Cypress Semiconductor CY25818 Manuale utente

Spread Spectrum Clock Generato

CY25818/19

Cypress Semiconductor Corporation • 198ChampionCourt • San Jose,CA 95134-1709 • 408-943-2600

Document #: 38-07362 Rev. *B Revised April 11, 2006

Features

• 8- to 32-MHz input frequency range

• CY25818: 8–16 MHz

• CY25819: 16–32 MHz

• Separate modulated and unmodulated clocks

• Accepts clock, crystal, and resonator inputs

• Down spread modulation

• Power-down function

• Low-power dissipation

— CY25818 = 33 mW-typ @ 8 MHz

— CY25818 = 56 mW-typ @ 16 MHz

— CY25819 = 36 mW-typ @ 16 MHz

— CY25819 = 63 mW-typ @ 32 MHz

• Low cycle-to-cycle jitter

— SSCLK = 250 ps-typ

— REFOUT = 275 ps-typ

• Available in 8-pin (150-mil) SOIC package

Applications

• Printers and MFPs

• LCD panels and notebook PCs

• Digital copiers

•PDAs

• Automotive

• CD-ROM, VCD, and DVD

• Networking and LAN/WAN

•Scanners

•Modems

• Embedded digital systems

Benefits

• Peak electromagnetic interference (EMI) reduction by

8–16 dB

• Fast time to market

• Cost reduction

REFERENCE

DIVIDER PD and

CP LF

VCO

DIVIDER

and

MUX

INPUT

DECODER

300K

MODULATION

CONTROL

3 6

S0 PD#

XIN/CLKIN

XOUT

VDD 7

VSS 2

4SSCLK

5REFCLK

VCO

COUNTER

XIN/CLKIN

Vss

SSCLK

XOUT

Vdd

PD#

REFCLK

CY25818

CY25819

8 Pin SOIC

8-pin SOIC

Block Diagram Pin Configuration

[+] Feedback

CY25818/19

Document #: 38-07362 Rev. *B Page 2 of 7

Overview

The Cypress CY25818/19 products are Spread Spectrum

Clock Generator (SSCG) ICs used for the purpose of reducing

EMI found in today’s high-speed digital electronic systems.

The devices use a Cypress proprietary phase-locked loop

(PLL) and Spread Spectrum Clock (SSC) technology to

synthesize and modulate the frequency of the input clock. By

frequency modulating the clock, the measured EMI at the

fundamental and harmonic frequencies is greatly reduced.

This reduction in radiated energy can significantly reduce the

cost of complying with regulatory agency requirements and

improve time to market without degrading system perfor-

mance.

The input frequency range is 8–16 MHz for the CY25818 and

16–32 MHz for the CY25819. Both products accept external

clock, crystal, or ceramic resonator inputs.

The CY25818/19 provide separate modulated (SSCLK) and

unmodulated reference (REFCLK) clock outputs which are the

same frequency as the input clock frequency. Down spread

frequency modulation can be selected by the user, based on

three discrete values of Spread%. A separate power down

function is also provided.

The CY25818/19 products are available in an 8-pin SOIC

(150-mil) package with a commercial operating temperature

range of 0–70°C. Contact Cypress for availability of –40 to

+85°C industrial temperature range operation or TSSOP

package versions. Refer to the CY25568, CY25811,

CY25812, and CY25814 products for other functions such as

clock multiplication of 1×, 2×, or 4× to generate a wide range

of Spread Spectrum output clocks from 4 to 128 MHz.

Input Frequency Range and Selection

CY25818/19 input frequency range is 8–32 MHz. This range

is divided into two segments, as given in Table 1.

Spread% Selection

CY25818/19 SSCG products provide Down-Spread frequency

modulation. The amount of Spread% is selected by using

3-Level S0 digital input. Spread% values are given in Table 2.

Pin Description

Pin Name Description

1 XIN/CLK Clock, Crystal, or Ceramic Resonator Input Pin.

2 Vss Power Supply Ground.

3 S0 Digital Spread% Control Pin. 3-Level input (H-M-L). Default = M.

4 SSCLK Modulated Spread Spectrum Output Clock. The output frequency is referenced to input frequency. Refer

to Table 2 for the amount of modulation (Spread%).

5REFCLK

Unmodulated Reference Clock Output. The unmodulated output frequency is the same as the input

frequency.

6 PD# Power-Down Control Pin. Default = H (Vdd).

7 Vdd Positive Power Supply.

8XOUT

Clock, Crystal, or Ceramic Resonator Output Pin. Leave this pin unconnected if an external clock is used

at XIN pin.

