Infineon Technologies W40S01-04H

Overview

The W40S01-04 from Cypress Semiconductor Corporation is an 18-output SDRAM clock buffer designed for four-DIMM memory subsystems in Intel 440BX-based platforms. It delivers rail-to-rail CMOS outputs with 15Ω typical output impedance, ±250 ps output skew, and 1–5 ns propagation delay across a DC–133 MHz range on a single 3.3V supply.

For engineers reviewing the W40S01-04 datasheet, W40S01-04 pinout, W40S01-04 application, or W40S01-04 equivalent, key selection criteria include SMBus-configurable output enable per channel, tristate control via OE or serial interface, tight skew tolerance for synchronous DIMM clocking, and compatibility with TTL/CMOS logic levels under capacitive load conditions.

Technical Context

The W40S01-04 implements a dedicated low-skew clock distribution architecture for SDRAM DIMM fanout, with all 18 outputs phase-aligned to BUF_IN and internally matched within ±250 ps. Its output drivers are rail-to-rail CMOS with 15Ω nominal impedance, optimized for driving 60Ω transmission lines terminated with 20 pF loads.

Configuration is performed via a two-wire SMBus interface (SCLOCK/SDATA) using a fixed slave address (11010010), supporting per-output enable/disable through three serial data bytes. OE pin provides hardware-level tristate control with internal 250 kΩ pull-up.

Key Specifications

Pinout & Package

Package: 48-pin SSOP (Small Shrink Outline Package), 0.635 mm pitch, body size 10.2 × 12.8 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar SDRAM clock buffer applications.

Compared with IDT 74FCT162244ATPA and ON Semi NB3N502DG, the W40S01-04 uniquely combines 18-channel fanout, ±250 ps skew, SMBus configurability, and 15 Ω output impedance-making it the only solution validated for four-DIMM Intel 440BX memory subsystems requiring both timing precision and runtime flexibility.

Availability

W40S01-04 is available at Aetrix Electronics and suitable for desktop motherboards, workstation memory controllers, industrial embedded SBCs, and legacy server riser cards requiring stable component supply and long-term obsolescence support.

Supply support for W40S01-04 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 Corporation, now part of Infineon Technologies, is a fabless semiconductor company specializing in memory, clock, and interface solutions for computing and industrial systems.

The W40S01-04 belongs to Cypress's clock buffer product line, engineered specifically for high-density SDRAM memory subsystems in x86-based platforms requiring precise skew control and flexible configuration.

FAQ

What is the function of the NC pins on the W40S01-04?

Pins 1, 2, 47, and 48 are No Connect (NC) terminals with no internal connection. They must remain unconnected in PCB layout to avoid parasitic coupling or mechanical interference. These pins exist solely for package symmetry and thermal relief; routing or stitching them to ground or power violates the device's electrical specification and may degrade output skew performance.

Can the W40S01-04 operate with a 2.5V supply?

No. The W40S01-04 is specified exclusively for 3.3V ±5% operation (3.135–3.465 V). Its output drivers, input thresholds, and internal logic are characterized only at this voltage. Applying 2.5V will result in undefined behavior, including failure to recognize logic-high inputs, degraded output swing, and potential violation of setup/hold timing at SDRAM inputs.

How does the SMBus interface interact with the OE pin?

The OE pin and SMBus interface operate independently but concurrently: OE provides global hardware tristate control, while SMBus enables per-output enable/disable. When OE = LOW, all outputs are forced high-impedance regardless of SMBus register state. When OE = HIGH, output states follow SMBus configuration. This hierarchy ensures fail-safe clock disable during system reset or fault conditions.

Is the W40S01-04 compliant with JEDEC SDRAM timing specifications?

Yes. With its 1–5 ns propagation delay, ±250 ps output skew, and rail-to-rail 3.3V output swing into 20 pF loads, the W40S01-04 meets JEDEC PC100 and PC133 SDRAM clock timing requirements-including t_SKO, t_DSH, and t_DSL-when used with proper 60 Ω trace routing and decoupling per Cypress Application Note AN-447.