NXP Semiconductors KMC7457RX1267LC

Overview

KMC7457RX1267LC from Freescale Semiconductor is a 32-bit PowerPC G4 RISC microprocessor with a 1.3 V core supply, 512-Kbyte on-chip L2 cache, and dedicated glueless L3 cache interface supporting up to 4 Mbytes of external SRAM. It features a superscalar 7-stage pipeline, AltiVec™ SIMD unit, double-precision IEEE 754 FPU, and is designed for high-performance networking and computing systems requiring deterministic real-time processing.

For engineers reviewing the KMC7457RX1267LC datasheet, KMC7457RX1267LC pinout, KMC7457RX1267LC application, or KMC7457RX1267LC equivalent, this page delivers verified electrical specs (1.3 V core, 1.5/1.8/2.5 V I/O options), thermal resistance (RθJA = 20°C/W), L3 interface bandwidth (64-bit, configurable divisors), and confirmed drop-in compatibility with MPC7455 in 1.3 V core designs - critical for legacy system upgrades and embedded compute platform continuity.

Technical Context

The KMC7457RX1267LC implements a fully static 0.13 μm CMOS design with 58 million transistors and a 9.1 mm × 10.8 mm die. Its Harvard L1 architecture includes separate 32-Kbyte 8-way set associative instruction and data caches, each supporting parity, lockable ways, and critical-word forwarding.

It integrates dual MMUs with 128-entry 2-way TLBs, hardware-enforced MESI coherency, and an L3 controller supporting MSUG2 DDR, PB2, and late-write synchronous burst SRAMs. The processor supports three power-saving modes (Nap, Sleep, Deep Sleep) and includes JTAG/COP debug, performance monitoring, and thermal management registers.

Key Specifications

Pinout & Package

Package: Surface-mount 483-ball ceramic ball grid array (CBGA), RoHS-compliant, 35 mm × 35 mm footprint, 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPC7455EC and MPC7447EC, the KMC7457RX1267LC uniquely delivers 512-Kbyte L2 + configurable L3 SRAM expansion, enabling higher sustained bandwidth for packet buffering and real-time analytics - making it the only option among the three for systems requiring >256 KB on-die cache plus scalable off-die memory.

Availability

KMC7457RX1267LC is available at Aetrix Electronics and suitable for network router control planes, industrial real-time controllers, legacy workstation upgrades, and secure communications gateways requiring stable component supply across extended product lifecycles.

Supply support for KMC7457RX1267LC 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) is a fabless semiconductor company specializing in embedded processing, connectivity, and analog solutions for automotive, industrial, and networking markets.

The MPC7457 product line was engineered for high-performance embedded computing applications demanding deterministic real-time execution, hardware-accelerated multimedia processing, and long-term industrial availability - targeting telecom infrastructure and mission-critical control systems.

FAQ

What is the core supply voltage requirement for KMC7457RX1267LC?

The KMC7457RX1267LC requires a tightly regulated 1.3 V ±50 mV DC core supply (VDD). This voltage powers the 58-million-transistor die and must be delivered through at least 10 dedicated VDD balls with local 100 nF + 10 μF decoupling. Deviation beyond ±50 mV risks timing violations in the 7-stage pipeline or FPU functional errors. The KMC7457RX1267LC datasheet specifies this as the absolute operating condition - not a recommendation - for guaranteed operation at rated frequency.

Does KMC7457RX1267LC support pin-compatible replacement of MPC7455 in existing designs?

Yes, the KMC7457RX1267LC is a footprint-compatible, drop-in replacement for MPC7455 in applications using a 1.3 V core supply. Both use identical 483-ball CBGA packages and share the same pinout, voltage thresholds, and reset sequencing. However, the KMC7457RX1267LC's enhanced 512-Kbyte L2 cache and L3 interface require no PCB changes but may need minor BIOS/firmware updates to initialize new cache control registers and L3 configuration bits.

What L3 SRAM configurations does KMC7457RX1267LC support?

The KMC7457RX1267LC supports 1 MB, 2 MB, or 4 MB total external SRAM space via its L3 interface, with up to 2 MB usable as cache and the remainder as private memory. It interfaces with MSUG2 DDR, PB2 pipelined, and late-write synchronous burst SRAMs using a 64-bit data bus. Line sizes are 64 bytes (1 MB config) or 128 bytes (2 MB config); the KMC7457RX1267LC's L3CR register controls write-back/write-through policy per page.

How does thermal management operate in KMC7457RX1267LC?

KMC7457RX1267LC implements thermal management via three supervisor-level registers (THRM1–THRM3) and a dedicated thermal management exception. Software can read die temperature, configure trip points, and trigger instruction cache throttling to reduce power. The KMC7457RX1267LC's RθJA of 20°C/W means a 10 W load raises junction temperature 200°C above ambient - so active cooling or derating is required above 5 W in sealed enclosures to stay within the 105°C max Tj limit.

Is KMC7457RX1267LC compatible with 1.5 V L3 interface signaling?

Yes, the KMC7457RX1267LC supports 1.5 V L3 I/O signaling when L3VSEL is driven to ¬HRESET (inverse of HRESET) at reset negation, configuring GVDD to 1.5 V ±5%. This mode enables direct interfacing with low-voltage MSUG2 DDR SRAMs without level shifters. The KMC7457RX1267LC's input threshold is set dynamically at boot, and GVDD must remain stable within ±5% during operation to prevent setup/hold violations on L3 address/data lines.