Renesas 71V2556S166PFGI

Overview

71V2556S166PFGI from IDT (now Renesas) is a 128K × 36-bit (4.5 Mbit), 3.3V synchronous ZBT™ SRAM with 2.5V I/O, pipelined outputs, and zero-bus-turnaround architecture. It operates at 166 MHz (3.5 ns clock-to-data access), supports 4-word linear/interleaved burst, individual byte write control (BW1–BW4), and features internal burst counter, clock enable (CEN), and three chip enables (CE1/CE2/CE2) for depth expansion. It is used in high-speed packet buffering and network switch fabric memory subsystems.

For engineers reviewing the 71V2556S166PFGI datasheet, 71V2556S166PFGI pinout, 71V2556S166PFGI application, or 71V2556S166PFGI equivalent, key selection considerations include its ZBT™ timing behavior, 100-pin TQFP package with VDDQ/VSS decoupling requirements, industrial temperature range (–40°C to +85°C), JTAG optional support (IEEE 1149.1), and compatibility with 3.3V core / 2.5V I/O system interfaces.

Technical Context

The 71V2556S166PFGI implements a fully synchronous, clock-edge-triggered architecture with address, data, and control registers aligned to the rising edge of CLK. Its ZBT™ operation eliminates dead cycles between read/write transitions via internally synchronized output buffer enable and pipelined output register staging.

It integrates a 4-word burst counter controlled by ADV/LD and LBO pins, supporting both linear and interleaved addressing sequences. The device uses separate 3.3V (VDD) and 2.5V (VDDQ) supplies, with dedicated VSS planes and on-die termination support for signal integrity in high-speed bus environments.

Key Specifications

Pinout & Package

71V2556S166PFGI is packaged in a JEDEC-standard 100-pin plastic thin quad flatpack (TQFP), 14 mm × 20 mm body, 0.5 mm pitch, with exposed thermal pad (PFGI suffix denotes industrial temp, lead-free, RoHS-compliant).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1355BV166BZC and AS7C3256B-166JCIN, the 71V2556S166PFGI uniquely delivers true ZBT™ zero-turnaround performance, 2.5V I/O isolation, and TQFP packaging-making it optimal for new industrial networking designs demanding deterministic latency and signal integrity.

Availability

71V2556S166PFGI is available at Aetrix Electronics and suitable for network packet buffering, telecom line card memory, enterprise switch fabric, and radar signal processing applications requiring stable component supply, long-term lifecycle assurance, and industrial temperature compliance.

Supply support for 71V2556S166PFGI 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 infrastructure.

The 71V2556S166PFGI belongs to IDT's ZBT™ SRAM product line, engineered specifically for high-speed networking equipment where deterministic latency, bus efficiency, and industrial reliability are mandatory.

FAQ

What is the maximum operating frequency of the 71V2556S166PFGI?

The 71V2556S166PFGI is rated for a maximum clock frequency of 166 MHz, delivering a guaranteed 3.5 ns clock-to-data access time under industrial temperature and voltage conditions. This specification is validated across the full –40°C to +85°C range with VDD = 3.3 V ±5% and VDDQ = 2.5 V ±5%.

Does the 71V2556S166PFGI support JTAG boundary scan?

The 71V2556S166PFGI includes optional IEEE 1149.1 JTAG boundary scan functionality, implemented via dedicated TMS, TDI, TCK, TDO, and TRST pins. These pins are NC on the base "S" version but active on the "SA" variant; the PFGI package supports the SA configuration when ordered accordingly.

How does the ZBTTM feature improve system performance in the 71V2556S166PFGI?

The ZBTTM (Zero Bus Turnaround) feature in the 71V2556S166PFGI eliminates idle bus cycles between consecutive read and write operations. By internally synchronizing output enable and using pipelined registers, it enables immediate back-to-back transfers-increasing effective bus utilization by up to 30% compared to conventional synchronous SRAMs in burst-intensive applications.

What is the function of the ADV/LD and LBO pins on the 71V2556S166PFGI?

On the 71V2556S166PFGI, ADV/LD controls burst initiation: LOW loads an external address into the internal counter; HIGH increments the counter for subsequent burst words. LBO selects burst order-tied to VSS for linear (0,1,2,3), VDD for interleaved (0,2,1,3)-enabling compatibility with industry-standard memory controller addressing schemes.

Can the 71V2556S166PFGI operate with only 3.3V supply, or is 2.5V I/O mandatory?

The 71V2556S166PFGI requires two distinct supplies: 3.3V ±5% on VDD for core logic and 2.5V ±5% on VDDQ for I/O drivers. Operating with only 3.3V on VDDQ violates absolute maximum ratings and risks damage or undefined behavior-the 2.5V I/O rail is mandatory for correct signal levels, timing, and drive strength compliance.