CY29976AXI

Overview

The CY29976AXI is a 3.3V, 125-MHz multi-output zero-delay buffer manufactured by Infineon Technologies (originally Cypress Semiconductor). It features an integrated PLL with a VCO lock range of 200 MHz to 480 MHz and provides twelve configurable clock outputs across three independent banks (QA, QB, QC). The device accepts PECL or external reference inputs and supports glitch-free frequency transitions. It operates within an industrial temperature range of -40°C to +85°C and is housed in a 52-pin TQFP package.

Feature Summary

• Zero-delay buffering architecture aligns output edges with the input reference edge.
• Twelve configurable clock outputs divided into three independent banks (QA, QB, QC).
• Glitch-free output frequency transitions during dynamic divider changes.
• Supports PECL differential inputs and serial programmable output freeze control.

Applications

• Intel CPU server clock distribution.
• PowerPC processor clock generation.
• Pentium processor system timing.

Procurement Notes

Verify component authenticity as the datasheet notes this part is not recommended for new designs. Confirm package type matches the 52-pin TQFP specification. Ensure supply voltage requirements align with the 3.3V ±10% operating range before procurement.

Selection Notes

Select this component when low-skew clock distribution is required for legacy Intel or PowerPC architectures. Verify that the input clock source supports PECL levels or can be adapted to the specified common mode range. Check if the 12-output configuration meets the system's timing requirements without requiring additional buffers.

Part Context

This component belongs to the CY29976 series of zero-delay buffers. It was originally produced by Cypress Semiconductor Corporation before being acquired by Infineon Technologies. The AXI suffix denotes the industrial temperature grade variant packaged in a 52-pin TQFP.

Replacement Considerations

The SC973X is identified as pin-compatible. Verify electrical parameters and software compatibility before substitution.

FAQ

How does the CY29976 achieve zero delay?

It uses a feedback loop where the FB_OUT output is connected to the FB_IN input. The PLL adjusts the phase to align the output edge with the input reference edge, eliminating propagation delay.

What is the function of the SYNC output?

The SYNC output provides a synchronization pulse for systems where output frequencies are not integer multiples of each other. It generates a pulse prior to the coincident rising edges of QA and QC outputs.

Can individual outputs be disabled?

Yes, through the serial interface using SDATA and SCLK pins. This allows for power management by freezing specific outputs in a logic '0' state.