Renesas 70V26S55J8

Overview

70V26S55J8 from Integrated Device Technology is a high-speed 3.3V 16K × 16 true dual-port static RAM with 55 ns maximum access time, TTL-compatible I/O, and on-chip semaphore logic for inter-processor resource coordination. It supports independent asynchronous read/write operations on left and right ports, operates over commercial temperature range (0°C to +70°C), and features separate upper/lower byte enables for multiplexed bus compatibility - used in real-time embedded control systems requiring deterministic memory arbitration.

For engineers reviewing the 70V26S55J8 datasheet, 70V26S55J8 pinout, 70V26S55J8 application, or 70V26S55J8 equivalent, key selection criteria include BUSY arbitration timing (tBDD ≤ 50 ns), dual-port power-down current (ISB3 = 1.0 mA typ.), and 84-pin PLCC package compatibility with legacy industrial controller backplanes.

Technical Context

The 70V26S55J8 implements fully asynchronous dual-port architecture with independent address, control, and data buses per port. Its on-chip arbitration logic resolves simultaneous access conflicts via push-pull BUSY outputs (BUSYL/BUSYR), while dedicated semaphore latches (8 flags, addressed by A0–A2) enable hardware-assisted token passing without software wait states.

It uses CMOS high-performance fabrication for 300 mW typical active power at 3.3 V ±0.3 V supply, with automatic CE-controlled standby mode. The device supports MASTER/SLAVE cascading for 32-bit+ word expansion, where M/S pin configures BUSY as output (master) or input (slave), enabling scalable multi-processor memory subsystems.

Key Specifications

Pinout & Package

70V26S55J8 is housed in an 84-pin Plastic Leaded Chip Carrier (PLCC) with 1.15 in × 1.15 in body size and J-lead configuration. All VDD pins require local decoupling; all VSS pins must be connected to ground plane for signal integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C026V-55AXC, 70V26S55J8 integrates arbitration and semaphores, reducing system complexity; compared with IDT70V27L25PF, it trades speed and temperature range for pin-compatible upgrade path and lower cost in commercial-grade systems.

Availability

70V26S55J8 is available at Aetrix Electronics and suitable for industrial PLC memory buffers, real-time motion controllers, and test equipment pattern memory requiring stable component supply across long production lifecycles.

Supply support for 70V26S55J8 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 (IDT), now part of Renesas Electronics, specialized in high-performance timing, memory, and interface ICs for communications and computing infrastructure.

The 70V26S55J8 belongs to IDT's legacy dual-port SRAM product line, designed specifically for deterministic multi-processor memory sharing in real-time embedded systems where hardware arbitration eliminates software-induced latency.

FAQ

What is the maximum operating frequency supported by the 70V26S55J8?

The 70V26S55J8 does not specify a maximum clock frequency because it is an asynchronous SRAM. Its performance is defined by access timing parameters: tRC (read cycle time) is 55 ns maximum, enabling effective operation up to approximately 18.2 MHz in systems with zero wait states and ideal timing margins. Actual system throughput depends on controller interface design and bus protocol overhead.

Does the 70V26S55J8 support both master and slave configurations on the same PCB?

Yes, the 70V26S55J8 supports configurable master/slave operation via the M/S pin. When M/S = VIH, BUSYL and BUSYR function as push-pull outputs for arbitration signaling; when M/S = VIL, they become inputs for write inhibition. Multiple 70V26S55J8 devices can coexist on one board - one configured as master, others as slaves - enabling scalable 32-bit+ memory expansion without external logic.

How do the semaphore flags in the 70V26S55J8 differ from standard memory locations?

The semaphore flags in the 70V26S55J8 reside in a separate 8-location register space, accessed only when SEM = VIL (not during normal RAM operation). Each flag is a dedicated latch controlled by A0–A2, with active-low token semantics: writing '0' requests the token, writing '1' releases it. Unlike main memory, semaphores are immune to simultaneous access conflicts and provide atomic set/test capability for inter-processor synchronization.

Can the 70V26S55J8 operate with mixed voltage interfaces (e.g., 3.3 V core, 5 V I/O)?

No, the 70V26S55J8 is strictly a 3.3 V ±0.3 V device with TTL-compatible input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) and 3.3 V output swing. It is not 5 V tolerant: applying 5 V to any input pin exceeds absolute maximum rating (VTERM ≤ +4.6 V) and risks permanent damage. Level-shifting circuitry is required for interfacing with 5 V controllers or peripherals.

What is the significance of the 'S' suffix in 70V26S55J8?

The 'S' in 70V26S55J8 denotes the standard power version of the IDT70V26 family, distinguishing it from the low-power 'L' variant (e.g., 70V26L55J8). The 'S' version has typical active power of 300 mW and standby current of 3.3 mW, optimized for performance-critical applications where power efficiency is secondary to speed and feature completeness.