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Infineon Technologies CY28RS400ZXCT
- Part No.:
- CY28RS400ZXCT
- Manufacturer:
- Infineon Technologies
- Category:
- Application Specific Clock/Timing
- Package:
- 56-TFSOP (0.240", 6.10mm Width)
- Datasheet:
-
CY28RS400ZXCT.pdf
- Description:
- IC CLK GEN CPU 266MHZ 2CIRC
- Quantity:
- Payment:
- Shipping:
Inventory:2,963
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Product details
Overview
CY28RS400ZXCT from Cypress Semiconductor is a dedicated clock generator for the ATI RS400 chipset, providing synchronized differential CPU (up to 266 MHz), 100-MHz SRC, 33-MHz PCI, 48-MHz USB, and 14.318-MHz REF clocks. It integrates dual PLLs, I²C programmability, and Lexmark spread-spectrum EMI reduction. Designed for Intel-compatible desktop platforms with VTT power-good sequencing.
For engineers reviewing the CY28RS400ZXCT datasheet, CY28RS400ZXCT pinout, CY28RS400ZXCT application, or CY28RS400ZXCT equivalent, this device requires attention to FS_A/FS_B/FS_C frequency select latching via VTT_PWRGD#, I²C register-level control of individual clock enables/drive strength, and strict parallel-resonance crystal loading compliance.
Technical Context
The CY28RS400ZXCT implements two independent PLLs: one for CPU/SRC outputs (with selectable overclocking via SMBus) and another for PCI/USB/REF clocks. Frequency selection is latched on VTT_PWRGD# assertion using FS_A/FS_B/FS_C and PCI0/409_410 inputs, locking configuration before system boot.
I²C interface (7-bit slave address 0xD2) supports byte/block read/write operations for runtime control of output enables, spread-spectrum depth (–0.35% or –0.50%), drive strength (1×/2×), and CLKREQ#-gated stop modes. All clock outputs use Intel Type-X (differential) or Type-3A/5 (single-ended) buffer standards.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| CPU Clock Output | Up to 266 MHz differential (Intel Type-X), selectable via 3-bit FS input latching |
| SRC Clock Output | 100 MHz differential (SRCT/C[5:0]), individually enable/disable via I²C register Byte 0 |
| USB Clock | 48 MHz single-ended (Intel Type-3A), drive strength configurable (1×/2×) in Register 2 |
| PCI Clock | 33 MHz single-ended (Intel Type-5), output enable and drive strength controlled via I²C |
| Spread Spectrum | Lexmark-compliant EMI reduction: –0.35% or –0.50% depth, globally or per-domain enabled |
| Supply Voltage | 3.3 V only; separate power domains for CPU, SRC, PCI, REF, USB, and analog (VDDA/VSSA) |
| Interface | I²C-compatible serial bus (SCLK/SDATA), 7-bit slave address 0xD2, supports block/byte R/W |
Pinout & Package
56-pin SSOP/TSSOP package with segregated power/ground domains per clock group and dedicated analog supply (VDDA/VSSA) for PLL stability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| XIN / XOUT | Crystal oscillator interface | 14.318-MHz parallel-resonance crystal connection; incorrect series-resonance crystal causes >300-ppm frequency error |
| CPUT2/CPUT1/CPUT0, CPUC2/CPUC1/CPUC0 | CPU clock outputs | Differential pairs (Type-X); gated by CPU_STP# with 2-cycle disable latency |
| SRCT5–SRCT0 / SRCC5–SRCC0 | SRC clock outputs | 100-MHz differential outputs; individually controllable via I²C Byte 0 |
| USB_48 | USB clock output | 48-MHz single-ended (Type-3A); drive strength set in Register 2 Bit 6 |
| REF0/REF1/REF2 | Reference clock outputs | 14.318-MHz single-ended (Type-5); REF0/REF1 also serve as CPU frequency select inputs |
| FSC, FS_A, FS_B, FS_C, PCI0/409_410 | Frequency select inputs | Latched on VTT_PWRGD# falling edge; determine CPU frequency table (CK409/CK410) and output rates |
| SCLK / SDATA | I²C interface | SMBus-compatible; internal pull-ups; tri-stated in power-down mode |
| VTT_PWRGD# | Power-good strobe | Level-sensitive input that latches FS inputs and enables configuration lock; transitions ignored after first valid low |
Key Features
| Feature | Design Value |
|---|---|
| Dual PLL architecture | Independent CPU/SRC and PCI/USB/REF PLLs enable simultaneous multi-frequency synthesis without crosstalk |
| VTT_PWRGD#-latched configuration | Hardware-based frequency selection eliminates BIOS/software dependency for boot-critical clock setup |
| Lexmark spread-spectrum profile | Pre-certified EMI reduction at –0.35% or –0.50% modulation depth, compliant with FCC/CE radiated emission limits |
| I²C register-level output control | Per-clock enable/disable, drive strength, and stop-mode behavior configurable post-power-up without reset |
| Multi-domain power isolation | Dedicated VDD_CPU, VDD_SRC, VDD_PCI, VDD_REF, VDD_48, and VDDA supplies minimize noise coupling between clock groups |
Applications
| ATI RS400-Based Desktop Motherboards | Intel Pentium 4 / Celeron Platform Designs |
|---|---|
Use Scenario: Mainboard clock subsystem for AMD/ATI RS400 chipset with Intel CPU support. IC Role / Device Role / Timing Role: Primary clock synthesizer generating all core platform clocks (CPU, SRC, PCI, USB, REF) with strict timing alignment. Use Value: Eliminates need for multiple discrete oscillators; ensures Intel Type-X buffer compliance and CK409/CK410 frequency table adherence. |
Use Scenario: High-volume OEM desktop platform requiring BIOS-independent clock initialization. IC Role / Device Role / Timing Role: Hardware-latched clock generator enabling reliable boot under varying VTT ramp conditions. Use Value: VTT_PWRGD#-triggered FS input sampling guarantees deterministic frequency selection before CPU reset release. |
| EMI-Sensitive Consumer Electronics | Industrial Embedded Systems with Legacy PCI |
