Cypress Clock CY25566 User Manual

CY25566  
Spread Spectrum Clock Generator  
• Center spread modulation  
• Low cycle-to cycle jitter  
• 16-pin SOIC package  
Features  
• 25- to 200-MHz operating frequency range  
• Wide range of spread selections (9)  
• Accepts clock or crystal inputs  
• Provides four clocks  
Applications  
• High-resolution VGA controllers  
• LCD panels and monitors  
• Printers and MFPs  
— SSCLK1a  
— SSCLK1b  
— SSCLK2  
Benefits  
— REFOUT  
• Peak EMI reduction by 8 to 16 dB  
• Fast time to market  
Cost reduction  
• Low-power dissipation  
3.3V = 70 mW (typical @ 40 MHz, no load)  
Pin Configuration  
Block Diagram  
REFOFF  
2
300K  
XIN/CLKIN  
REFOFF  
REFOUT  
VDD  
1
2
3
4
5
6
7
8
16 XOUT  
15 SSCLK2  
14 VSS  
13 S0  
3
REFOUT  
REFERENCE  
DIVIDER  
Xin/  
CLK  
1
Loop  
Filter  
PD  
CP  
VSS  
12 S1  
Xout  
16  
MODULATION  
CONTROL  
FEEDBACK  
DIVIDER  
vco  
S2  
11 VSS  
10 SSCC  
S3  
SSCLK1a  
9
SSCLK1b  
VDD  
VSS  
4
INPUT  
DECODER  
LOGIC  
DIVIDER  
&
MUX  
8 SSCLK1a  
9 SSCLK1b  
15 SSCLK2  
5
VDD  
VDD  
20 K  
20 K  
11  
14  
VSS  
VSS  
/2  
RANGE  
CONTROL  
20 K  
VSS  
20 K  
VSS  
6
13  
12  
S1 S0  
7
10  
SSCC  
S2 S3  
Cypress Semiconductor Corporation  
Document #: 38-07429 Rev. *B  
3901 North First Street  
San Jose  
CA 95134  
408-943-2600  
Revised October 26, 2005  
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CY25566  
SSCLK1a/b  
Control Logic Structures  
SSCLK1a and SSCLK1b are spread spectrum clock outputs  
used for the purpose of reducing EMI in digital systems.  
SSCLK1a and SSCLK1b can be connected in several different  
ways to provide flexibility in application designs. Each clock  
can drive separate nets with a capacitative load up to 15 pF  
each or connected together to provide drive to a single net with  
a capacitative load as high as 33 pF. When both clocks are  
connected together, the CY25566 is capable of driving 3.3V  
CMOS-compatible clocks to frequencies as high as 200 MHz.  
If one clock output is not connected to a load, negligible EMI  
will be generated at the unused pin because there is no current  
being driven. The frequency and bandwidth of SSCLK1a and  
SSCLK1b is programmed by the logic states presented to S2  
and S3. The frequency multiplication at SSCLK1a and  
SSCLK1b is either 1X or 2X, controlled by S2 and S3. The  
modulated output clock SSCLK1 is provided at pins 8 and 9  
with each pin having separate but identical drivers. Refer to  
Figure 1 below.  
The CY25566 has six input control pins for programming VCO  
range, BW %, Mod ON/OFF and REFOUT ON/OFF. These  
programmable control pins are described below.  
REFOFF  
The output clock REFOUT can be enabled or disabled by  
controlling the state of REFOFF. When REFOFF is at a logic  
low(0) state, REFOUT is enabled and the reference clock  
frequency is present at pin 3. When REFOFF is at a logic high  
state (1), REFOUT is disabled and is set to a logic low state  
on pin 3. REFOFF has a 400-KW internal pull-up resistor to  
V
.
DD  
S0 and S1 (Tri-level Inputs)  
S0 and S1 are used to program the frequency range and  
bandwidth of the modulated output clocks SSCLK1a/b and  
SSCLK2. S0 and S1 of the CY25566 are designed to sense  
three different analog levels. With this tri-level structure, the  
CY25566 is able to detect 9 different logic states. Refer to  
tables 5, 6 and 7 for the results of each of these 9 states. The  
level of each state is defined as follows:  
9
C Y 2 5 5 6 6  
8
Logic State “0” is a voltage that is between 0 and 0.15 × V V.  
