NXP Semiconductors KMC7457VG1267LC

Overview

KMC7457VG1267LC from Freescale Semiconductor is a 1.3 V core, 512-Kbyte L2 cache, PowerPC G4 RISC microprocessor with integrated L3 cache controller, 32-Kbyte L1 instruction and data caches, and AltiVec™ vector processing unit. It targets high-performance networking and computing systems requiring glueless backside L3 SRAM expansion, IEEE 754-1985-compliant floating-point execution, and hardware-enforced MESI coherency.

For engineers reviewing the KMC7457VG1267LC datasheet, KMC7457VG1267LC pinout, KMC7457VG1267LC application, or KMC7457VG1267LC equivalent, this page delivers verified electrical specs (1.3 V ±50 mV core, 1.5/1.8/2.5 V I/O options), thermal resistance (RθJA = 20°C/W), L3 interface support (1–4 MB SRAM), superscalar dispatch (3 instructions/cycle), and 7-stage pipeline timing - all confirmed from Freescale Rev. 8 hardware specification.

Technical Context

The KMC7457VG1267LC implements a fully static, 0.13 μm CMOS, 58-million-transistor superscalar core with eleven independent execution units: four integer units (IU1a/b/c, IU2), five-stage FPU, four vector units (VIU1/VIU2/VFPU/VPU), and three-issue queues (FIQ/VIQ/GIQ). Its Harvard L1 cache subsystem features 32-Kbyte 8-way set associative instruction and data caches with PLRU replacement, critical double-word forwarding, and hardware MESI coherency.

It integrates a dedicated 512-Kbyte unified L2 cache with 256-bit pipelined interface (9-cycle L1 miss latency), an on-die L3 cache controller supporting 1–4 MB external SRAM (64-/128-byte line sizes), dual MMUs with 128-entry 2-way TLBs, and JTAG/COP debug infrastructure. Core-to-L3 frequency divisors and configurable write-back/write-through policies per page/block are supported.

Key Specifications

Pinout & Package

Package: 483-ball ceramic ball grid array (CBGA), surface-mount, 9.1 mm × 10.8 mm die size, 6.8 ppm/°C CTE.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RISC microprocessor applications.

Compared with MPC7455EC and MPC7447EC, the KMC7457VG1267LC uniquely delivers 512-Kbyte L2 + L3 controller in a single package - enabling higher memory bandwidth density and eliminating glue logic for SRAM-based cache expansion, critical for throughput-bound router control planes and scientific instruments.

Availability

KMC7457VG1267LC is available at Aetrix Electronics and suitable for network router control planes, high-end print servers, scientific data acquisition systems, legacy industrial HMIs, and embedded computing platforms requiring stable component supply across extended product lifecycles.

Supply support for KMC7457VG1267LC 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

Freescale Semiconductor (now part of NXP Semiconductors) designed high-performance PowerPC processors for embedded networking, automotive, and industrial applications before its 2015 acquisition.

The MPC7457 product line was engineered for demanding computing systems requiring AltiVec acceleration, large on-die caches, and scalable L3 expansion - targeting telecom infrastructure, test equipment, and real-time control where deterministic performance and thermal efficiency are critical.

FAQ

What is the core supply voltage requirement for KMC7457VG1267LC?

The KMC7457VG1267LC requires a nominal 1.3 V ±50 mV DC core supply (VDD) under all operating conditions. This voltage must be maintained within tolerance during active operation and transitions; deviation beyond ±50 mV risks timing violations or functional failure. The specification explicitly states that VDD must not exceed OVDD/GVDD by more than 1.0 V during normal operation, and that AVDD (PLL supply) shares the same 1.3 V ±50 mV requirement.

Does KMC7457VG1267LC support L3 cache expansion, and what SRAM types are compatible?

Yes, the KMC7457VG1267LC includes an integrated L3 cache controller supporting 1 MB, 2 MB, or 4 MB of external SRAM. It is compatible with MSUG2 DDR synchronous burst SRAMs, PB2 pipelined synchronous burst SRAMs, and pipelined late-write (LW) synchronous burst SRAMs. The L3 interface uses a 64-bit data bus and supports programmable write-back/write-through policies per page or block, with 64-byte (1 MB) or 128-byte (2 MB) line sizes.

What are the thermal resistance values for KMC7457VG1267LC in natural convection?

The KMC7457VG1267LC has a junction-to-ambient thermal resistance (RθJA) of 20°C/W under natural convection conditions, as specified in Table 5 of the Rev. 8 hardware specification. This value assumes standard mounting on a typical PCB; it drops to 14°C/W on a four-layer board and 15°C/W with 200 ft/min airflow on a single-layer board. These figures directly determine maximum allowable power dissipation for safe junction temperature (≤105°C).

How does the branch prediction unit in KMC7457VG1267LC improve performance?

The KMC7457VG1267LC implements a branch prediction unit with a 128-entry, 4-way set associative branch target instruction cache (BTIC) and a 2048-entry, 2-bit branch history table (BHT). This configuration reduces the misprediction penalty to 6 cycles and enables 1-cycle latency for taken branches on BTIC hits. The unit also supports up to three outstanding speculative branches and an 8-entry link register stack for bclr prediction - collectively minimizing pipeline stalls in loop- and branch-heavy code.

Is KMC7457VG1267LC pin-compatible with earlier MPC74xx processors?

The KMC7457VG1267LC uses a 483-ball CBGA package, which differs from the 360-ball CBGA used by the MPC7447. While the MPC7457 is described as "footprint-compatible, drop-in replacement in a MPC7455 application" when the core supply is 1.3 V, this refers to functional and electrical compatibility-not mechanical pinout identity. Physical pin mapping differs between 360-ball and 483-ball packages; PCB layout changes are required for migration from MPC7447 or MPC7455 to KMC7457VG1267LC.