Renesas 71V3557S85BGI

Overview

71V3557S85BGI from Integrated Device Technology is a 128K × 36-bit (4.5 Mbit), 3.3V synchronous ZBT™ SRAM with flow-through outputs, 100 MHz clock operation (7.5 ns clock-to-data access), and zero bus turnaround architecture. It supports interleaved/linear 4-word burst reads/writes, individual byte write control (BW1–BW4), and JTAG boundary scan (IEEE 1149.1). Used in high-speed packet buffering and cache coherency logic in telecom switching fabric.

For engineers reviewing the 71V3557S85BGI datasheet, 71V3557S85BGI pinout, 71V3557S85BGI application, or 71V3557S85BGI equivalent, key selection criteria include ZBT™ timing compliance, TQFP-100 package compatibility, 3.3V I/O/core supply tolerance, burst counter behavior under ADV/LD control, and sleep mode (ZZ) power-down support for thermal management in dense memory subsystems.

Technical Context

The 71V3557S85BGI implements a synchronous dual-edge-triggered interface with address/control latching on CLK rising edge, flow-through output path (no output register), and asynchronous OE for tri-state control. Its burst counter advances on ADV/LD = HIGH and loads new addresses on ADV/LD = LOW - enabling deterministic linear or interleaved sequences selected by static LBO pin.

Three chip enables (CE1, CE2 active-low; CE2 active-high) allow depth expansion without external logic; CEN suspends all synchronous inputs while preserving internal state; ZZ enables low-power sleep mode with guaranteed data retention. JTAG test interface includes TMS, TDI, TCK, TDO, and optional TRST.

Key Specifications

Pinout & Package

71V3557S85BGI is packaged in a JEDEC-standard 100-pin thin quad flatpack (TQFP), 14 mm × 20 mm body, 0.5 mm pitch. Pin 1 marked by corner notch; top-side marking includes "71V3557S85BGI" and date code.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1355BV18-100BZI and AS7C33128PFSIG-100, the 71V3557S85BGI uniquely delivers 128K × 36-bit density with ZBT™ timing, integrated sleep mode, and TQFP-100 packaging - making it irreplaceable for legacy-compatible, thermally constrained, burst-intensive designs.

Availability

71V3557S85BGI is available at Aetrix Electronics and suitable for telecom infrastructure, industrial motion control, and radar signal processing requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 71V3557S85BGI 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

Integrated Device Technology (IDT), now part of Renesas Electronics, is a fabless semiconductor company specializing in timing, memory interface, and RF power solutions for communications and computing markets.

The 71V3557S85BGI belongs to IDT's ZBT™ SRAM product line, engineered specifically for high-bandwidth, low-latency memory subsystems in networking, storage, and real-time control applications where bus turnaround overhead must be eliminated.

FAQ

What is the maximum clock frequency supported by the 71V3557S85BGI?

The 71V3557S85BGI supports a maximum clock frequency of 100 MHz, corresponding to a 7.5 ns clock-to-data access time. This specification is guaranteed over the full industrial temperature range (–40°C to +85°C) and 3.3 V ±5% supply conditions. The 71V3557S85BGI achieves this performance using IDT's high-speed CMOS process and flow-through output architecture, eliminating output register delay.

Does the 71V3557S85BGI support both linear and interleaved burst modes?

Yes, the 71V3557S85BGI supports both linear and interleaved burst sequences via the LBO (Linear/Interleaved Burst Order) pin. When LBO is driven LOW, the device executes linear bursts (A0, A1, A2, A3); when HIGH, it uses interleaved order (A0, A2, A1, A3). The 71V3557S85BGI requires LBO to remain static during burst operation, and the sequence wraps after four words.

How does the ZBT™ feature eliminate bus turnaround cycles in the 71V3557S85BGI?

The 71V3557S85BGI implements ZBT™ (Zero Bus Turnaround) by allowing immediate transition between read and write operations without inserting idle cycles. Its internal control logic manages direction switching autonomously based on R/W and ADV/LD states, ensuring the data bus remains active. This eliminates the 1–2 cycle penalty typical of standard synchronous SRAMs, directly increasing effective bandwidth in burst-heavy workloads.

Can the 71V3557S85BGI operate with only two chip enables asserted?

Yes - the 71V3557S85BGI requires CE1 = LOW, CE2 = LOW, and CE2 = HIGH for selection. If any one of these three chip enables is invalid (e.g., CE1 = HIGH or CE2 = HIGH or CE2 = LOW), the device enters deselect mode, and the data bus tri-states one clock cycle later. This three-enable scheme enables flexible depth expansion without external logic, and the 71V3557S85BGI maintains full functionality with all three signals properly driven.

Is JTAG boundary scan mandatory or optional on the 71V3557S85BGI?

JTAG boundary scan is optional on the 71V3557S85BGI and implemented per IEEE 1149.1. Pins TMS, TDI, TCK, TDO, and optional TRST are dedicated for test; TRST may be left floating (internally pulled up) if not used. The 71V3557S85BGI supports full scan chain operation but does not require JTAG for functional operation - all memory and control features operate independently of test mode activation.