Renesas 71V2556S150PFGI

Overview

71V2556S150PFGI from IDT (now Renesas) is a 128K × 36-bit (4.5 Mbit), 3.3V synchronous ZBT™ SRAM with pipelined outputs, 2.5V I/O supply, and zero bus turnaround architecture. It delivers 166 MHz operation (3.5 ns clock-to-data access), supports 4-word linear/interleaved burst modes, and features individual byte write control (BW1–BW4) for high-bandwidth memory subsystems in network packet buffers and telecom switching fabrics.

For engineers reviewing the 71V2556S150PFGI datasheet, 71V2556S150PFGI pinout, 71V2556S150PFGI application, or 71V2556S150PFGI equivalent, key selection criteria include its ZBT™ timing behavior, TQFP-100 package compatibility, industrial temperature range (–40°C to +85°C), and support for burst counter-controlled address sequencing without external OE management.

Technical Context

The 71V2556S150PFGI implements a fully synchronous, clock-edge-triggered architecture with input/output registers aligned to the rising edge of CLK. Its internal burst counter eliminates dead cycles between read/write transitions via ZBT™ logic, and ADV/LD controls either external address load (LOW) or internal counter increment (HIGH).

It integrates three chip enables (CE1, CE2, CE2) for depth expansion, a dedicated LBO pin selecting linear vs. interleaved burst order, and optional IEEE 1149.1 JTAG boundary scan (not enabled on "S" version). The device uses separate VDD (3.3V ±5%) and VDDQ (2.5V) supplies, with output drivers referenced to VDDQ.

Key Specifications

Pinout & Package

Packaged in a JEDEC-standard 100-pin thin quad flatpack (TQFP), 14 mm × 20 mm body, lead-free (Pb-free) and RoHS-compliant (PFGI suffix). Pin 64 supports ZZ (sleep mode) on latest die revision; pins 14, 16, and 66 require ≥VIH but need not be tied directly to VDD.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1356BV18-167BZI and AS7C3256B-15JIN, the 71V2556S150PFGI uniquely delivers ZBT™-enabled zero-cycle turnaround and integrated burst sequencing - reducing controller complexity and improving sustained bandwidth in telecom and networking memory subsystems.

Availability

71V2556S150PFGI is available at Aetrix Electronics and suitable for network packet buffering, telecom switch fabric memory, baseband processing cache, and industrial PLC data logging requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 71V2556S150PFGI 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, and interface solutions for communications and computing infrastructure.

The 71V2556S150PFGI belongs to IDT's ZBT™ SRAM product line, engineered specifically for zero-latency, high-throughput memory subsystems in carrier-class networking and telecom equipment where deterministic timing and bus efficiency are critical.

FAQ

What does the 'S' in 71V2556S150PFGI signify?

The 'S' denotes the standard version of the IDT71V2556 family, which excludes the optional JTAG boundary scan interface (IEEE 1149.1). Unlike the 'SA' variant, the 71V2556S150PFGI has TMS/TDI/TCK/TDO/TRST pins configured as No Connect (NC), simplifying layout and test for applications not requiring JTAG debug or production testing. This version retains full ZBT™ functionality, burst counter, and industrial temperature rating.

Does 71V2556S150PFGI support both linear and interleaved burst modes?

Yes, the 71V2556S150PFGI supports both linear and interleaved 4-word burst sequences, selected by the LBO (Linear/Interleaved Burst Order) pin. When LBO is tied to VSS, the burst order is linear (A, A+1, A+2, A+3); when tied to VDD, it is interleaved (A, A+2, A+1, A+3). This flexibility allows optimization for cache line alignment or specific DMA engine requirements without firmware changes.

What is the role of the ADV/LD pin in 71V2556S150PFGI operation?

The ADV/LD pin serves a dual function: when LOW, it loads a new external address into the internal address register; when HIGH, it advances the internal burst counter to generate the next sequential address. This eliminates the need for the controller to update the address bus every cycle during burst transfers, reducing bus contention and simplifying timing-critical control logic in high-speed switch fabric implementations.

How does the ZBT™ architecture in 71V2556S150PFGI improve system performance?

The ZBT™ (Zero Bus Turnaround) architecture in the 71V2556S150PFGI eliminates dead cycles between read and write operations by overlapping bus direction control with data transfer. Unlike conventional SRAMs requiring explicit OE deassertion and bus turnaround time, the 71V2556S150PFGI transitions seamlessly - enabling 100% bus utilization and up to 30% higher effective throughput in mixed-access memory subsystems such as packet buffer managers.

Is 71V2556S150PFGI compatible with 2.5V-only I/O interfaces?

Yes, the 71V2556S150PFGI uses a dedicated 2.5V I/O supply (VDDQ) and is fully compatible with 2.5V logic families. Its I/O pins are designed for VDDQ-referenced signaling, with VIH(min) = 2.0V and VIL(max) = 0.7V under recommended operating conditions. This ensures robust interoperability with FPGAs, ASICs, and processors using 2.5V I/O standards without level-shifting circuitry.