard FTG, the W210 adds a
thirteenth output buff er, supporting SDRAM DIMM modules in
conjunction with the chipset.

Cypress’s proprietary spread spectrum frequency synthesis
technique is a feature of the CPU and PCI outputs. When en­abled, th is feat ure reduces the peak EMI measurement s of not
only the output signals and their harmonics, but also of any
other clock signals that are properly synchr onized to them.

Functional Description

I/O Pin Operation

Pins 7, 8, 25, 26, and 48 are dual-purpose l/O pins. Upon
power-up these pins act as logic inputs, allowing the determi­nation of assigned device functions. A short time after power­up, the logic state of each pin is latched and the pins becom e
clock outputs. This feature reduces device pin count by com­bining cloc k outputs with input select pins .

An external 10-kΩ “strapping” resistor is connected between
the l/O pin and ground or V
latch to “0,” connection to V
Figure 2 show two suggested methods for strapping resistor
connections.

. Connection to ground sets a

DD

sets a latch to “1.” Fig ure 1 an d

DD

Upon W210 power-up, the first 2 ms of operation is used for
input logic selection. During this period, the five I/O pin s (7, 8,
25, 26, 48) are three-stated, allowing the output strapping re­sistor on the l/O pins to pull the pins and their associated ca­pacitiv e clock load to either a logic HIGH or LOW state. At the
end of the 2-ms period, the established logic “0” or “1” condi­tion of the l/O pin is latched. Next the output buffer is enabl ed
converting t he l/O pins into operating clock outputs. The 2-ms
timer starts w hen V
be reset by turning V

reaches 2.0V. The input bits can only

DD

off and then back on again.

DD

It should be noted that the strapping resistors have no signifi­cant effect on clock output signal integrity. The drive imped­ance of clock outputs is <40Ω (nominal), which is minimally
affected by the 10-kΩ strap to ground or V
ries termination resistor, the output strapping resistor should

. As with the se-

DD

be placed as close to the l/O pin as possible in order to keep
the interconnecting trace short. The trace from the resistor to
ground or V

should be ke pt less t han tw o i nches i n lengt h t o

DD

prevent system noise coupling during input l ogic sampling.
When the clock outputs are enabled following the 2-ms input

period, the specified output frequency is delivered on the pin,
assuming that V
full value , output frequency initi ally ma y be belo w target b ut will
increase to target once V
case, a shor t output clock cycle may be produced from the

has stabilized. If VDD has not yet reached

DD

voltage has stabilized. In either

DD

CPU clock outputs when the outputs are enabled.

V

DD

Output Stra pp i ng Resi st or

W210

Power-on
Reset
Timer

W210

Power-on
Reset
Timer

10 k

Output Three -state

Output
Buffer

Hold
Output
Low

QD

Data

Latch

(Load Option 1)

(Load Option 0)

10 k

Ω

Ω

Figure 1. Input Logic Selection Through Resistor Load Option

Jumper Options

V

DD

10 k

Ω

Output
Buffer

Output Three -state

Hold
Output
Low

QD

Data

Latch

Resistor Value R

Series Termination Resistor

R

Output Stra pp i ng Resi st or

Series Termination Resistor

R

Clock Load

Clock Load

Figure 2. Input Logic Selection Through Jumper Option

3

W210

Spread Spectrum Frequency Tim ing G enera to r

The device generates a clock that is frequency modulated in
order to increase the bandwidth that it occu pies. By increas ing
the bandwidth of the fundamental and its harmonics, the am­plitudes of the radiated electromagnetic emissions are re­duced. This effect is depicted in Figure 3.

As shown in Figure 3, a harmonic of a modulated clock has a
much low er amplitu de than that of an un modulated si gnal. The
reduction in amplitude is dependent on the harmonic number
and the frequency deviation or spread. The equation for the
reduction is:

dB = 6.5 + 9*log

(P) + 9*log10(F)

10

Amplitude (dB)

5 dB/d iv

SSFTG Ty p ic al Clock

Where P is the percenta ge of de vi ation and F is the frequen cy
in MHz where the reduction is measured.

