Infineon Technologies CY29976AXI

Overview

CY29976AXI from Cypress Semiconductor is a 3.3V, 125-MHz multi-output zero-delay buffer IC with integrated PLL, delivering 12 low-skew clock outputs across three independent banks (QA0–QA3, QB0–QB3, QC0–QC3), FB_OUT feedback output, and SYNC synchronization pulse - used in PowerPC® and Pentium®-based high-performance computing systems requiring precise clock distribution and glitch-free frequency transitions.

For engineers reviewing the CY29976AXI datasheet, CY29976AXI pinout, CY29976AXI application, or CY29976AXI equivalent, key selection considerations include VCO lock range (200–480 MHz), output skew ≤350 ps (same-frequency), configurable divider ratios per bank, PECL/LVPECL reference compatibility, and industrial temperature operation (–40°C to +85°C).

Technical Context

The CY29976AXI implements a phase-locked loop with voltage-controlled oscillator operating between 200 MHz and 480 MHz, supporting integer division via FB_SEL(0:2) and VCO_SEL to generate stable output frequencies up to 125 MHz. Its PLL architecture enables zero-delay buffering by feeding FB_OUT back to FB_IN, aligning output edges with input reference edges.

Three independent output banks (QA, QB, QC) each support four programmable dividers controlled by SELA/SELB/SELC(1:0), while INV_CLK enables inversion of QC2/QC3 for early/late clock generation. Glitch-free on-the-fly reconfiguration is guaranteed for SELA/SELB/SELC/VCO_SEL changes without runt or stretched cycles.

Key Specifications

Pinout & Package

52-pin TQFP (A52 package, 10×10×1.4 mm), lead-free, industrial temperature grade (–40°C to +85°C). Requires 0.1 µF bypass capacitors within 0.2" of each VDDC and VDD pin.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multi-output zero-delay buffer applications.

Compared with IDT5V9885BGI and ICS85304AGI, the CY29976AXI uniquely combines 12 configurable outputs, native PECL input, hardware-guaranteed glitch-free transitions, and dedicated SYNC pulse - making it optimal for PowerPC/Pentium clock trees demanding inter-bank determinism and legacy compatibility.

Availability

CY29976AXI is available at Aetrix Electronics and suitable for PowerPC® system clock distribution, Pentium®-based workstation timing, multi-FPGA synchronization platforms, and legacy embedded controller timing requiring stable component supply across industrial temperature ranges.

Supply support for CY29976AXI 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 programmable logic solutions for computing, communications, and industrial applications.

The CY29976AXI belongs to Cypress's Zero-Delay Buffer product line, engineered specifically for low-skew, multi-output clock distribution in high-speed microprocessor systems with stringent jitter and phase alignment requirements.

FAQ

What is the minimum reference clock frequency supported by CY29976AXI?

The minimum reference frequency is constrained by the VCO lock range (200–480 MHz) and FB_SEL/VCO_SEL divider settings. For example, with FB_SEL=000 (8×) and VCO_SEL=0 (÷2), minimum reference is 200 MHz ÷ 8 ÷ 2 = 12.5 MHz. Actual usable minimum depends on selected output divider; datasheet specifies FrefDC duty cycle must be 25–75%.

Can CY29976AXI operate without connecting FB_OUT to FB_IN?

No - FB_OUT must be connected to FB_IN for normal PLL operation and zero-delay functionality. Open-loop operation (bypassing PLL via PLL_EN=LOW) disables the VCO and routes reference directly to outputs with added propagation delay and no phase alignment; this mode sacrifices jitter performance and skew control.

How does the SYNC output behave when QA and QC frequencies are non-integer-related?

SYNC generates a one-cycle low pulse placed one period before coincident rising edges of QA and QC outputs, regardless of integer or non-integer frequency ratios. Pulse placement and duration scale with the higher of the two frequencies; timing is deterministic and hardware-generated without software intervention.

Is CY29976AXI compatible with modern 1.8V or 2.5V logic interfaces?

No - CY29976AXI is strictly a 3.3V device: VDD and VDDC require 3.3V ±10%, and all I/O thresholds (VIH=2.0V, VIL=0.8V) are defined relative to that supply. It drives 3.3V CMOS/LVCMOS loads and accepts 3.3V-compatible inputs; level-shifting is required for interfacing with 1.8V/2.5V systems.