Renesas 71V3557S85BGI8

Overview

71V3557S85BGI8 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 71V3557S85BGI8 datasheet, 71V3557S85BGI8 pinout, 71V3557S85BGI8 application, or 71V3557S85BGI8 equivalent, key selection criteria include ZBT™ timing compliance, TQFP-100 package compatibility, 3.3V core/I/O supply tolerance, burst counter synchronization with ADV/LD, and sleep mode (ZZ) support for power-sensitive telecom line cards.

Technical Context

The 71V3557S85BGI8 implements a synchronous dual-edge-triggered address/control register interface with flow-through output path-no output register-enabling deterministic 1-cycle read latency after address load. Its internal burst counter advances on ADV/LD = HIGH and loads new addresses on ADV/LD = LOW, with LBO pin selecting linear or interleaved sequence order.

Three chip enables (CE1, CE2 active-low; CE2 active-high) enable depth expansion without external logic; CEN suspends all synchronous operation while preserving register state; OE remains asynchronous for fast output disable. The device integrates IEEE 1149.1 JTAG test circuitry with optional TRST and supports guaranteed data retention in ZZ sleep mode.

Key Specifications

Pinout & Package

71V3557S85BGI8 is housed in a JEDEC-standard 100-pin thin quad flatpack (TQFP), 14 mm × 20 mm body, 0.5 mm pitch. Pin 1 marked by dot; pins 14, 64, and 66 require VSS connection per latest die revision (pin 64 supports ZZ sleep mode).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1355KV18-100BZI and AS7C3256P-10JIN, the 71V3557S85BGI8 uniquely delivers ZBT™-optimized timing, integrated JTAG, and industrial-grade sleep mode in a manufacturable TQFP package-critical for next-gen telecom infrastructure where latency, test coverage, and thermal resilience are co-constrained.

Availability

71V3557S85BGI8 is available at Aetrix Electronics and suitable for network switch buffering, telecom line card memory, and baseband processing cache applications requiring stable component supply across extended product lifecycles.

Supply support for 71V3557S85BGI8 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 sensor solutions for communications and computing markets.

The 71V3557S85BGI8 belongs to IDT's ZBT™ SRAM product line, engineered specifically for high-speed networking equipment requiring deterministic latency, zero bus turnaround, and robust industrial temperature operation.

FAQ

What is the maximum operating frequency and corresponding access time for the 71V3557S85BGI8?

The 71V3557S85BGI8 operates up to 100 MHz with a guaranteed clock-to-data access time (tCD) of 7.5 ns. This specification ensures deterministic read latency from CLK rising edge to valid data on I/O pins under industrial temperature conditions (–40°C to +85°C) and 3.3 V ±5% supply.

Does the 71V3557S85BGI8 support burst read and write operations, and how is burst order controlled?

Yes, the 71V3557S85BGI8 supports 4-word synchronous burst operations for both reads and writes. Burst order is selected via the LBO pin: LBO = LOW enables linear sequence (0,1,2,3), while LBO = HIGH selects interleaved (0,2,1,3). LBO is static and must remain stable during burst execution.

How does the ZBT™ (Zero Bus Turnaround) feature function in the 71V3557S85BGI8?

ZBT™ in the 71V3557S85BGI8 eliminates dead cycles between consecutive read and write operations by allowing immediate bus direction reversal. Unlike conventional SRAMs requiring turnaround cycles, the 71V3557S85BGI8 permits back-to-back reads and writes with no inserted wait states-critical for high-throughput packet buffering.

What is the role of the ZZ pin on the 71V3557S85BGI8, and what power savings does it provide?

The ZZ pin on the 71V3557S85BGI8 enables synchronous sleep mode: when asserted HIGH, it gates the internal clock and reduces dynamic power consumption to minimum while guaranteeing full data retention. Power savings exceed 60% during idle periods, validated across the –40°C to +85°C industrial range.

Is JTAG boundary scan supported on the 71V3557S85BGI8, and which pins implement the interface?

Yes, the 71V3557S85BGI8 includes IEEE 1149.1-compliant JTAG boundary scan. Pins TMS, TDI, TCK, TDO, and optional TRST implement the interface. TRST is pull-up internally and may be left floating if unused; all JTAG signals are synchronous and referenced to CLK.