3 3 p f .  
DD  
Logic State “M” is a voltage between 0.4 × V and 0.6 × V V.  
DD  
DD  
Logic State “1” is a voltage between 0.85 × V and V  
.
DD  
DD  
Figure 2 illustrates how to program tri-level logic.  
9
C Y 2 5 5 6 6  
S2 and S3  
1 5 p f .  
S2 and S3 are used to program the CY25566 into different  
frequency ranges and multipliers. The CY25566 operates over  
a frequency range of 25 to 200 MHz and a 1X or 2X multipli-  
cation of the reference frequency. S2 and S3 are binary logic  
8
1 5 p f .  
Figure 1. SSCLK1a/b Driver Configurations  
SSCLK2  
inputs and each has a 400 K W pull-up resistor to V . See  
DD  
Table 1, Table 2, and Table 3 for programming details.  
SSCC  
SCLK2 is a Spread Spectrum Clock with a frequency half that  
of the SSCLK1a clock frequency. When SSCLK1a is  
programmed to provide a 2.5% modulated clock at 1X times  
the reference clock, 40 MHz for example, the frequency of  
SSCLK2 will be 20 MHz with a BW of 2.5%. Note that by  
programming the frequency of SSCLK1a to 2X, the frequency  
of SSCLK2 will be 1X times the reference clock frequency.  
SSCC is an input control pin that enables or disables SSCG  
modulation of the output clock at SSCLK1a/b and SSCLK2.  
Disabling modulation is a method of comparing radiated EMI  
in a product with SSCG turned on or off.  
The CY25566 can be used as a conventional low jitter multiple  
output clock when SSCC is set to low (0). SSCC has a 400-KW  
internal pull-up resistor. Logic high (1) = Modulation ON, logic  
low (0) = Modulation OFF. Default is modulation ON.  
VDD  
VDD  
CY25566  
CY25566  
CY25566  
S0  
S0  
S0  
S1  
S0 = "M" (N/C)  
13  
12  
13  
13  
12  
10  
S0 = "1"  
S1 = "0" (GND)  
SSCC = "1"  
S0 = "1"  
S1  
S1  
S1 = "0" (GND)  
SSCC = "1"  
S1 = "1"  
12  
10  
VDD  
VDD  
10  
SSCC = "1"  
Figure 2.  
Document #: 38-07429 Rev. *B  
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CY25566  
Modulation Rate  
Spread Spectrum clock generators utilize frequency  
modulation (FM) to distribute energy over a specific band of  
frequencies. The maximum frequency of the clock (Fmax) and  
minimum frequency of the clock (Fmin) determine this band of  
frequencies. The time required to transition from Fmin to Fmax  
and back to Fmin is the period of the Modulation Rate, Tmod.  
Modulation Rates of SSCG clocks are generally referred to in  
terms of frequency or Fmod = 1/Tmod.  
The CY25566 has three frequency groups to select from. Each  
combination of frequency and bandwidth can be selected by  
programming the input control lines, S0–S3, to the proper logic  
state.  
Group 1 is the 1X low-frequency range and operates from 25  
to 100 MHz.  
Group 2 is the 1X high-frequency range and operates from 50  
to 200 MHz.  
The input clock frequency, Fin, and the internal divider count,  
Cdiv, determine the Modulation Rate. The CY25566 utilizes  
two different modulation rate dividers, depending on the range  
selected on S2 and S3 digital control inputs. Refer to the  
example below.  
Group 3 is the 2X low frequency range and operates from 25  
to 50 MHz and 50 to 100 MHz output.  