Table 1. Input and Output Frequency Selection

Product Input/Output Frequency Range

CY25818 8–16 MHz

CY25819 16–32 MHz

Table 2. Spread% Selection

XIN (MHz) Product S0 = 1 S0 = 0 S0 = M

Down (%) Down (%) Down (%)

8–10 CY25818 –3.0 –2.2 –0.7

10–12 CY25818 –2.7 –1.9 –0.6

12–14 CY25818 –2.5 –1.8 –0.6

14–16 CY25818 –2.3 –1.7 –0.5

16–20 CY25819 –3.0 –2.2 –0.7

20–24 CY25819 –2.7 –1.9 –0.6

24–28 CY25819 –2.5 –1.8 –0.6

28–32 CY25819 –2.3 –1.7 –0.5

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CY25818/19

Document #: 38-07362 Rev. *B Page 3 of 7

3-Level Digital Inputs

S0 digital input is designed to sense three logic levels desig-

nated as HIGH “1,” LOW “0,” and MIDDLE “M.” With this

3-Level digital input logic, the 3-Level logic is able to detect

three different logic levels.

The S0 pin includes an on-chip 20K (10K/10K) resistor divider.

No external application resistors are needed to implement

3-Level logic, as follows.

Logic Level “0”: 3-Level logic pin connected to GND.

Logic Level “M”: 3-Level logic pin left floating (no connection.)

Logic Level “1”: 3-Level logic pin connected to Vdd.

Figure 1 illustrates how to implement 3-Level Logic.

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.

The Modulation Rates of SSCG clocks are generally referred

to in terms of frequency, and fmod = 1/Tmod.

The input clock frequency, fin, and the internal divider

determine the Modulation Rate.

In the case of CY25818/19 devices, the (Spread Spectrum)

Modulation Rate, fmod, is given by the following formula:

fmod = fIN/DR

where fmod is the Modulation Rate, fIN is the Input Frequency,

and DR is the Divider Ratio, as given in Table 3.

Maximum Ratings[1, 2]

Supply Voltage (Vdd): ..................................................+ 5.5V

Input Voltage Relative to Vdd:..............................Vdd + 0.3V

Input Voltage Relative to Vss:...............................Vss + 0.3V

Operating Temperature:................................... 0°C to + 70°C

Storage Temperature:................................ –65°C to + 150°C

LOGIC

LOW (0) LOGIC

MIDDLE (M) LOGIC

HIGH (H)

to VDD

UNCONNECTED

to VSS

VDD

VSS Figure 1. 3-Level Logic

Table 3. Modulation Rate Divider Ratios

Product Input Frequency Range Divider Ratio (DR)

CY25818 8–16 MHz 256

CY25819 16–32 MHz 512

Table 4. DC Electrical Characteristics Vdd = 3.3V ±10%, TA= 0°C to +70°C and CL = 15 pF (unless otherwise noted)

Parameter Description Conditions Min. Typ. Max. Unit

Vdd Power Supply Range 2.97 3.3 3.63 V

VINH Input HIGH Voltage S0 Input 0.85 Vdd Vdd Vdd V

VINM Input MIDDLE Voltage S0 Input 0.40 Vdd 0.50 Vdd 0.60 Vdd V

VINL Input LOW Voltage S0 Input 0.0 0.0 0.15 Vdd V

VOH1 Output HIGH Voltage IOH = 4 ma, SSCLK and REFCLK 2.4 – – V

VOH2 Output HIGH Voltage IOH = 6 ma, SSCLK and REFCLK 2.0 – – V

VOL1 Output LOW Voltage IOL = 4 ma, SSCLK Output – – 0.4 V

VOL2 Output LOW Voltage IOL = 10 ma, SSCLK Output – – 1.2 V

CIN1 Input Capacitance XIN (Pin 1) and XOUT (Pin 8) 6.0 7.5 9.0 pF

CIN2 Input Capacitance All Digital Inputs 3.5 4.5 6.0 pF

IDD1 Power Supply Current FIN=8 MHz, no load – 10.0 12.5 mA

IDD3 Power Supply Current FIN=32 MHz, no load – 19.0 23.0 mA

IDD4 Power Supply Current PD# = Vss – 150 250 mA

[+] Feedback

CY25818/19

Document #: 38-07362 Rev. *B Page 4 of 7

Characteristics Curves

The following curves demonstrate the characteristic behavior

of the CY25818/19 when tested over a number of environ-

mental and application specific parameters. These are typical

performance curves and are not meant to replace any

parameter specified in Table 4 and Table 5.

Notes:

1. Single Power Supply: The voltage on any input or I/O pin cannot exceed the power pin during power-up.

2. Operation at any Absolute Maximum Rating is not implied.

Table 5. Timing Electrical Characteristics Vdd = 3.3V ±10%, TA= 0°C to +70°C and CL= 15 pF (unless otherwise noted)

Parameter Description Conditions Min. Typ. Max. Unit

ICLKFR1 Input Frequency Range CY25818 8 – 16 MHz

ICLKFR2 Input Frequency Range CY25819 16 – 32 MHz

trise1 Clock Rise Time SSCLK and REFCLK, 0.4V to 2.4V 2.0 3.0 4.0 ns

tfall1 Clock Fall Time SSCLK and REFCLK, 0.4V to 2.4V 2.0 3.0 4.0 ns

CDCin Input Clock Duty Cycle XIN 20 50 80 %

CDCout Output Clock Duty Cycle SSCLK and REFCLK @ 1.5V 45 50 55 %

CCJss Cycle-to-Cycle Jitter SSCLK; FIN = FOUT = 8–32 MHz 250 350 ps

CCJref Cycle-to-Cycle Jitter REFCLK; FIN = FOUT = 8–32 MHz 275 375 ps

200

210

220

230

240

250

260

270

280

290

300

8 121620242832

Frequency (MHz)

