Renesas 71V3557S85PFGI8

Overview

71V3557S85PFGI8 from Integrated Device Technology is a 128K × 36-bit (4.5 Mbit), 3.3V synchronous ZBT™ SRAM with flow-through outputs, 100 MHz 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 network switch fabric memory subsystems.

For engineers reviewing the 71V3557S85PFGI8 datasheet, 71V3557S85PFGI8 pinout, 71V3557S85PFGI8 application, or 71V3557S85PFGI8 equivalent, key selection criteria include ZBT™ timing compliance, TQFP-100 package compatibility, 3.3V core/I/O supply requirements, burst counter behavior under ADV/LD control, and sleep mode (ZZ) support for power-sensitive embedded systems.

Technical Context

The 71V3557S85PFGI8 implements a synchronous dual-edge-triggered interface with address/control registered on CLK rising edge and data output flow-through (no output register). Its internal burst counter advances on ADV/LD = HIGH, with sequence order selected by static LBO pin (linear or interleaved).

Three chip enables (CE1, CE2, CE2) provide flexible depth expansion; CEN suspends all synchronous operation without affecting output state; OE is asynchronous and optional (can be tied low). The device includes optional IEEE 1149.1 JTAG test logic with TMS/TDI/TCK/TDO/TRST pins and supports sleep mode via synchronous ZZ input.

Key Specifications

Pinout & Package

71V3557S85PFGI8 is packaged in a JEDEC-standard 100-pin thin quad flatpack (TQFP), 14 mm × 20 mm body, 0.5 mm pitch. Pin 1 marked with dot; top-side marking includes "71V3557S", date code, and manufacturer logo.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1355BV18-100BZXI and AS7C33128PFSIG, the 71V3557S85PFGI8 delivers unique ZBT™ timing, integrated burst control, JTAG testability, and sleep mode-making it optimal for complex, power-aware, high-throughput networking and signal processing designs where feature integration reduces system-level component count.

Availability

71V3557S85PFGI8 is available at Aetrix Electronics and suitable for network packet buffering, telecom switch fabric memory, industrial PLC data logging, and radar signal processing applications requiring stable component supply across extended product lifecycles.

Supply support for 71V3557S85PFGI8 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) is a fabless semiconductor company specializing in high-performance timing, memory interface, RF, and power management ICs for communications, computing, and industrial markets.

The 71V3557S85PFGI8 belongs to IDT's ZBT™ SRAM product line, engineered specifically for zero-latency memory subsystems in high-speed networking equipment and real-time embedded systems demanding deterministic access and low power.

FAQ

What is the memory organization and total capacity of the 71V3557S85PFGI8?

The 71V3557S85PFGI8 is organized as 128K × 36 bits, delivering 4,718,592 bits (4.5 Mbit) of synchronous SRAM. It also supports a 256K × 18-bit configuration using the same physical array-address mapping differs, but pinout and timing remain identical. This dual-configuration flexibility allows system designers to match bus width without changing layout.

How does the ZBT™ (Zero Bus Turnaround) feature work in the 71V3557S85PFGI8?

The ZBT™ feature in the 71V3557S85PFGI8 eliminates idle cycles between consecutive read and write operations. Unlike conventional SRAMs that require bus turnaround time, the 71V3557S85PFGI8 allows immediate back-to-back access-e.g., a read followed by a write on the next clock edge-without inserting wait states. This is achieved via internal pipelining and dedicated address/control registration synchronized to CLK.

Does the 71V3557S85PFGI8 support burst mode, and how is burst order controlled?

Yes, the 71V3557S85PFGI8 supports 4-word burst mode for both reads and writes. Burst sequencing is determined by the LBO (Linear/Interleaved Burst Order) pin: LBO = LOW selects linear order (A0, A1, A2, A3); LBO = HIGH selects interleaved order (A0, A1, A2, A3 mapped as 00, 01, 10, 11). The burst counter advances on ADV/LD = HIGH and wraps automatically after four words.

What is the function of the ZZ pin on the 71V3557S85PFGI8, and what power savings does it provide?

The ZZ pin on the 71V3557S85PFGI8 enables synchronous sleep mode: when asserted HIGH, it internally gates the CLK signal and powers down non-essential circuitry while guaranteeing data retention. Power consumption drops significantly-typical standby current falls to <100 µA-making the 71V3557S85PFGI8 suitable for intermittently active systems like remote telemetry nodes or battery-backed industrial loggers.

Is JTAG boundary scan supported on the 71V3557S85PFGI8, and which pins are used?

Yes, the 71V3557S85PFGI8 includes optional IEEE 1149.1-compliant JTAG boundary scan. Pins TMS, TDI, TCK, TDO, and TRST (optional reset) implement the test access port. TRST has an internal pull-up and may be left floating if unused. JTAG functionality is present in all "S" and "SA" versions, enabling board-level interconnect testing and in-system diagnostics without requiring additional test hardware.