Manual do usuário Cypress CY25818

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CY25818/19
Spread Spectrum Clock Generator
Features Applications
• 8- to 32-MHz input frequency range • Printers and MFPs
• CY25818: 8–16 MHz • LCD panels and notebook PCs
• CY25819: 16–32 MHz • Digital copiers
• Separate modulated and unmodulated clocks •PDAs
• Accepts clock, crystal, and resonator inputs • Automotive
• Down spread modulation • CD-ROM, VCD, and DVD
• Power-down function • Networking and LAN/WAN
• Low-power dissipation •Scanners
— CY25818 = 33 mW-typ @ 8 MHz •Modems
— CY25818

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CY25818/19 . 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. Modulated Spread Spectrum Output Clock. The output frequency is referenced to input frequency. Refer 4 SSCLK to Table 2 for the amount of modulation (Spread%). Unmodulated Reference Clock Output. The unmodulated output frequency is the same as the input 5REFCLK frequency. 6 PD# Power-Down C

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CY25818/19 3-Level Digital Inputs Modulation Rate S0 digital input is designed to sense three logic levels desig- Spread Spectrum Clock Generators utilize frequency nated as HIGH “1,” LOW “0,” and MIDDLE “M.” With this modulation (FM) to distribute energy over a specific band of 3-Level digital input logic, the 3-Level logic is able to detect frequencies. The maximum frequency of the clock (fmax) and three different logic levels. minimum frequency of the clock (fmin) determine this band of fre

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CY25818/19 Table 5. Timing Electrical Characteristics Vdd = 3.3V ±10%, T = 0°C to +70°C and C = 15 pF (unless otherwise noted) A L 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 X 20 50 80 % IN CDCout Output Clock Duty Cycle

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CY25818/19 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. Figure 7. CY25819 Spread Spectrum Profile [4] (Frequency vs. Time) Figure 6. CY25818 Spread Spectrum Profile [3] (Frequency vs. Time) Application Schematic

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CY25818/19 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,

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CY25818/19 Document History Page Document Title: CY25818/19 Spread Spectrum Clock Generator Document Number: 38-07362 Issue Orig. of REV. ECN NO. Date 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 Document #: 38-07362 Rev. *B Page 7 of 7 [+] Feedback