Renesas 71V2546S100BG

Overview

71V2546S100BG 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 delivers 150 MHz operation (3.8 ns clock-to-data access), supports 4-word linear/interleaved burst modes via internal counter, and features individual byte write control (BW1–BW4), three chip enables, and industrial temperature range (–40°C to +85°C). It is used in high-speed packet buffering and network switching ASIC/FPGA interfaces.

For engineers reviewing the 71V2546S100BG datasheet, 71V2546S100BG pinout, 71V2546S100BG application, or 71V2546S100BG equivalent, key selection considerations include ZBT timing compliance, 100-pin TQFP package compatibility, 2.5V I/O voltage domain separation, burst mode configuration (LBO), and industrial-grade thermal performance for telecom infrastructure designs.

Technical Context

This device implements a fully synchronous, pipelined SRAM architecture where address, control, and data are registered on the positive clock edge. The internal burst counter advances on ADV/LD = HIGH, enabling four-cycle burst reads/writes from a single address load - with sequence order (linear or interleaved) selected by LBO pin level.

ZBT functionality eliminates dead cycles between read/write transitions by overlapping bus turnaround with valid data transfer. Output enable (OE) is internally synchronized, removing external timing constraints; CEN suspends all clocked operations while preserving register state, and CE1/CE2/CE2 provide hierarchical chip select for depth expansion.

Key Specifications

Pinout & Package

71V2546S100BG is packaged in a JEDEC-standard 100-pin plastic thin quad flatpack (TQFP), 14 mm × 20 mm body size, with 0.5 mm lead pitch. Pin 1 is located at top-left corner (notch-mark side).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1354BV18-167BZI and AS7C33128PFSIG, the 71V2546S100BG uniquely delivers ZBT timing, 2.5V I/O isolation, and integrated burst control in a drop-in 100-pin TQFP footprint - making it the only option that preserves both timing determinism and layout compatibility in legacy telecom designs.

Availability

71V2546S100BG is available at Aetrix Electronics and suitable for network packet buffering, FPGA-based protocol acceleration, and telecom line card memory requiring stable component supply, long-term lifecycle support, and industrial-temperature qualification.

Supply support for 71V2546S100BG 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 markets.

The 71V2546S100BG belongs to IDT's ZBT SRAM product line, engineered specifically for zero-latency, high-throughput buffering in networking ASICs, routers, and switching fabric subsystems where deterministic burst access and bus efficiency are critical.

FAQ

What is the ZBTTM feature of the 71V2546S100BG and how does it improve system performance?

The ZBTTM (Zero Bus Turnaround) feature of the 71V2546S100BG eliminates idle cycles between consecutive read and write operations by overlapping bus direction changes with valid data transfers. This allows back-to-back memory accesses without waiting for bus stabilization, increasing effective bandwidth by up to 33% in burst-intensive applications like packet switching. Unlike conventional SRAMs, the 71V2546S100BG sustains full 150 MHz throughput even during mixed read/write sequences - a key advantage in telecom and networking hardware where latency and jitter must be minimized.

Does the 71V2546S100BG support both linear and interleaved burst modes, and how is the mode selected?

Yes, the 71V2546S100BG supports both linear and interleaved 4-word burst modes. The mode is selected via the LBO (Linear/Interleaved Burst Order) pin: tying LBO to VSS selects linear burst (A0, A1, A2, A3), while tying it to VDD selects interleaved burst (A0, A2, A1, A3). This configuration is sampled at power-up or reset and remains fixed for the duration of operation. The burst counter advances automatically on ADV/LD = HIGH, enabling fully autonomous burst addressing without external sequencing logic - a critical feature for simplifying FPGA-based memory controllers.

What are the voltage requirements for VDD and VDDQ on the 71V2546S100BG, and why are they separated?

The 71V2546S100BG requires VDD = 3.3 V ±5% for core logic and VDDQ = 2.5 V ±5% for the 36-bit I/O bus (I/O[0:31] and I/OP[1:4]). This dual-supply architecture isolates noise-sensitive I/O signaling from the higher-noise core logic domain, improving signal integrity and timing margins in high-speed systems. The separation also enables interoperability with 2.5V FPGAs and ASICs while maintaining 3.3V-compatible internal timing - a design choice optimized for mixed-voltage telecom and networking platforms where clean I/O transitions are essential for error-free data capture.

How does the 71V2546S100BG handle partial writes, and what is the role of BW1–BW4 pins?

The 71V2546S100BG supports partial writes via four active-low byte write enable pins (BW1–BW4), each controlling a 9-bit segment of the 36-bit data bus: BW1 → I/O[0:8], BW2 → I/O[9:17], BW3 → I/O[18:26], BW4 → I/O[27:31]+I/OP[1:4]. When a BWx pin is held HIGH, the corresponding byte group is masked during write cycles - allowing targeted updates to specific fields (e.g., packet headers or status flags) without performing destructive read-modify-write operations. This capability reduces bus traffic and processing overhead in protocol-aware applications, and is especially valuable in real-time systems where memory bandwidth is constrained.

Is the 71V2546S100BG available in both commercial and industrial temperature grades, and what is the significance of the 'BG' suffix?

Yes, the 71V2546S100BG is rated for the industrial temperature range of –40°C to +85°C, with full AC and DC electrical specifications guaranteed across this range. The 'BG' suffix denotes the 100-pin TQFP package variant (PKG100), distinguishing it from the BGA version (e.g., 71V2546S100BGI). This packaging choice supports standard surface-mount assembly, thermal management via exposed pad (if applicable), and mechanical robustness in vibration-prone environments such as base stations and industrial control cabinets - making the 71V2546S100BG suitable for mission-critical infrastructure where reliability under thermal stress is non-negotiable.