Renesas 71V3557S85PFGI

Overview

IDT71V3557S85PFGI from Integrated Device Technology is a 128K × 36-bit, 4.5 Mbit synchronous ZBT™ SRAM with 3.3V core/I/O supply, 100 MHz operation (7.5 ns clock-to-data access), flow-through outputs, and 4-word burst capability. It implements zero bus turnaround for seamless read/write transitions in high-speed memory subsystems of network switches and telecom line cards.

For engineers reviewing the IDT71V3557S85PFGI datasheet, IDT71V3557S85PFGI pinout, IDT71V3557S85PFGI application, or IDT71V3557S85PFGI equivalent, key selection criteria include ZBT™ timing compliance, TQFP-100 package compatibility, 3.3V I/O voltage tolerance, linear/interleaved burst mode support via LBO, and JTAG boundary-scan testability per IEEE 1149.1.

Technical Context

The IDT71V3557S85PFGI uses a synchronous dual-register architecture: address/control signals are latched on the rising CLK edge when ADV/LD is low and chip enables are asserted, while data output follows one cycle later without an output register (flow-through). Burst sequencing is controlled by ADV/LD high (increment internal counter) and LBO (linear vs. interleaved order).

It integrates three chip enables (CE1, CE2 active-low; CE2 active-high) for depth expansion, individual byte write enables (BW1–BW4) for partial writes, and optional IEEE 1149.1 JTAG with TMS/TDI/TCK/TDO/TRST pins. Sleep mode (ZZ high) gates CLK internally to minimize power while retaining data.

Key Specifications

Pinout & Package

Package: 100-pin thin quad flatpack (TQFP), 14 mm × 20 mm, JEDEC standard, lead-free and RoHS compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT71V3557S85PFGI, CY7C1355KV18 offers identical speed but reduced configurability and testability, while IS61WV102436B trades ZBT™ simplicity for higher density and speed-requiring careful bus protocol design to avoid turnaround penalties.

Availability

IDT71V3557S85PFGI is available at Aetrix Electronics and suitable for network packet buffering, telecom line card memory, and industrial PLC data logging requiring stable component supply, long-term lifecycle support, and industrial temperature qualification.

Supply support for IDT71V3557S85PFGI 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, RF, and power management solutions for communications and computing infrastructure.

IDT71V3557S85PFGI belongs to IDT's ZBT™ SRAM product line, engineered specifically for zero-latency, high-throughput memory subsystems in networking, telecom, and real-time embedded systems where deterministic timing is critical.

FAQ

What is the memory organization and density of the IDT71V3557S85PFGI?

The IDT71V3557S85PFGI is organized as 128K × 36 bits, delivering a total capacity of 4,718,592 bits (4.5 Mbit). It supports both 128K × 36 and 256K × 18 configurations via pin-compatible variants, with the IDT71V3557S85PFGI specifically configured for the 128K × 36 mode. This structure provides 36-bit wide data paths ideal for high-bandwidth packet buffering and descriptor storage in telecom and networking applications.

Does the IDT71V3557S85PFGI support burst mode, and how is it controlled?

Yes, the IDT71V3557S85PFGI supports a 4-word synchronous burst mode controlled by the ADV/LD and LBO pins. When ADV/LD is sampled high on the rising clock edge, the internal burst counter increments, generating sequential addresses. The LBO pin selects between linear (LBO = low) and interleaved (LBO = high) burst sequences. This eliminates external address generation logic and reduces bus overhead during consecutive memory accesses.

What is the role of the ZZ pin on the IDT71V3557S85PFGI, and how does it affect power consumption?

The ZZ pin on the IDT71V3557S85PFGI is a synchronous sleep mode input. When driven high, it gates the internal clock distribution network, reducing dynamic power consumption to its lowest level while guaranteeing data retention. This feature is especially valuable in industrial and telecom applications where intermittent operation or thermal management requires power gating without losing buffered state-critical for IDT71V3557S85PFGI deployments in energy-sensitive line cards and remote base stations.

Is JTAG boundary scan supported on the IDT71V3557S85PFGI, and which pins are involved?

Yes, the IDT71V3557S85PFGI includes optional IEEE 1149.1-compliant JTAG boundary scan functionality. The dedicated pins are TMS (Test Mode Select), TDI (Test Data Input), TCK (Test Clock), TDO (Test Data Output), and TRST (optional JTAG reset). These signals are routed to pins 89–93 on the 100-pin TQFP package and enable structural interconnect testing, in-system verification, and debug visibility without requiring physical probe access-enhancing test coverage for IDT71V3557S85PFGI in high-density PCB assemblies.

How does the ZBT™ (Zero Bus Turnaround) feature improve system performance in the IDT71V3557S85PFGI?

The ZBT™ feature in the IDT71V3557S85PFGI eliminates dead cycles between alternating read and write operations by allowing immediate bus direction reversal without wait states. Unlike conventional SRAMs that require explicit turnaround cycles, IDT71V3557S85PFGI transitions seamlessly between reads and writes on consecutive clocks-enabling sustained 100 MHz throughput in packet-forwarding engines, cache controllers, and real-time DSP buffers where deterministic latency is non-negotiable.