Renesas 71V2556SA166BG8

Overview

71V2556SA166BG8 from IDT (now Renesas) is a 3.3V synchronous ZBT™ SRAM with 128K × 36-bit organization (4.5 Mbit), 166 MHz clock frequency (3.5 ns clock-to-data access), and pipelined outputs. It supports zero-bus-turnaround (ZBT) operation, individual byte write control (BW1–BW4), and burst read/write modes (linear or interleaved) - deployed in high-speed networking packet buffers and cache subsystems.

For engineers reviewing the 71V2556SA166BG8 datasheet, 71V2556SA166BG8 pinout, 71V2556SA166BG8 application, or 71V2556SA166BG8 equivalent, key selection criteria include ZBT timing compliance, 2.5V I/O voltage compatibility, 119-ball BGA (BG119) package footprint, industrial temperature range (–40°C to +85°C), and JTAG boundary-scan support for testability.

Technical Context

This SRAM implements a fully synchronous, positive-edge-triggered architecture with address/data/control registers, an on-chip 4-word burst counter, and internally synchronized output enable (OE). The ADV/LD pin controls burst counter increment (HIGH) or external address load (LOW), while LBO selects linear vs. interleaved burst order.

It features three chip enables (CE1, CE2, CE2) for depth expansion, clock enable (CEN) for cycle suspension, and optional IEEE 1149.1 JTAG interface (TMS/TDI/TCK/TDO/TRST) on dedicated pins. All I/Os operate at 2.5V (VDDQ), while core logic runs at 3.3V (VDD), with separate VSS planes for analog and digital domains.

Key Specifications

Pinout & Package

71V2556SA166BG8 is packaged in a JEDEC-standard 119-ball grid array (BG119) with 1.0 mm ball pitch and exposed thermal pad. Pinout conforms to IDT's BG119 mechanical drawing (document 4875 drw 13a), supporting industrial temperature operation and optional JTAG test access.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous SRAM applications.

Compared with CY7C1355BV18-167BZXI and AS7C3256B-167BIN, the 71V2556SA166BG8 uniquely delivers industrial-grade reliability, ZBT timing, 2.5V I/O compatibility, and JTAG testability in a space-efficient BGA - making it the only option for ruggedized, high-throughput embedded memory subsystems.

Availability

71V2556SA166BG8 is available at Aetrix Electronics and suitable for network packet buffering, telecom baseband processing, industrial motion control, and high-speed cache subsystems requiring stable component supply across extended lifecycle windows.

Supply support for 71V2556SA166BG8 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), now part of Renesas Electronics, specializes in high-performance timing, memory interface, and RF solutions for communications and computing infrastructure.

The 71V2556SA166BG8 belongs to IDT's ZBT™ SRAM product line, engineered specifically for zero-latency bus turnaround in high-speed packet-processing and cache-coherent subsystems demanding deterministic timing and industrial reliability.

FAQ

What is the maximum operating frequency and corresponding access time for the 71V2556SA166BG8?

The 71V2556SA166BG8 is rated for a maximum clock frequency of 166 MHz, with a guaranteed clock-to-data access time of 3.5 ns. This specification applies under industrial temperature conditions (–40°C to +85°C) and nominal supply voltages (VDD = 3.3 V ±5%, VDDQ = 2.5 V). The 71V2556SA166BG8 achieves this performance using fully pipelined synchronous architecture and ZBTTM bus protocol.

Does the 71V2556SA166BG8 support JTAG boundary scan, and which pins are used?

Yes, the 71V2556SA166BG8 supports optional IEEE 1149.1 JTAG boundary scan. Pins TMS, TDI, TCK, TDO, and TRST (ball positions U5, U4, U3, U2, and U1 respectively in BG119 layout) implement the JTAG interface. TRST is optional and internally pulled to VDD if left floating; all JTAG pins are NC on non-SA variants but functional on the 71V2556SA166BG8.

How does the ZBTTM feature eliminate dead cycles in the 71V2556SA166BG8?

The ZBTTM (Zero Bus Turnaround) feature in the 71V2556SA166BG8 allows immediate transition from a write cycle to a read cycle (or vice versa) without inserting idle bus cycles. This is achieved through internal pipelining and burst counter synchronization, ensuring that the bus remains active and productive - a critical advantage in high-throughput packet buffering where 71V2556SA166BG8 sustains 166 MHz back-to-back operations.

What is the function of the LBO pin on the 71V2556SA166BG8, and how does it affect burst behavior?

The LBO (Linear/Interleaved Burst Order) pin on the 71V2556SA166BG8 selects burst sequence mode: pulled to VSS for linear order (0,1,2,3) or to VDD for interleaved order (0,2,1,3). This directly determines how the internal burst counter increments addresses during 4-word bursts, enabling optimal alignment with cache line structures or memory controller expectations - a configurable feature unique to the 71V2556SA166BG8 among its speed grade.

Is the 71V2556SA166BG8 compatible with industrial temperature requirements, and what is its qualification scope?

Yes, the 71V2556SA166BG8 is fully qualified for industrial temperature operation from –40°C to +85°C, with all AC and DC electrical specifications guaranteed across this range. It is manufactured in a JEDEC-standard 119-ball BGA package with thermal pad, and includes ZZ (deep sleep) mode support on pin T7 - making the 71V2556SA166BG8 suitable for deployment in base stations, motor drives, and other harsh-environment embedded systems.