Use Scenario: Compact form-factor PC with metal chassis requiring radiated emissions compliance. IC Role / Device Role / Timing Role: Spread-spectrum clock source with Lexmark-optimized modulation for FCC Class B certification. Use Value: Reduces peak radiated emissions by >10 dB without altering signal integrity or timing margins. |
Use Scenario: Industrial control board integrating legacy PCI peripherals and USB 1.1 interfaces. IC Role / Device Role / Timing Role: Single-chip source for 33-MHz PCI, 48-MHz USB, and 14.318-MHz REF clocks with independent enable control. Use Value: Enables selective clock gating during low-power states while maintaining PCI bus timing requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar clock generator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ICS952006AGT | Single PLL architecture; no dual-domain spread spectrum; 48-pin TSSOP | Lacks VTT_PWRGD# latching and CK409/CK410 table support; limited to fixed-frequency PCI/USB outputs | Use only if platform does not require overclock-capable SRC clocks or Lexmark EMI profile. |
| ICS952606AGT | Supports DDR2 memory clocks; includes phase-locked loop margining; 64-pin TQFP | Designed for Intel 945/965 chipsets; incompatible FS input mapping and REF clock routing | Select only for newer Intel platforms requiring DDR2 timing; not drop-in for RS400 designs. |
Compared with ICS952006AGT and ICS952606AGT, the CY28RS400ZXCT uniquely provides hardware-latched CK409/CK410 frequency selection, dual PLL isolation, and Lexmark-specified spread-spectrum modulation-critical for RS400-based systems requiring EMI compliance and CPU overclock flexibility.
Availability
CY28RS400ZXCT is available at Aetrix Electronics and suitable for ATI RS400 motherboard designs, Intel Pentium 4 platform builds, and industrial PCI/USB timing applications requiring stable component supply across extended production cycles.
Supply support for CY28RS400ZXCT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Cypress Semiconductor (now part of Infineon) is a fabless semiconductor company specializing in timing, memory, and programmable logic solutions for computing and communications infrastructure.
The CY28RS400 belongs to Cypress's legacy clock generator product line, engineered specifically for AMD/ATI chipset reference designs requiring Intel CPU compatibility, multi-rail power isolation, and hardware-configurable spread spectrum.
FAQ
What crystal type and load capacitance does the CY28RS400ZXCT require?
The CY28RS400ZXCT requires a parallel-resonance crystal-not series-resonance-to meet ppm specifications. Total load capacitance on each crystal terminal must be twice the crystal's specified CL value due to series-connected trim capacitors. Typical CL is 12–18 pF; trace and pin capacitance must be included in calculation.
How is CPU frequency selected, and can it be changed after power-up?
CPU frequency is selected by latching FS_A, FS_B, FS_C, and PCI0/409_410 logic levels on the falling edge of VTT_PWRGD#. Once latched, the configuration is immutable until next power cycle. No runtime frequency reconfiguration is supported-the I²C interface controls only output enables and drive settings.
Does the CY28RS400ZXCT support spread-spectrum clocking on all outputs?
No. Spread spectrum is configurable per domain: Bit 7 of Control Register 2 selects –0.35% or –0.50% depth for CPUT/C and SRCT/C outputs only. USB_48 and PCI outputs do not support spread spectrum; REF outputs are fixed-frequency and unmodulated.
What is the function of the CLKREQ#0 and CLKREQ#1 pins?
CLKREQ#0 and CLKREQ#1 are Minicard-compliant output-enable controls for SRCT/C clocks. When asserted high, they place selected SRCT/C outputs into high-impedance state. Individual mapping to SRCT/C[5:0] is configured via I²C Registers 4 and 5, enabling selective clock gating per peripheral request.
CY28RS400ZXCT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Infineon Technologies
- Series:
- -
- Package/Case:
- 56-TFSOP (0.240", 6.10mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- PLL:
- Yes
- Main Purpose:
- CPU Graphics
- Input:
- LVTTL, Crystal
- Output:
- Clock
- Number of Circuits:
- 2
- Ratio - Input:Output:
- -
- Differential - Input:Output:
- No/Yes
- Frequency - Max:
- 266MHz
- Voltage - Supply:
- 3.135V ~ 3.465V
- Operating Temperature:
- 0°C ~ 70°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 56-TSSOP II
CY28RS400ZXCT FAQ
1.How can I place an order for CY28RS400ZXCT through Aetrix?
Please submit a Request for Quotation (RFQ) for CY28RS400ZXCT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for CY28RS400ZXCT reliable?
The price and inventory of CY28RS400ZXCT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CY28RS400ZXCT is usually 5 days.
3.What payment methods are accepted for CY28RS400ZXCT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CY28RS400ZXCT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CY28RS400ZXCT?
CY28RS400ZXCT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CY28RS400ZXCT order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for CY28RS400ZXCT?
For technical support, including CY28RS400ZXCT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CY28RS400ZXCT requirements.
6.How does Aetrix verify that CY28RS400ZXCT is sourced from the original manufacturer or authorized distributors?
All CY28RS400ZXCT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that CY28RS400ZXCT meets industry standards.
7.What is the process for return or replacement of CY28RS400ZXCT?
All CY28RS400ZXCT units undergo pre-shipment inspection (PSI). If there is an issue with CY28RS400ZXCT, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The CY28RS400ZXCT part is unused and in its original packaging.
Return procedure for CY28RS400ZXCT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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