Renesas 70T631S12BCI8

Overview

70T631S12BCI8 from IDT (now Renesas) is a high-speed 256K × 18-bit asynchronous dual-port static RAM with independent left/right ports, 12 ns max access time, 2.5 V core supply, and selectable 2.5 V/3.3 V I/O interface per port - used in real-time inter-processor communication, FPGA co-processor buffering, and legacy bus arbitration systems.

For engineers reviewing the 70T631S12BCI8 datasheet, 70T631S12BCI8 pinout, 70T631S12BCI8 application, or 70T631S12BCI8 equivalent, key selection criteria include simultaneous dual-port read/write capability, RapidWrite Mode timing compliance, BUSY flag arbitration logic, and BGA-208 package compatibility with industrial temperature support (–40°C to +85°C).

Technical Context

This device implements true dual-port SRAM architecture with on-chip port arbitration, semaphore signaling, and JTAG IEEE 1149.1 test support. It operates fully asynchronously - no clock required - with separate CE0/CE1 enables, R/W controls, and byte-select (UB/LB) per port.

Each port supports independent power domains: fixed 2.5 V core (VDD) and configurable I/O voltage (VDDQ) via OPTL/OPTR pins, enabling mixed-voltage system interfacing. Sleep mode (ZZL/ZZR) reduces current to ≤10 mA while preserving JTAG accessibility.

Key Specifications

Pinout & Package

70T631S12BCI8 is packaged in a 208-ball fine-pitch BGA (BF208/BFG208), 15 mm × 15 mm × 1.4 mm body, 0.8 mm ball pitch. Pin functions are strictly defined per port (Left/Right), with dedicated arbitration (BUSY/INT/SEM), byte enable (UBL/LBL, UBR/LBR), and sleep (ZZL/ZZR) signals.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1362BV18-12BGXI and AS7C3256B-12JIN, the 70T631S12BCI8 uniquely delivers per-port voltage configurability, integrated BUSY arbitration, and RapidWrite Mode - making it the sole option among these three that eliminates external logic for real-time dual-processor memory sharing.

Availability

70T631S12BCI8 is available at Aetrix Electronics and suitable for real-time inter-processor communication, FPGA co-processor buffering, and legacy bus arbitration systems requiring stable component supply, long-term lifecycle assurance, and industrial-grade reliability.

Supply support for 70T631S12BCI8 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

Renesas Electronics (formerly Integrated Device Technology) designs high-performance memory and timing solutions for mission-critical embedded systems, with leadership in dual-port SRAM, clock generation, and interface ICs.

The 70T631S12BCI8 belongs to IDT's 70T63x family of asynchronous dual-port SRAMs, engineered specifically for deterministic, low-latency inter-processor communication in industrial automation, aerospace avionics, and telecom infrastructure.

FAQ

What is the memory organization and maximum access time of the 70T631S12BCI8?

The 70T631S12BCI8 is a 256K × 18-bit asynchronous dual-port SRAM with a maximum access time (tAA) of 12 ns across the full industrial temperature range (–40°C to +85°C). Address pin A18 is No Connect, confirming the 256K depth. This specification is guaranteed under VDD = 2.5 V ±100 mV and appropriate VDDQ supply conditions.

Does the 70T631S12BCI8 support mixed-voltage I/O operation between its two ports?

Yes, the 70T631S12BCI8 supports independent I/O voltage selection per port via OPTL and OPTR pins. Setting OPTL to VSS configures the left port for 2.5 V I/O operation (requiring VDDQL = 2.5 V), while setting OPTR to VDD configures the right port for 3.3 V I/O (requiring VDDQR = 3.3 V). This enables direct interfacing with heterogeneous system components.

How does the RapidWrite Mode function in the 70T631S12BCI8, and what timing constraints apply?

RapidWrite Mode in the 70T631S12BCI8 allows consecutive write cycles without toggling R/W, CE, or byte enables - address transition defines cycle end. It requires meeting tAAS (≤1 ns address skew) and tARF (≥1.5 V/ns rise/fall) on address lines. All standard write specs (tWC, tDW, tDH) still apply, but tAS and tWR are only relevant when switching between read and write operations.

What is the role of the BUSY flag and how is it configured for master/slave operation in the 70T631S12BCI8?

In the 70T631S12BCI8, BUSYL and BUSYR serve as contention resolution flags: when M/S = VIH, the port acts as Master and asserts BUSY as an output; when M/S = VIL, it acts as Slave and accepts BUSY as an input. This hardware arbitration prevents data corruption during simultaneous access to the same memory location by two processors or controllers.

Is JTAG boundary scan supported on the 70T631S12BCI8, and which package variants include it?

Yes, the 70T631S12BCI8 supports IEEE 1149.1 JTAG boundary scan (TCK, TMS, TDI, TDO, TRST) - but only in BGA-208 (BF208/BFG208) and BGA-256 packages. JTAG remains functional during sleep mode (ZZ asserted), though operation is not recommended in that state. Pins are dedicated and electrically isolated from memory I/O functions.