Infineon Technologies CY29976AI

Overview

CY29976AI from Cypress Semiconductor is a 3.3V, 125-MHz multi-output zero-delay buffer 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® processor clock trees for memory interface timing and system-level synchronization.

For engineers reviewing the CY29976AI datasheet, CY29976AI pinout, CY29976AI application, or CY29976AI equivalent, key selection considerations include VCO lock range (200–480 MHz), glitch-free on-the-fly frequency transitions via SELA/SELB/SELC, PECL/LVPECL reference compatibility, industrial temperature operation (–40°C to +85°C), and 52-pin TQFP package layout.

Technical Context

The CY29976AI implements a phase-locked loop with programmable VCO divider (×4 to ×20) and bank-specific post-dividers (÷2 to ÷24), enabling precise output frequency synthesis up to 125 MHz while maintaining static phase alignment between input reference and outputs. Its dual-reference architecture supports dynamic toggling between PECL_CLK/PECL_CLK# and TCLK0/TCLK1 inputs via REF_SEL and TCLK_SEL.

Glitch-free transitions are guaranteed during real-time reconfiguration of SELA(1:0), SELB(1:0), SELC(1:0), and VCO_SEL pins; the SYNC output provides a deterministic one-cycle pulse aligned to coincident rising edges of QA and QC banks - critical for multi-frequency domain synchronization in high-speed microprocessor systems.

Key Specifications

Pinout & Package

The CY29976AI is housed in a 52-pin Thin Quad Flat Pack (TQFP) with exposed thermal pad (A52 package), requiring strict adherence to 0.1 µF bypass capacitor placement within 0.2" of each VDD/VDDC pin to preserve high-frequency noise immunity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72V223L and ICS853S01I, the CY29976AI uniquely combines 12 configurable outputs, PECL reference support, hardware SYNC generation, and true zero-delay operation - making it irreplaceable in legacy PowerPC/Pentium clock tree upgrades where timing fidelity and backward pin compatibility (vs. SC973X) are mandatory.

Availability

CY29976AI is available at Aetrix Electronics and suitable for PowerPC processor clock trees, Pentium front-side bus timing, and DDR SDRAM memory interface designs requiring stable component supply under industrial temperature conditions.

Supply support for CY29976AI 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, and microcontroller solutions for industrial, automotive, and computing markets.

The CY29976AI belongs to Cypress's legacy zero-delay buffer product line, designed specifically to replace discrete clock distribution networks in high-performance microprocessor systems with integrated PLL-based timing consolidation.

FAQ

What is the function of the FB_OUT and FB_IN pins?

FB_OUT is the PLL feedback clock output whose divider ratio is set by FB_SEL(2:0); FB_IN is the dedicated input that must be connected to FB_OUT to close the PLL loop. This feedback path enables the device to achieve zero-delay operation by aligning output edges with the reference input edge. The VCO frequency is derived from this loop and then divided down to generate all output clocks.

Can the CY29976AI operate with a single-ended reference clock?

No - the CY29976AI requires either a differential PECL reference (PECL_CLK/PECL_CLK#) or a single-ended TTL/CMOS-compatible reference applied to TCLK0 or TCLK1. The PECL input has strict common-mode voltage requirements (VDD–2.0 V to VDD–0.6 V), while TCLK inputs accept standard 3.3V logic levels. REF_SEL selects between these two reference sources.

How does the SYNC output behave when QA and QC banks run at non-integer frequency ratios?

The SYNC output generates a one-cycle low-going pulse precisely one period before the next coincident rising edge of any QA and QC output pair - regardless of their frequency ratio (e.g., 3:2, 4:3). Its timing is determined solely by the higher-frequency bank, ensuring deterministic alignment even in asynchronous multi-domain systems without requiring external logic.

Is the CY29976AI suitable for new designs?

No - Cypress explicitly marks CY29976AI as "Not Recommended for New Designs" (Note 13, Page 7). It remains available for legacy system repair and continuity, but Infineon recommends migrating to newer timing solutions such as the XNP series or TruEdge™ family for enhanced features, extended temperature support, and active lifecycle management.