Renesas 71V2556S166PFG8

Overview

71V2556S166PFG8 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), pipelined outputs, and zero bus turnaround architecture. It supports 4-word linear/interleaved burst reads/writes, individual byte write control (BW1–BW4), and operates across industrial temperature range (–40°C to +85°C) in a 100-pin TQFP package - deployed in high-speed network packet buffers and telecom line-card memory subsystems.

For engineers reviewing the 71V2556S166PFG8 datasheet, 71V2556S166PFG8 pinout, 71V2556S166PFG8 application, or 71V2556S166PFG8 equivalent, key selection considerations include its ZBT™ timing behavior, 2.5V I/O supply compatibility, JTAG boundary-scan support (optional), and dual-burst-mode flexibility via LBO pin - critical for deterministic latency in switch fabric and cache-coherent interconnect designs.

Technical Context

The 71V2556S166PFG8 implements a fully synchronous, clock-edge-triggered architecture with address/data/control registers aligned to the rising CLK edge. Its internal burst counter and ADV/LD-controlled address loading enable deterministic 4-cycle burst sequences without external sequencing logic.

ZBT™ operation eliminates dead cycles between read/write transitions by overlapping bus turnaround with next-cycle setup; OE is internally synchronized, removing timing-critical external gating. The device supports three chip enables (CE1, CE2, CE2) for depth expansion and CEN for full clock suspension - preserving register state during idle periods.

Key Specifications

Pinout & Package

Packaged in a JEDEC-standard 100-pin plastic thin quad flatpack (TQFP), 14 mm × 20 mm body, 0.5 mm pitch. Pin 1 marked by dot; top view orientation per datasheet drawing 4875 drw 02.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1362BV18-167BZC and AS7C33128P-166JCIN, the 71V2556S166PFG8 uniquely combines 2.5V I/O support, integrated burst counter, ZBT™ timing, and TQFP packaging - making it the only option for retrofitting legacy 2.5V I/O systems with deterministic high-speed buffering without board redesign.

Availability

71V2556S166PFG8 is available at Aetrix Electronics and suitable for network packet buffering, telecom line-card memory, baseband processor caching, and radar signal processing applications requiring stable component supply and long-term industrial-grade availability.

Supply support for 71V2556S166PFG8 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 fabless semiconductor company specializing in high-performance timing, memory interface, and RF solutions for communications and computing markets.

The 71V2556S166PFG8 belongs to IDT's ZBT™ SRAM product line, designed specifically for low-latency, high-throughput buffering in packet-switched networks, telecom infrastructure, and real-time signal processing systems where deterministic timing and bus efficiency are critical.

FAQ

What is the maximum operating frequency of the 71V2556S166PFG8?

The 71V2556S166PFG8 is rated for a maximum clock frequency of 166 MHz, corresponding to a 6.0 ns clock period and guaranteed 3.5 ns clock-to-data access time (tCD). This specification is validated over the full industrial temperature range (–40°C to +85°C) and 3.3 V ±5% VDD supply, ensuring reliable operation in thermally demanding environments like telecom chassis.

Does the 71V2556S166PFG8 support JTAG boundary scan?

Yes, the 71V2556S166PFG8 supports IEEE 1149.1-compliant JTAG boundary scan as an optional feature. Pins TMS, TDI, TCK, TDO, and TRST are assigned in the 100-pin TQFP package (see Pin Configuration drawing 4875 drw 13a), though JTAG functionality is only implemented in the "SA" variant - the "S" version (including 71V2556S166PFG8) has these pins designated NC. Confirm variant suffix before relying on JTAG.

How does the ZBT™ architecture improve performance in the 71V2556S166PFG8?

The ZBT™ (Zero Bus Turnaround) architecture in the 71V2556S166PFG8 eliminates dead cycles between consecutive read and write operations by overlapping bus direction control with address setup. This enables back-to-back bursts without idle cycles, increasing effective bandwidth by up to 33% compared to standard synchronous SRAMs - a critical advantage in packet buffering and cache-coherent interconnects.

What is the function of the LBO pin on the 71V2556S166PFG8?

The LBO (Linear/Interleaved Burst Order) pin on the 71V2556S166PFG8 selects the burst addressing sequence: pulled to VSS for linear order (A0, A1, A2, A3) or to VDD for interleaved order (A0, A2, A1, A3). This allows runtime adaptation to system requirements - linear mode suits cache-line-aligned accesses, while interleaved mode optimizes for DMA engines expecting strided addressing patterns.

Can the 71V2556S166PFG8 operate with mixed voltage supplies?

Yes, the 71V2556S166PFG8 uses separate power domains: VDD = 3.3 V ±5% for core logic and VDDQ = 2.5 V for I/O circuitry. This dual-supply design isolates noise-sensitive I/O from the core, enables interoperability with 2.5V ASICs/FPGAs, and complies with JEDEC SSTL_2 standards - verified across all recommended operating conditions in the datasheet DC characteristics table.