Infineon Technologies W134MH

Overview

W134MH from Cypress Semiconductor is a Direct Rambus™ Clock Generator IC that provides differential RSL clock outputs for Rambus memory subsystems, supporting up to 800-MHz data transfer rates. It implements a PLL-based clock synthesis with distributed delay-locked loop (DDLL) phase alignment, accepts REFCLK up to 100 MHz, operates at 3.3 V, and features STOPB and PWRDNB control inputs for dynamic clock gating and power-down in mobile platforms.

For engineers reviewing the W134MH datasheet, W134MH pinout, W134MH application, or W134MH equivalent, this device is selected for Intel architecture platforms requiring precise phase-synchronized Rambus channel clocks, low-jitter timing alignment between Pclk/M and Synclk/N domains, and configurable PLL multiplication ratios (4×–16×) via MULT0/MULT1 pins.

Technical Context

The W134MH integrates a PLL with programmable feedback (A) and prescaler (B) dividers to generate Busclk from REFCLK, enabling gear-ratio-based synchronization between processor (Pclk) and Rambus (Synclk) domains. Its phase detector compares PCLKM and SYNCLKN signals-both derived from M/N-divided clocks-to drive a phase aligner that adjusts Busclk phase until rising edges align within ±50 ps.

It supports four operating modes (Normal, Bypass, Output Test, Test) via S0/S1 pins, includes dedicated voltage references (VDDIR for REFCLK, VDDIPD for phase detector), and delivers Rambus Signaling Level (RSL) complementary outputs (CLK/CLKB) with 40/60% worst-case duty cycle and Hi-Z capability during StopB or PWRDNB assertion.

Key Specifications

Pinout & Package

W134MH is housed in a 24-pin QSOP (150-mil SSOP) package with exposed pad thermal design, pin-compatible with W134M/W134S variants and optimized for high-density Rambus channel routing.

Key Features

Applications

Equivalent & Alternatives

Cypress W134MH has two functionally aligned alternatives with documented compatibility in Intel platform reference designs.

Compared with W134S and W134M, W134MH shares identical packaging, pinout, and mode logic but is distinguished by its specific A/B divider table and qualification for mixed-voltage Intel chipset environments-making it the preferred choice where REFCLK sourcing and gear-ratio constraints demand exact multiplier matching.

Availability

W134MH is available at Aetrix Electronics and suitable for Intel Pentium III desktop platforms, Rambus RDRAM memory subsystems, and mobile Intel architecture notebooks requiring stable component supply and long-term lifecycle support.

Supply support for W134MH 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) is a fabless semiconductor company specializing in timing, memory interface, and programmable logic solutions for computing and communications infrastructure.

The W134MH belongs to Cypress's Direct Rambus Clock Generator product line, engineered specifically to meet Intel's DDLL architecture requirements for phase-aligned, low-jitter clock distribution in RDRAM-based platforms.

FAQ

What is the function of VDDIPD and how must it be connected?

VDDIPD (Pin 10) serves as the voltage reference for the phase detector inputs (PCLKM, SYNCLKN) and STOPB threshold. It must be connected to the same supply rail that powers the memory controller's output drivers-typically 2.5 V or 3.3 V-not the core VDD. Incorrect connection causes phase detection failure or erratic STOPB response due to mismatched input thresholds.

Can W134MH operate without Gear Ratio Logic?

Yes. When Gear Ratio Logic is absent, PCLKM and SYNCLKN must be tied to GND per datasheet guidance. The device then operates in free-running PLL mode using only REFCLK and MULT0/MULT1 settings. Output frequency equals REFCLK × A/B, but phase synchronization to the processor clock is disabled-suitable only for non-synchronous Rambus implementations.

What happens to CLK/CLKB during PWRDNB assertion?

When PWRDNB is driven LOW, the internal PLL shuts down, all logic blocks are powered off, and CLK/CLKB outputs are actively driven to GND (not Hi-Z). This differs from STOPB, which places outputs in high-impedance state. PWRDNB ensures zero static current draw and eliminates any residual clock feedthrough during deep sleep states.

How does the Bypass mode differ from Normal mode in timing behavior?

In Bypass mode (S0=1,S1=0), the full-speed PLL output (PLLclk) appears directly at CLK/CLKB, skipping the phase aligner. This removes DDLL-induced latency but sacrifices phase alignment between Pclk and Synclk domains. Normal mode routes PLLclk through the phase aligner, adding ~2 ns propagation delay but guaranteeing ±50 ps edge alignment critical for zero-latency data transfers.