Infineon Technologies CY2308SI-1

Overview

CY2308SI-1 from Cypress Semiconductor is a 3.3V zero-delay clock buffer with on-chip PLL, designed to distribute high-speed reference clocks in PC, workstation, and telecom systems. It delivers 10–133.3 MHz output frequency, <200 ps output-to-output skew, 75 ps typical cycle-to-cycle jitter at 66.67 MHz (15 pF), and supports two independently three-stateable banks of four outputs.

For engineers reviewing the CY2308SI-1 datasheet, CY2308SI-1 pinout, CY2308SI-1 application, or CY2308SI-1 equivalent, this device is selected for low-skew clock fanout where input-output propagation delay must be nulled via feedback loading, PLL lock time ≤1.0 ms is required, and industrial temperature operation (–40°C to +85°C) is needed.

Technical Context

The CY2308SI-1 implements a PLL-based zero-delay architecture where the REF input drives an internal phase-locked loop, and the FBK pin closes the loop using one of its eight clock outputs. Feedback path selection determines whether both banks output the reference frequency (1×) - confirming its identity as the base configuration part.

It features dual-bank output control via S1/S2 select inputs, enabling independent three-state control per bank or bypass mode (REF directly routed to outputs). The PLL shuts down automatically when REF lacks rising edges, reducing supply current to ≤25 μA in power-down mode under industrial conditions.

Key Specifications

Pinout & Package

Package: 16-pin SOIC (150 mil, 3.9 mm × 9.9 mm), RoHS-compliant, industrial temperature rated.

Key Features

Applications

Equivalent & Alternatives

CY2308SI-1 has documented alternatives for specific performance or packaging needs.

Compared with CY2308ZC-1 and CY2308SXI-1, the CY2308SI-1 provides the standard industrial temperature grade in the widely adopted SOIC-16 footprint - making it the preferred choice for cost-sensitive, thermally stable applications requiring proven long-term supply continuity.

Availability

CY2308SI-1 is available at Aetrix Electronics and suitable for PCI-X bus clock distribution, Gigabit Ethernet PHY timing, and DDR memory controller clock tree applications requiring stable component supply, long-lifecycle support, and industrial temperature qualification.

Supply support for CY2308SI-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-performance timing, memory, and microcontroller solutions for computing, networking, and industrial markets.

The CY2308 product line delivers zero-delay clock buffering with integrated PLLs - engineered specifically for high-speed digital systems needing deterministic, low-jitter clock fanout without external delay compensation.

FAQ

What is the minimum load capacitance supported for stable 133.3 MHz operation?

The CY2308SI-1 supports 133.3 MHz operation only with ≤15 pF total load capacitance on each output, as specified in the Industrial Temperature Switching Characteristics table. Exceeding 15 pF at this frequency risks increased jitter (>100 ps) and potential PLL unlock due to phase margin degradation. Layout must minimize trace capacitance and avoid stubs.

How does the FBK pin achieve zero input-output delay?

Zero delay is achieved by routing one output (e.g., CLKA1) to the FBK pin and matching its capacitive load (e.g., 7 pF + PCB trace) to that of all other outputs. The internal PLL adjusts phase until the delay from REF to that output equals the delay from REF to FBK - resulting in net zero propagation delay. Mismatched loading introduces predictable, adjustable delay.

Can S1 and S2 be left floating in the circuit?

No - S1 and S2 have internal weak pull-ups and must be actively driven to defined logic levels (VDD or GND) to ensure deterministic bank enable/disable behavior. Floating inputs may cause metastability, unintended three-state transitions, or erratic PLL shutdown, especially during power-up or ESD events.

Is the CY2308SI-1 pin-compatible with CY2308SXI-1?

Yes - both parts use identical 16-pin SOIC packages with identical pinout, electrical interface, and functional behavior. The CY2308SXI-1 extends the maximum operating temperature to +105°C but draws higher supply current (up to 75 mA at 100 MHz); no layout or firmware changes are needed for drop-in replacement in thermally benign environments.