BCM1122A4KEBG

Overview

The Broadcom BCM1122 is a high-performance system-on-a-chip processor featuring a 400-MHz MIPS64 SB-1 CPU core. It integrates a shared 128-KB L2 cache, DDR memory controller, and extensive I/O interfaces including Gigabit Ethernet, PCI, and serial ports. The architecture utilizes the ZBbus for memory-coherent communication between components. Key specifications include 51-Gbps on-chip bus bandwidth, 13-Gbps memory bandwidth, and 4W power dissipation at full clock speed. Manufactured in a 0.13-µm process, it supports big- or little-endian modes and offers software compatibility with the BCM1125H and BCM1250.

Feature Summary

• MIPS64 SB-1 CPU Core: 400-MHz quad-issue pipeline with dual execute and dual memory pipes, supporting MIPS-3D and MIPS-MDMX ASEs.
• Integrated Memory Controller: Supports DDR SDRAM, SGRAM, and FCRAM via one channel with a 64-bit data bus plus ECC, running at 100 MHz.
• High-Speed Interconnects: Includes one 10/100/1000 Ethernet MAC (configurable as 8-bit FIFO), one 10/100 Ethernet MAC, 66-MHz PCI 2.2 interface, and two serial interfaces up to T3/OC-1 rates.
• Shared L2 Cache: 128-KB four-way associative cache protected by ECC, connected via the 256-bit ZBbus operating at half the CPU clock rate.

Applications

• Networking equipment such as routers and switches
• Control plane processing and line cards
• Broadband access systems including DSLAM, CMTS, and BRAS
• Wireless base stations
• Storage controllers such as RAID, NAS, and HBAs

Procurement Notes

Verify the specific package marking and revision code against the official datasheet to ensure authenticity. Confirm that the silicon revision matches the intended software support requirements, particularly regarding OS compatibility with VxWorks, Linux, NetBSD, QNX, or OSE. Ensure the procurement source provides valid traceability documentation for this legacy component.

Selection Notes

Select the BCM1122 when software compatibility with the BCM1125H or BCM1250 is required for existing codebases. Consider this processor for applications needing integrated Gigabit Ethernet and PCI interfaces without external bridge chips. Evaluate the 4W power consumption against thermal constraints. Verify that the target application can utilize the 128-KB shared L2 cache effectively for latency-sensitive operations.

Part Context

The BCM1122 belongs to Broadcom's networking processor family, designed for next-generation infrastructure applications. It shares development tools, firmware, and operating systems with the BCM1125H and BCM1250. The chip is manufactured using a TSMC 0.13-µm process and is housed in a pin-compatible 31-mm BGA package, facilitating potential design upgrades within compatible form factors.

Replacement Considerations

The BCM1122 is software-compatible with the BCM1125H and BCM1250. These parts share the same ISA and toolchain support. Verify pin compatibility if substituting directly into existing hardware designs, noting that the BCM1122 is pin-compatible with the BCM1125H.