Renesas 71V2556S166PFGI8

Overview

71V2556S166PFGI8 from IDT (now Renesas) is a 3.3V synchronous ZBT™ SRAM with 128K × 36-bit organization (4.5 Mbit), 166 MHz operation (3.5 ns clock-to-data access), and pipelined burst outputs. It features Zero Bus Turnaround for dead-cycle-free read/write transitions, individual byte write control (BW1–BW4), and supports linear/interleaved 4-word bursts in high-speed networking and packet buffering applications.

For engineers reviewing the 71V2556S166PFGI8 datasheet, 71V2556S166PFGI8 pinout, 71V2556S166PFGI8 application, or 71V2556S166PFGI8 equivalent, key selection considerations include its 100-pin TQFP package, 2.5V I/O supply (VDDQ), industrial temperature range (–40°C to +85°C), JTAG support (optional), and compatibility with high-throughput memory interfaces requiring deterministic latency and burst efficiency.

Technical Context

The 71V2556S166PFGI8 implements a fully synchronous, clock-edge-triggered architecture with address/data/control registers aligned to the rising edge of CLK. Its internal burst counter and LBO-controlled linear/interleaved addressing enable predictable 4-word data delivery without external sequencing logic.

ZBT™ operation eliminates bus turnaround delay by overlapping write completion and read initiation within the same clock domain. The device uses separate 3.3V core (VDD) and 2.5V I/O (VDDQ) supplies, with OE internally synchronized to eliminate asynchronous timing constraints, and CEN enabling full clock gating for power management.

Key Specifications

Pinout & Package

Packaged in a JEDEC-standard 100-pin plastic thin quad flatpack (TQFP), 14 mm × 20 mm body size, with exposed thermal pad (PFGI8 suffix denotes industrial-grade TQFP with lead-free finish).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1355BV18-167BZI and AS7C3256A-15TIN, the 71V2556S166PFGI8 uniquely delivers ZBT™ zero-turnaround, 100-pin TQFP packaging, and 2.5V I/O compatibility - making it optimal for upgrade paths from older IDT ZBT SRAMs and mixed-voltage high-speed interface designs.

Availability

71V2556S166PFGI8 is available at Aetrix Electronics and suitable for network packet buffering, telecom switch fabric memory, and industrial real-time control applications requiring stable component supply, long-term lifecycle support, and industrial temperature qualification.

Supply support for 71V2556S166PFGI8 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, is a semiconductor company specializing in high-performance timing, memory interface, and RF solutions for communications and computing infrastructure.

The 71V2556S166PFGI8 belongs to IDT's ZBT™ SRAM product line, engineered specifically for high-throughput, low-latency memory subsystems in networking, telecom, and test equipment where deterministic burst access and bus efficiency are critical.

FAQ

What is the operating temperature range for the 71V2556S166PFGI8?

The 71V2556S166PFGI8 is rated for industrial temperature operation from –40°C to +85°C. This specification is validated across all electrical parameters in the datasheet and applies to the PFGI8 package variant. It ensures reliable functionality in base station equipment, industrial PLCs, and outdoor networking hardware where ambient conditions exceed commercial-grade limits.

Does the 71V2556S166PFGI8 support JTAG boundary scan?

Yes, the 71V2556S166PFGI8 supports IEEE 1149.1-compliant JTAG boundary scan as an optional feature. Pins TMS, TDI, TCK, TDO, and TRST are assigned to dedicated balls/pins in the 100-pin TQFP package (U1–U5). JTAG functionality is enabled only when the SA version is used; the 'S' version (like 71V2556S166PFGI8) has these pins marked NC but may retain internal TAP logic depending on die revision.

What is the purpose of the LBO pin on the 71V2556S166PFGI8?

The LBO (Linear/Interleaved Burst Order) pin on the 71V2556S166PFGI8 selects the burst address sequence: tied to VSS for linear order (0,1,2,3) or to VDD for interleaved order (0,2,1,3). This configuration determines how the internal burst counter increments during multi-word read/write cycles and must be set statically at power-up to match the host ASIC's expected burst pattern.

How does the ZBTTM feature improve system performance in the 71V2556S166PFGI8?

ZBTTM (Zero Bus Turnaround) in the 71V2556S166PFGI8 eliminates idle cycles between consecutive read and write operations. Unlike conventional SRAMs that require turnaround time to change bus direction, the 71V2556S166PFGI8 allows immediate transition - e.g., a write cycle can be followed directly by a read cycle on the next clock edge - sustaining peak bandwidth and reducing average memory access latency in burst-heavy workloads.

Can the 71V2556S166PFGI8 operate with only a 3.3V supply, or is the 2.5V VDDQ rail mandatory?

The 2.5V VDDQ supply is mandatory for the 71V2556S166PFGI8. While VDD (core) operates at 3.3V ±5%, the I/O buffers are designed exclusively for 2.5V signaling. Applying 3.3V to VDDQ violates absolute maximum ratings and risks permanent damage. The dual-supply architecture isolates core logic noise from sensitive I/O drivers, ensuring signal integrity at 166 MHz.