Renesas 70T631S15BF

Overview

70T631S15BF from Integrated Device Technology is a high-speed 256K × 18-bit asynchronous dual-port static RAM with true simultaneous access, 15 ns max access time, single 2.5 V core supply, and selectable 2.5 V/3.3 V I/O interface per port. It supports RapidWrite Mode for back-to-back writes and on-chip semaphore arbitration, enabling real-time inter-processor communication in telecom line cards.

For engineers reviewing the 70T631S15BF datasheet, 70T631S15BF pinout, 70T631S15BF application, or 70T631S15BF equivalent, key selection criteria include dual-port timing independence, BUSY/INT flag behavior in MASTER/SLAVE configurations, sleep mode current (≤10 mA), JTAG IEEE 1149.1 compliance in BGA-208, and voltage-flexible I/O control via OPTL/OPTR pins.

Technical Context

This device implements fully asynchronous dual-port architecture with independent address, control, and data buses per port-no shared clock required. Each port features separate CE0/CE1 enables, R/W, OE, UB/LB byte controls, and dedicated BUSY/INT flags tied to on-chip arbitration logic.

RapidWrite Mode eliminates need to toggle R/W between consecutive writes; address transition defines write end, reducing system timing overhead. Semaphore registers (A0–A2) are accessed via CE=VIH/SEM=VIL, supporting eight hardware flags for inter-processor synchronization without external logic.

Key Specifications

Pinout & Package

70T631S15BF 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 validated per IDT DSC-5670/11 Rev. AUGUST 2019.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1362BV25 and 72T36115L15BFI, the 70T631S15BF uniquely delivers per-port I/O voltage flexibility, RapidWrite Mode for burst writes, and integrated sleep mode - critical for power-constrained, mixed-voltage, high-throughput dual-processor systems.

Availability

70T631S15BF is available at Aetrix Electronics and suitable for telecom infrastructure, industrial automation, and test equipment requiring stable component supply, long-lifecycle support, and guaranteed commercial-grade temperature performance.

Supply support for 70T631S15BF 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, designs high-performance timing, memory, and interface solutions for communications, computing, and industrial markets.

The 70T63x family was engineered specifically for deterministic, low-latency inter-processor communication in real-time embedded systems - emphasizing hardware arbitration, voltage flexibility, and rapid sequential access.

FAQ

What is the maximum operating temperature range for the 70T631S15BF?

The 70T631S15BF is rated for commercial temperature operation only: 0°C to +70°C. It does not support the industrial –40°C to +85°C range. This is explicitly stated in the Recommended Operating Conditions table (DSC-5670/11, Table 4), where only Commercial grade is listed for the 70T631S15 speed bin.

Does the 70T631S15BF support JTAG boundary scan?

Yes, the 70T631S15BF supports IEEE 1149.1 JTAG boundary scan, but only in the 208-ball BGA (BF208/BFG208) package. The feature is not available in the 256-ball variant. Pins TDO, TDI, TCK, TMS, and TRST are present and functional per the pin configuration diagram (DSC-5670/11, Page 4).

How does the RapidWrite Mode function in the 70T631S15BF?

In RapidWrite Mode, the 70T631S15BF allows consecutive write operations without toggling R/W, CE, or byte enables between addresses. The write cycle ends on the address transition, not the R/W deassertion. This requires meeting tAAS (≤1 ns skew) and tARF (≥1.5 V/ns) to prevent spurious writes - detailed in DSC-5670/11, Table 14 and Figure 8.

What is the role of the OPTL and OPTR pins on the 70T631S15BF?

OPTL and OPTR configure the I/O voltage level per port: VSS selects 2.5 V operation (VDDQL/VDDQR = 2.5 V), VDD selects 3.3 V operation (VDDQL/VDDQR = 3.3 V). This allows independent 2.5 V and 3.3 V interfacing on left and right ports - confirmed in DSC-5670/11, Note 3 on Page 5 and Table 5/6.

Can the 70T631S15BF be used in MASTER/SLAVE configurations for wider data buses?

No - the 70T631S15BF is limited to 256K × 18 and has A18 marked NC, so it cannot be cascaded as MASTER/SLAVE for 36-bit expansion. That capability applies only to the 70T633/1 (512K × 18) variant, as explicitly noted in the datasheet: "IDT70T633/1 easily expands data bus width… M/S = VIH for BUSY output flag on Master" - a feature absent in 70T631.