CCJ (ps)

REFCLK CY25818

SSCLK CY25818

REFCLK CY25819

SSCLK CY25819

Figure 2. CCJ (ps) vs. Frequency (MHz)

1.75

2.25

2.5

2.75

-40 -25 -10 5 20 35 50 65 80 95 110 125

Temp (C)

BW %

12 MHz

32.0MHz

Figure 3. Bandwidth% vs. Temperature

8 121620242832

Frequency (MHz)

IDD(mA

)

CY25819

16 - 32 MHz

CY25818

8 - 16 MHz

Figure 4. IDD (mA) vs. Frequency (MHz)

1.8

1.9

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.1

2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 3.7

VDD (volts)

BW (%)

CY25819@32 MHz

CY25818@8.0 MHz

Figure 5. Bandwidth% vs. Vdd

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CY25818/19

Document #: 38-07362 Rev. *B Page 5 of 7

SSCG Profiles

CY25818/19 SSCG products use a non-linear “optimized”

frequency profile as shown in Figure 6 and Figure 7. The use

of Cypress proprietary “optimized” frequency profile maintains

flat energy distribution over the fundamental and higher order

harmonics. This results in additional EMI reduction in

electronic systems.

Application Schematic

Notes:

3. XIN = 16.0 MHz; S0 = 1; SSCLK = 16.0 MHz; BW = –2.14%.

4. Xin = 32.0MHz; S0 = 1; SSCLK = 32.0 MHz; BW = -2.15%

Figure 6. CY25818Spread Spectrum Profile

(Frequency vs. Time)[3]

Figure 7. CY25819 Spread Spectrum Profile

(Frequency vs. Time)[4]

Vdd

14.3 MHz

27.0 MHz

Vss S0

XIN

XOUT

SSCLK

Vdd

CY25818

CY25819

0.1 uF

27 pF

14.3 MHz (CY25818)

27.0 MHz (CY25819)

REFCLK 5

PD#

Figure 8. Typical Application Schematic

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CY25818/19

Document #: 38-07362 Rev. *B Page 6 of 7

of any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be

used for medical, life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress 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

products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.

Package Drawing and Dimensions

All product and company names mentioned in this document may be the trademarks of their respective holders.

Ordering Information

Part Number Package Type Product Flow

CY25818SC 8-pin SOIC Commercial, 0°to 70°C

CY25818SCT 8-pin SOIC–Tape and Reel Commercial, 0°to 70°C

CY25819SC 8-pin SOIC Commercial, 0°to 70°C

CY25819SCT 8-pin SOIC–Tape and Reel Commercial, 0°to 70°C

Lead-free

CY25818SXC 8-pin SOIC Commercial, 0°to 70°C

CY25818SXCT 8-pin SOIC–Tape and Reel Commercial, 0°to 70°C

CY25819SXC 8-pin SOIC Commercial, 0°to 70°C

CY25819SXCT 8-pin SOIC–Tape and Reel Commercial, 0°to 70°C

SEATING PLANE

PIN1ID

0.230[5.842]

0.244[6.197]

0.157[3.987]

0.150[3.810]

0.189[4.800]

0.196[4.978]

0.050[1.270]

BSC

0.061[1.549]

0.068[1.727]

0.004[0.102]

0.0098[0.249]

0.0138[0.350]

0.0192[0.487]

0.016[0.406]

0.035[0.889]

0.0075[0.190]

0.0098[0.249]

1. DIMENSIONS IN INCHES[MM] MIN.

MAX.

0°~8°

0.016[0.406]

0.010[0.254] X 45°

2. PIN1IDISOPTIONAL,

ROUND ON SINGLE LEADFRAME

RECTANGULAR ON MATRIX LEADFRAME

0.004[0.102]

8 Lead (150 Mil) SOIC - S08

3. REFERENCE JEDEC MS-012

PART #

S08.15 STANDARD PKG.

SZ08.15 LEAD FREE PKG.

4. PACKAGE WEIGHT 0.07gms

8-lead (150-Mil) SOIC S8

51-85066-*C

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CY25818/19

Document #: 38-07362 Rev. *B Page 7 of 7

Document History Page

Document Title: CY25818/19 Spread Spectrum Clock Generator

Document Number: 38-07362

REV. ECN NO. Issue

Date Orig. of

Change Description of Change

** 112462 03/21/02 OXC New Data Sheet

*A 122701 12/28/02 RBI Added power up requirements to maximum rating information.

*B 448097 See ECN RGL Add Lead-free devices

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