The output clock is modulated with a waveform depicted in
Figure 4. This waveform, as discussed in “Spread Spectrum
Clock Generation f or the Reducti on of Radiated Emissio ns” by
Bush, Fessler, and Hardin produces the maximum reduction
in the amplitude of radiated electromagnetic emissions. The
deviati on select ed for this chi p is speci fied in Table 6. Figure 4
details the Cypress spr eading pat tern. Cypres s does off er op­tions with more spread and greater EMI reduction. Contact
your local Sales representative for details on these devices.

Spread Spectrum clocking is activated or deactivated by se­lecting the appropriate v al ues fo r bits 1–0 in data byte 0 of the

2

I

C data stream. Refer to Table 6 for more details.

-SS %

Frequency S pan (MHz)

+SS%

Figure 3. Clock Harmonic with and without SSCG Modulation Frequency Domain Representation

MAX (0%)

10%

20%

30%

40%

50%

60%

70%

80%

FREQUENCY

MIN (–0.5%)

90%

100%

10%

20%

30%

40%

50%

60%

70%

80%

90%

Figure 4. Typica l Modulation Profile

100%

4

W210

Serial Data Interface

The W210 features a two-pin, serial data interface that can be
used to configure internal register settings that control partic­ular de vice funct ions. Upon po wer-up , the W210 i nitiali zes wit h
default register settings, therefore the use of this serial data
interface is optional. The serial interface is write-only (to the
clock chi p) and i s the dedi cated f unc tion of de v ice pi ns SDA TA
and SCLOCK. In motherboard applications, SDATA and
SCLOCK are typically driven by two logic outputs of the

T able 3. Serial Data Interface Control Functions Summary

Control Function Description Common Application

Clock Output Disable Any individual clock output(s) can be disabled. Dis-

CPU Clock Frequency
Selection

Spread Spectrum
Enabling

Output Three-state Puts clock output into a high imped ance state. Production PCB testing.
(Reserved) Reserved functio n for future device r evision or pro-

abled outputs ar e actively held LOW.

Provides CPU/PCI frequency selections through
software. Frequency is changed in a smooth and
controlled fashion.

Enables or disables spread spectrum clocking. For EMI reduction.

duc tion devi c e testi n g.

chipset. 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. Tabl e 3 summarizes the control functions of
the serial data interface.

Operation

Data is written to the W210 in elev en bytes of eight bits each.
Bytes are written in the order shown in Table 4.

Unused outputs are di sabled to reduce EMI
and system power. Examples are clock out­puts to unused PCI slots.

For alternate microprocessors and power
management options . Smooth freque ncy tran­sition allows CPU frequency change under
normal system operati on.

No user applicat ion. Regist er bit must be wri t­ten as 0.

Table 4. Byte Writing Sequence

Byte Sequence Byte Name Bit Sequence Byte Description

1 Slave Address 11010010 Commands the W210 to accept the bits in Data Bytes 0–6 for internal

register configuration. Since other devices may exist on the same com ­mon serial data b us , it is neces sary to ha v e a speci fic s lav e address for
each potential receiver. The slave receiver address for the W210 is

11010010. Register sett ing will not be made if t he Slav e Address is not
correct (or is for an alternate slave recei ver).

2 Command

Code

3 Byte Count Don’t Care Unused by the W210, therefore bit values are ignored (“Don’t C a re”).

4 Data Byte 0 Refer to Ta ble 5 The data bits in Dat a Bytes 0 –7 set internal W 210 regi sters that co ntrol
5 Data Byte 1
6 Data Byte 2
7 Data Byte 3
8 Data Byte 4

9 Data Byte 5
10 Data Byte 6
11 Data Byte 7

Don’t Care Unused by the W210, therefore bit values are ignored (“Don’t Care”).

This byte m ust be inclu ded in the dat a write sequence to maintain pro per
byte allocatio n. The Command Code Byte is part of the standard serial
communication protocol and may be used when writing to another ad­dressed slave receiver on the serial data bus.

This byte m ust be inclu ded in the dat a write sequence to maintain pro per
byte alloc ati on. The Byte Count Byte is part of the standard serial com­munication pr otocol and may be used wh en writing to another address ed
slave receiver on the serial data bus.

device operation. The data bits are only accept ed when the Address
Byte bit sequence is 11010010, as noted above. F or description of bit
control functions, refer to Table 5, Data Byte Serial Configuration Map.

5