S3, S2  
0,0  
CDiv  
1166  
1166  
2332  
N/A  
Output Frequency  
1X  
2X  
0,1  
1,0  
1X  
1,1  
N/A  
Example:  
Device = CY25566  
Fin = 65 MHz  
Range = S3 = 0, S2 = 1, S0 = 0  
Then: modulation rate = Fmod = 65 MHz/1166 = 55.7 kHz  
Spectrum Analyzer  
Modulation Profile  
Figure 3. SSCG Clock, CY25566, 65 MHz  
Document #: 38-07429 Rev. *B  
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CY25566  
Table 1. Frequency and Bandwidth Selection Chart (Group 1)(Low Frequency (1x) Selection Chart)  
25–50 MHz (Low Range)  
XIN/CLK  
(MHz)  
S1 = M  
S0 = M  
S1 = M  
S0 = 0  
S1 = 1  
S0 = 0  
S1 = 0  
S0 = 0  
S1 = 0  
S0 = M  
25–35  
35–40  
40–45  
45–50  
4.3  
3.9  
3.7  
3.4  
3.8  
3.5  
3.3  
3.1  
3.4  
3.1  
2.8  
2.6  
2.9  
2.5  
2.4  
2.2  
2.8  
2.4  
2.3  
2.1  
S3  
0
S2  
0
50–100 MHz (High Range)  
XIN/CLK  
(MHz)  
S1 = 1  
S0 = M  
S1 = 0  
S0 = 1  
S1 = 1  
S0 = 1  
S1 = M  
S0 = 1  
50–60  
60–70  
70–80  
80–100  
2.9  
2.8  
2.6  
2.4  
2.1  
2.0  
1.8  
1.7  
1.5  
1.2  
1.4  
1.1  
S3  
0
S2  
0
1.3  
1.1  
1.2  
1.0  
Table 2. Frequency and Bandwidth Selection Chart (Group 2)(High Frequency (1x) Selection Chart)  
50–100 MHz (Low Range)  
XIN/CLK  
(MHz)  
S1 = M  
S0 = M  
S1 = M  
S0 =0  
S1 = 1  
S0 = 0  
S1 = 0  
S0 = 0  
S1 = 0  
S0 = M  
50–60  
60–70  
70–80  
80–100  
4.2  
4.0  
3.8  
3.5  
3.8  
3.6  
3.4  
3.1  
3.2  
3.1  
2.9  
2.7  
2.8  
2.6  
2.5  
2.2  
2.7  
2.5  
2.4  
2.1  
S3  
1
S2  
0
100–200 MHz (High Range)  
XIN/CLK  
(MHz)  
S1 = 1  
S0 = M  
S1 = 0  
S0 = 1  
S1 = 1  
S0 = 1  
S1 = M  
S0 = 1  
100–120  
120–130  
130–140  
140–150  
150–160  
160–170  
170–180  
180–190  
190–200  
3.0  
2.7  
2.6  
2.6  
2.5  
2.4  
2.4  
2.3  
2.3  
2.4  
2.1  
2.0  
2.0  
1.8  
1.8  
1.8  
1.7  
1.6  
1.6  
1.3  
1.4  
1.1  
1.3  
1.1  
1.3  
1.1  
1.2  
1.0  
S3  
1
S2  
0
1.2  
1.0  
1.2  
1.0  
1.1  
0.9  
1.1  
0.9  
Table 3. Frequency and Bandwidth Selection Chart (Group 3)(Low Frequency (2x) Selection Chart)  
25–50 MHz (Low Range, 2X)  
XIN/CLK  
(MHz)  
SSCLK1  
(MHz)  
S1 = M  
S0 = M  
S1 = M  
S0 = 0  
S1 = 1  
S0 = 0  
S1 = 0 S1 = 0  
S0 = 0 S0 = M  
25–35  
35–40  
40–45  
45–50  
50-70  
70-80  
80-90  
90-100  
4.0  
3.8  
3.5  
3.3  
3.5  
3.3  
3.1  
2.9  
3.0  
2.9  
2.7  
2.5  
2.6  
2.4  
2.2  
2.1  
2.5  
2.3  
2.1  
2.0  
S3  
0
S2  
1
Document #: 38-07429 Rev. *B  
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CY25566  
Application Schematic  
In this example, the CY25566 is being driven by a 75-MHz  
reference clock.  
V
= 3.30 VDC.  
