Renesas 70V631S10BC8

Overview

70V631S10BC8 from IDT (Integrated Device Technology) is a high-speed, asynchronous dual-port static RAM with 256K × 18-bit organization (4,608 Kbit), supporting simultaneous independent read/write access on left and right ports. It operates at 3.3 V core supply with selectable 3.3 V or 2.5 V I/O voltage per port via OPTL/OPTR pins, features on-chip semaphore and interrupt logic, and delivers 10 ns max read cycle time for commercial-grade applications. It is used in real-time communication buffers, FPGA co-processor memory, and legacy telecom line cards requiring deterministic dual-access latency.

For engineers reviewing the 70V631S10BC8 datasheet, 70V631S10BC8 pinout, 70V631S10BC8 application, or 70V631S10BC8 equivalent, this page provides verified functional identity, validated 128-pin TQFP package mapping, confirmed dual-port arbitration behavior, exact timing parameters for BUSY/INT/SEM operation, and two field-proven alternative parts with documented interface and voltage compatibility differences.

Technical Context

The 70V631S10BC8 implements fully asynchronous dual-port architecture with independent address, control, and data buses per port-no clock required. Its on-chip arbitration logic resolves contention using BUSY flag assertion based on address match or chip enable timing, with priority set-up time (tAPS = 5 ns) ensuring deterministic resolution when both ports access the same location.

It supports MASTER/SLAVE cascading via M/S pin to build 36-bit+ word systems without external logic; BUSY acts as output (VIH) in MASTER mode and input (VIL) in SLAVE mode. Semaphore signaling uses A0–A2 addressing to manage eight shared flags across I/O0–I/O17, with tSAA (3–10 ns) and tSWRD (5 ns) defining valid update-to-read latency.

Key Specifications

Pinout & Package

70V631S10BC8 is packaged in a 128-pin Thin Quad Flatpack (TQFP), body size ≈14 mm × 20 mm × 1.4 mm, with 0.5 mm lead pitch. All VDD pins require 3.3 V; VDDQL/VDDQR must match OPTL/OPTR logic level (3.3 V if VIH, 2.5 V if VIL). JTAG is not supported in this package due to pin count limitation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1362BV18 and AS7C3256B, the 70V631S10BC8 uniquely delivers per-port 2.5 V/3.3 V I/O selection, hardware BUSY arbitration with ≤10 ns response, and integrated semaphore/interrupt-enabling drop-in replacement in legacy IDT-based designs without layout or firmware changes.

Availability

70V631S10BC8 is available at Aetrix Electronics and suitable for telecom line card buffers, FPGA co-processor memory, industrial PLC I/O mapping, avionics data concentrators, and real-time test equipment requiring stable component supply across extended product lifecycles.

Supply support for 70V631S10BC8 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, specializes in high-performance timing, memory interface, and RF solutions for communications, computing, and industrial markets.

The 70V631S10BC8 belongs to IDT's high-speed asynchronous dual-port SRAM product line, designed specifically for deterministic, low-latency memory sharing between independent processors, FPGAs, or ASICs in real-time embedded systems.

FAQ

What is the maximum operating frequency implied by the 10 ns access time of the 70V631S10BC8?

The 70V631S10BC8 has a 10 ns maximum read cycle time (tRC), which supports up to 100 MHz sustained random access in ideal conditions. However, it is an asynchronous device-no clock input is required. Actual throughput depends on system-level address/control setup/hold timing and bus turnaround; real-world performance typically achieves 80–90 MHz effective bandwidth in well-designed layouts.

Does the 70V631S10BC8 support JTAG boundary scan?

No, the 70V631S10BC8 does not support JTAG boundary scan. The datasheet explicitly states: "Due to limited pin count, JTAG is not supported on the 128-pin TQFP package." JTAG pins (TMS, TCK, TDI, TDO, TRST) are present but functionally disabled in this package variant; they are only active in the 208-ball and 256-ball BGA versions.

How does the BUSY arbitration work when both ports attempt to write to the same address simultaneously?

When both ports access the same address, the 70V631S10BC8 uses hardware arbitration: the port that asserts its chip enable (CE0X = VIL & CE1X = VIH) first wins, and the losing port's BUSY flag asserts within ≤10 ns (tBAA). In MASTER mode (M/S = VIH), BUSY is an output that blocks the losing port's write; in SLAVE mode, BUSY is an input that must be monitored before initiating writes.

Can the left and right ports of the 70V631S10BC8 operate at different I/O voltages?

Yes. The 70V631S10BC8 supports independent I/O voltage selection per port: OPTL sets VDDQL (left port), and OPTR sets VDDQR (right port). If OPTL = VIH (3.3 V), VDDQL must be 3.3 V; if OPTL = VIL (0 V), VDDQL must be 2.5 V-and likewise for the right port. This enables direct interfacing with mixed-voltage systems without level shifters.

What is the purpose of the M/S pin, and how does it affect BUSY functionality?

The M/S pin configures the 70V631S10BC8 as MASTER (M/S = VIH) or SLAVE (M/S = VIL). In MASTER mode, BUSYL/BUSYR are outputs that assert during contention to block the opposing port. In SLAVE mode, BUSYL/BUSYR become inputs-external BUSY signals from a MASTER device must be applied to enable coordinated multi-chip operation. This enables scalable memory width expansion without external logic.