Renesas IDT79RV4640-267DU

Overview

IDT79RV4640-267DU from Integrated Device Technology is a 3.3V, 267 MHz, 64-bit MIPS-III RISC microprocessor with integrated floating-point coprocessor, 8KB instruction cache, and 8KB data cache. It delivers 352 Dhrystone MIPS, 89 MFLOPS single-precision performance, and 133.5 M multiply-accumulate operations/sec for embedded control and DSP-intensive applications such as network routers and multimedia game systems.

For engineers reviewing the IDT79RV4640-267DU datasheet, IDT79RV4640-267DU pinout, IDT79RV4640-267DU application, or IDT79RV4640-267DU equivalent, key selection criteria include its 267 MHz pipeline clock, 32-bit synchronized system bus interface, on-chip cache locking support, and software compatibility with IDT RC4000 and RC32300 families.

Technical Context

The IDT79RV4640-267DU implements a 5-stage integer pipeline with autonomous multiply/divide unit and dedicated floating-point execution units for IEEE 754 single-precision arithmetic. Its CP0 system control coprocessor provides base-bounds virtual memory management without TLB, real-time cycle counting, and interrupt vector acceleration.

It features two-way set-associative caches (8KB I-cache, 8KB D-cache), write-back/write-through policies controlled via CP0 CAlg register, and a 32-bit multiplexed SysAD bus with 8-bit parity, synchronized to external reference clock (50–125 MHz) and internally multiplied to 267 MHz via on-chip PLL.

Key Specifications

Pinout & Package

The IDT79RV4640-267DU is housed in a 256-pin Ceramic Pin Grid Array (CPGA) package with 1.27 mm pitch, compatible with socket mounting per IDT RC64474/RC64574 mechanical specifications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 64-bit embedded RISC processor applications.

Compared with IDT79RV4640-267DU, the 5V IDT79RC4640-267DU offers identical performance at higher power cost, while IDT79RC4650-267DU extends functionality with double-precision FP and debug enhancements - making it suitable for applications demanding higher numerical precision or deeper system visibility.

Availability

IDT79RV4640-267DU is available at Aetrix Electronics and suitable for network infrastructure, industrial protocol gateways, and embedded multimedia systems requiring stable component supply across extended production lifecycles.

Supply support for IDT79RV4640-267DU 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

Integrated Device Technology, Inc. (IDT) was a fabless semiconductor company specializing in timing, memory interface, RF, and high-performance embedded processors before its acquisition by Renesas Electronics in 2019.

The IDT79RV4640-267DU belongs to the RC4000 family of low-cost, high-integration 64-bit RISC controllers designed for performance-hungry embedded applications including internetworking, office automation, and consumer multimedia.

FAQ

What is the operating voltage specification for the IDT79RV4640-267DU?

The IDT79RV4640-267DU operates at a nominal 3.3V supply for both core and I/O circuits. The "RV" prefix explicitly denotes the 3.3V variant within IDT's RC4640 product line, distinguishing it from the 5V "RC" and mixed-voltage "R" versions. This voltage level reduces power consumption and thermal output compared to 5V alternatives while maintaining full 267 MHz operation under specified temperature and load conditions. The IDT79RV4640-267DU requires clean, well-decoupled 3.3V rails per IDT's hardware design guidelines.

Does the IDT79RV4640-267DU support double-precision floating-point operations?

No, the IDT79RV4640-267DU does not implement double-precision floating-point operations in hardware. Its on-chip floating-point coprocessor supports only IEEE 754 single-precision arithmetic. Attempts to execute double-precision instructions trigger a trap to the integer unit, enabling software emulation. This design choice reduces die area and power while preserving binary compatibility with higher-end IDT processors like the RC4700. The IDT79RV4640-267DU achieves 89 MFLOPS using single-precision only.

How does cache locking function on the IDT79RV4640-267DU?

Cache locking on the IDT79RV4640-267DU applies exclusively to Set A of both the 8KB instruction and 8KB data caches. A bit in the CP0 Config register enables locking, which prevents cache line replacement in Set A during subsequent misses - ensuring time-critical code or data remains resident. This guarantees deterministic access latency for real-time tasks. Set B remains fully associative and dynamic. The IDT79RV4640-267DU uses this feature to isolate interrupt service routines and control loops from cache thrashing caused by background processes.

Is the IDT79RV4640-267DU pin-compatible with other IDT processors?

Yes, the IDT79RV4640-267DU is socket-compatible with IDT RC64474 and RC64574 processors, sharing identical 256-pin CPGA mechanical dimensions and pinout. It is also bus-compatible with the RC4000 family and upwardly software-compatible with the RC32300 family. However, it is not pin-compatible with the RC4650 - though the RC4650 offers a direct migration path via full pin and socket compatibility, meaning PCB layout reuse is possible only with appropriate redesign for the RC4650's enhanced signal requirements. The IDT79RV4640-267DU maintains backward compatibility at the socket level for legacy RC64474/RC64574 designs.

What boot-time configuration options are available for the IDT79RV4640-267DU?

Boot-time configuration for the IDT79RV4640-267DU is controlled via a 256-bit serial mode stream loaded immediately after VCCOK assertion, operating at MasterClock/256 frequency. This interface initializes fundamental modes including PLL multiplier (2× to 8×), cache write policy, bus timing parameters, and exception vector mapping. Configuration bits are typically stored in low-cost EPROM or generated by system ASIC. Unlike later IDT processors, the IDT79RV4640-267DU does not support JTAG-based runtime reconfiguration; all operational modes are fixed at power-on reset based on this serial stream.