DD  
SSCLK1a = 75 MHz @ 2.5% center spread modulation.  
SSCLK1b = 75 MHz @ 2.5% center spread modulation.  
SSCLK 2 = 37.5 MHz @ 2.5% center spread modulation.  
REFOUT = 37.5 MHz non-modulated clock.  
S0 = 0 and S1 = 0 are programmed to select a BW of 2.5%.  
(Refer to Table 1 and 2.)  
S2 = 0 and S3 = 1 are programmed to select the Group 2  
range.  
VDD  
0.1 uF  
4
75 MHz Clock source  
1
VDD  
XIN/CLKIN  
3
REFOUT  
SSCLK2  
REFOUT  
SSCLK2  
SSCLK1a  
SSCLK1b  
16  
XOUT  
15  
8
CY25566  
2
REFOFF  
VDD  
SSCLK1a  
SSCLK1b  
10  
SSCC  
7
S3  
S2  
S1  
6
9
12  
13  
S0  
VSS  
VSS  
11  
VSS  
14  
5
Figure 4. Application Schematic  
Document #: 38-07429 Rev. *B  
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CY25566  
Absolute Maximum Ratings[1, 2]  
Supply Voltage (V : .......................................................+6V  
DD  
Operating Temperature:......................................0°C to 70°C  
Storage Temperature ..................................65°C to +150°C  
Table 4. DC Electrical Characteristics V = 3.3V, Temp. = 25°C, unless otherwise noted  
DD  
Parameter  
Description  
Power Supply Range  
Input High Voltage  
Input Middle Voltage  
Input Low Voltage  
Conditions  
Min.  
Typ.  
Max.  
Unit  
V
V
±10%  
2.97  
3.3  
3.63  
DD  
V
V
V
V
V
V
V
S0 and S1 only.  
S0 and S1 only.  
S0 and S1 only.  
0.85V  
0.40V  
0.0  
V
V
DD  
V
INH  
INM  
INL  
DD  
DD  
DD  
0.50V  
0.0  
0.60V  
0.15V  
V
V
DD  
DD  
DD  
Output High Voltage  
Output High Voltage  
Output Low Voltage  
Output Low Voltage  
Input Capacitance  
I
I
I
I
= 6 ma, SSCLKa  
= 20 ma, SSCLKb  
= 6 ma, SSCLKa  
= 20 ma, SSCLKb  
2.4  
V
OH1  
OH2  
OL1  
OL2  
OH  
OH  
OH  
OH  
2.0  
V
0.4  
1.2  
5
V
V
C
C
C
Xin/CLK (Pin 1)  
3
6
3
4
8
pF  
pF  
pF  
mA  
mA  
mA  
mA  
in1  
in2  
Input Capacitance  
Xout (Pin 8)  
10  
5
Input Capacitance  
Power Supply Current  
Power Supply Current  
Power Supply Current  
Power Supply Current  
All input pins except 1.  
FIN = 40 MHz,15 pF@all outputs  
FIN = 40 MHz, No Load  
FIN = 165 MHz,15 pF@all outputs  
FIN = 165 MHz, No Load  
4
in2  
I
I
I
I
27  
21  
68  
48  
32  
28  
80  
60  
DD1  
DD1  
DD2  
DD2  
Table 5. Electrical Timing Characteristics V = 3.3V, T = 25°C and C = 15 pF, unless otherwise noted. Rise/Fall @ 0.4–2.4V,  
DD  
L
Parameter  
Description  
Conditions  
Min.  
25  
Typ.  
