Infineon Technologies CY2309SI-1

Overview

CY2309SI-1 from Cypress Semiconductor is a 3.3V industrial-grade zero-delay clock buffer with PLL-based architecture, 9 low-skew outputs (4+4+1 banked configuration), 10–133 MHz operating range, and 85 ps typical output-to-output skew. It serves as a clock distribution IC in Pentium-based embedded systems requiring precise timing synchronization across multiple peripherals.

For engineers reviewing the CY2309SI-1 datasheet, CY2309SI-1 pinout, CY2309SI-1 application, or CY2309SI-1 equivalent, key selection criteria include industrial temperature support (–40°C to +85°C), test-mode bypass capability via S1/S2 select inputs, zero input-output propagation delay under matched loading, and compatibility with PCI/SDRAM bus clocking requirements.

Technical Context

The CY2309SI-1 integrates an on-chip PLL with internal feedback sourced from the CLKOUT pin, enabling zero input-output delay when all outputs-including CLKOUT-are uniformly loaded. Its dual-bank output structure (Bank A: CLKA1–CLKA4; Bank B: CLKB1–CLKB4) supports selective enable/disable via S1/S2 control logic.

PLL lock time is ≤1.0 ms under stable supply and valid REF input; power-down mode activates automatically when REF has no rising edges, reducing supply current to ≤25.0 μA. The device supports PLL bypass in test mode (S2=0, S1=0), delivering direct REF-to-output path with 1–8.7 ns delay.

Key Specifications

Pinout & Package

Package: 16-pin 4.4-mm TSSOP (JEDEC MO-153) or 150-mil SOIC; pin-compatible with CY2309SC-1 and CY2309SI-1H variants.

Key Features

Applications

Equivalent & Alternatives

Two functionally compatible alternatives exist for CY2309SI-1 in industrial clock distribution applications:

Compared with IDT 5V991A-1JGI and ON Semi NB3N3020DR2G, CY2309SI-1 uniquely combines industrial temperature rating, dual-bank control, PLL bypass, and 85 ps skew-making it the only option for field-upgradable, testable, and thermally robust clock trees in legacy x86 industrial platforms.

Availability

CY2309SI-1 is available at Aetrix Electronics and suitable for PCI bus clock distribution, SDRAM memory controller timing, and Pentium-based industrial CPU board designs requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CY2309SI-1 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 Technologies) designs high-reliability timing, memory, and microcontroller solutions for industrial, automotive, and communications markets.

CY2309 belongs to Cypress's zero-delay buffer product line, engineered specifically for clock distribution in legacy x86 and PCI-based embedded systems where deterministic skew and industrial temperature operation are mandatory.

FAQ

What is the required load on CLKOUT to achieve zero input-output delay?

CLKOUT must be loaded with identical capacitive load as all other outputs-typically 30 pF below 100 MHz or 10 pF from 100–133 MHz-to maintain zero REF-to-output delay. Even if unused, CLKOUT requires this matching load; omitting it introduces up to ±350 ps delay variation due to PLL feedback path imbalance.

How does the S1/S2 select logic affect output behavior in CY2309SI-1?

S1 and S2 are weak-pull-up inputs that decode into four modes: (0,0) three-states all outputs except CLKOUT; (0,1) enables Bank A only; (1,0) enables both banks; (1,1) enables both banks with PLL active. This allows dynamic partitioning of clock resources and system-level test isolation without external logic.

Can CY2309SI-1 drive 50Ω transmission lines directly?

No-CY2309SI-1 outputs are CMOS-compatible with 8 mA sink/source drive strength and require external series or parallel termination. Driving 50Ω lines directly causes signal integrity degradation; recommended practice is 33Ω series resistor at source plus 50Ω parallel termination at receiver for point-to-point traces.

Is the 85 ps output-to-output skew guaranteed over the full industrial temperature range?

Yes-the 85 ps typical skew is characterized from –40°C to +85°C and specified as ≤250 ps maximum across temperature and voltage. This guarantee holds only when all outputs are equally loaded with ≤30 pF capacitance and routed with matched trace lengths and impedance.