Renesas 7008S55PFI8

Overview

7008S55PFI8 from IDT (Integrated Device Technology) is a high-speed 64K × 8 true dual-port static RAM with independent left/right ports, 55 ns maximum access time, TTL-compatible 5V ±10% operation, and integrated semaphore/arbitration logic for inter-processor communication in real-time embedded systems.

For engineers reviewing the 7008S55PFI8 datasheet, 7008S55PFI8 pinout, 7008S55PFI8 application, or 7008S55PFI8 equivalent, this device supports simultaneous asynchronous read/write access to shared memory, hardware BUSY flag arbitration, interrupt signaling via FFFE/FFFF mailbox addresses, and low-power standby modes - critical for multi-CPU control, digital signal processing, and industrial motion controllers.

Technical Context

The 7008S55PFI8 implements fully asynchronous dual-port architecture with separate address, data, and control buses per port (A0L–A15L/I/O0L–I/O7L/R/WL/CE0L/CE1L/OEL/SEML/INTL/BUSYL on left; mirrored on right), enabling concurrent memory access without clock synchronization. Its on-chip arbitration logic resolves contention via BUSY flag assertion (push-pull output) when address matches occur across ports.

It supports semaphore signaling using dedicated A0–A2-addressed flags (8 total), accessed via CE = VIH and SEM = VIL, and interrupt generation by writing to fixed mailbox addresses (FFFE_H for INTL, FFFF_H for INTR). The M/S pin configures master (BUSY output) or slave (BUSY input) behavior in cascaded systems.

Key Specifications

Pinout & Package

7008S55PFI8 is housed in a 100-pin Thin Quad Flatpack (TQFP) package (package code PNG100), measuring approximately 14 mm × 14 mm × 1.4 mm, with exposed pad for thermal dissipation and standard 0.5 mm pitch leads.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-port SRAM applications.

Compared with CY7C136-55JC and AS7C3616A-55PCN, the 7008S55PFI8 uniquely integrates hardware semaphore, BUSY arbitration, and M/S cascading in a 5V 100-pin TQFP package - making it the sole option for deterministic, low-latency inter-processor communication in industrial 5V systems without added logic.

Availability

7008S55PFI8 is available at Aetrix Electronics and suitable for industrial motion controllers, redundant communication gateways, and multi-core test equipment requiring stable component supply, long-term lifecycle support, and guaranteed 55 ns performance across –40°C to +85°C.

Supply support for 7008S55PFI8 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

IDT (Integrated Device Technology) is a fabless semiconductor company specializing in high-performance timing, memory, and interface solutions for communications, computing, and industrial markets.

The IDT7008 product line was designed specifically for real-time embedded systems requiring deterministic, hardware-managed inter-processor communication - delivering true dual-port SRAM with integrated arbitration, semaphore, and interrupt capabilities in a single 5V device.

FAQ

What is the maximum operating temperature range supported by the 7008S55PFI8?

The 7008S55PFI8 is rated for industrial temperature operation from –40°C to +85°C. This specification is confirmed in the "Maximum Operating Temperature and Supply Voltage" table (Table 7) and applies to all speed grades including the 55 ns version. It ensures reliable operation in harsh environments such as factory automation controllers and outdoor telecom equipment where ambient temperatures exceed commercial limits.

Does the 7008S55PFI8 support true simultaneous read operations on both ports to the same memory address?

Yes, the 7008S55PFI8 uses true dual-ported memory cells that permit simultaneous reads from the same location on both left and right ports without contention or delay. This capability is explicitly stated in the "Features" section ("True Dual-Ported memory cells which allow simultaneous reads of the same memory location") and is fundamental to its architecture - unlike pseudo-dual-port or pipelined SRAMs that serialize concurrent accesses.

How does the BUSY arbitration logic function when the 7008S55PFI8 is configured as a Master versus a Slave?

When M/S = VIH (Master), BUSYL and BUSYR are push-pull outputs that assert LOW to block writes during address contention. When M/S = VIL (Slave), BUSYL and BUSYR become inputs - a LOW signal from the master inhibits writes on the slave port. This behavior is defined in Note 1 of the Functional Block Diagram and Truth Table V, ensuring deterministic resolution of port-to-port conflicts in cascaded configurations.

What are the exact mailbox addresses used for interrupt generation in the 7008S55PFI8?

The 7008S55PFI8 uses fixed hexadecimal addresses FFFE_H and FFFF_H for interrupt signaling: writing to FFFE_H from the right port asserts INTL, and writing to FFFF_H from the left port asserts INTR. These addresses are reserved for mailbox functionality and documented in the "Functional Description" section and Truth Table IV - they are not general-purpose memory locations when interrupts are enabled.

Is the 7008S55PFI8 pin-compatible with other members of the IDT7008 family, such as the 7008S25PFI8?

Yes, all IDT7008 variants - including 7008S15, 7008S25, 7008S35, 7008S55, and their L-power counterparts - share identical pinouts across the same package type (e.g., 100-pin TQFP). The 7008S55PFI8 uses the PNG100 footprint, and mechanical compatibility is confirmed in Pin Configuration drawings (drw 03) and the "Pin Names" table - allowing drop-in replacement for timing upgrades without PCB revision.