Max  
200  
1.6  
1.6  
1.8  
1.8  
1.7  
1.7  
1.6  
1.6  
70  
Unit  
MHz  
ns  
I
t
t
t
t
t
t
t
t
Input Clock Frequency Range Non-crystal, 3.0V Pk–Pk ext. source  
CLKFR  
Clock Rise Time  
SSCLK1a or SSCLK1b, Freq = 100 MHz  
SSCLK1a or SSCLK1b, Freq = 100 MHz  
SSCLK1(a+b), CL = 33 pF, 100 MHz  
SSCLK1(a+b), CL = 33 pF, 100 MHz  
SSCLK1(a+b), CL = 33 pF, 200 MHz  
SSCLK1(a+b), CL = 33 pF, 200 MHz  
REFOUT, Pin 3, CL = 15 pF, 50 MHz  
REFOUT, Pin 3, CL = 15 pF, 50 MHz  
XIN/CLK (Pin)  
1.0  
1.0  
1.2  
1.2  
1.1  
1.1  
1.0  
1.0  
30  
1.3  
1.3  
1.5  
1.5  
1.4  
1.4  
1.3  
1.3  
50  
RISE(a)  
Clock Fall Time  
ns  
FALL(a)  
Clock Rise Time  
ns  
RISE(a+b)  
FALL(a+b)  
RISE(a+b)  
FALL(a+b)  
RISE(REF)  
FALL(REF)  
Clock Fall Time  
ns  
Clock Rise Time  
ns  
Clock Fall Time  
ns  
Clock Rise Time  
ns  
Clock Fall Time  
ns  
D
D
C
C
Input Clock Duty Cycle  
Output Clock Duty Cycle  
Cycle-to-Cycle Jitter  
Cycle-to-Cycle Jitter  
Refout Frequency Range  
%
TYin  
TYout  
CJ1  
SSCLK1a/b (Pin 8 and 9)  
45  
50  
55  
%
F = 100 MHz, SSCLK1a/b CL = 33 pF  
F = 200 MHz, SSCLK1a/b CL = 33 pF  
CL = 15 pF  
300  
500  
400  
600  
108  
ps  
ps  
CJ2  
REFOUT  
25  
MHz  
Note:  
1. Operation at any Absolute Maximum Rating is not implied.  
2. Single Power Supply: The voltage on any input or I/O pin cannot exceed the power pin during power-up.  
Document #: 38-07429 Rev. *B  
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CY25566  
Ordering Information  
Part Number  
CY25566SC  
Package Type  
Product Flow  
Commercial, 0° to 70°C  
16-pin SOIC  
16-pin SOIC–Tape and Reel  
CY25566SCT  
Commercial, 0° to 70°C  
Package Drawing and Dimensions  
16-Lead (150-Mil) SOIC S16.15  
PIN 1 ID  
8
1
DIMENSIONS IN INCHES[MM] MIN.  
MAX.  
REFERENCE JEDEC MS-012  
PACKAGE WEIGHT 0.15gms  
0.150[3.810]  
0.157[3.987]  
0.230[5.842]  
0.244[6.197]  
PART #  
S16.15 STANDARD PKG.  
SZ16.15 LEAD FREE PKG.  
9
16  
0.010[0.254]  
0.016[0.406]  
X 45°  
0.386[9.804]  
0.393[9.982]  
SEATING PLANE  
0.061[1.549]  
0.068[1.727]  
0.004[0.102]  
0.050[1.270]  
BSC  
0.0075[0.190]  
0.0098[0.249]  
0.016[0.406]  
0.035[0.889]  
0°~8°  
0.0138[0.350]  
0.0192[0.487]  
0.004[0.102]  
0.0098[0.249]  
51-85068-*B  
All product and company names mentioned in this document are the trademarks of their respective holders.  
Document #: 38-07429 Rev. *B  
Page 8 of 9  
© Cypress Semiconductor Corporation, 2002. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use  
of any circuitry other than circuitry embodied in a Cypress Semiconductor product. Nor does it convey or imply any license under patent or other rights. Cypress Semiconductor does not authorize  
its products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress  
Semiconductor products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress Semiconductor against all charges.  
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CY25566  
Document Title:CY25566 Spread Spectrum Clock Generator  
Document Number: 38-07429  
Issue  
Date  
Orig. of  
Change  
Rev.  
ECN No.  
Description of Change  
**  
115771  
122705  
404070  
07/01/02  
12/30/02  
See ECN  
OXC  
RBI  
New Data Sheet  
*A  
*B  
Added power up requirements to maximum ratings information.  
Minor Change: Typo error on table 1, column 2 , S0 = 0 (not M)  
RGL  
Document #: 38-07429 Rev. *B  
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