Renesas 71V3556SA166BQ8

Overview

71V3556SA166BQ8 from IDT (now Renesas) is a 3.3V, 128K × 36-bit synchronous ZBT™ SRAM with zero bus turnaround, 166 MHz operation, 3.5 ns clock-to-data access, pipelined outputs, and JTAG boundary scan (IEEE 1149.1). It serves as high-speed cache or buffer memory in network packet processors and telecom line cards requiring deterministic burst read/write without dead cycles.

For engineers reviewing the 71V3556SA166BQ8 datasheet, 71V3556SA166BQ8 pinout, 71V3556SA166BQ8 application, or 71V3556SA166BQ8 equivalent, key selection criteria include its 100-pin TQFP package, 4-word interleaved/linear burst capability, individual byte write control (BW1–BW4), industrial temperature support (–40°C to +85°C), and optional JTAG test interface for system-level validation.

Technical Context

The 71V3556SA166BQ8 implements a fully synchronous, pipelined architecture where address/control signals are registered on the rising edge of CLK, and data transfers occur two cycles later. Its ZBT™ feature eliminates bus turnaround latency by enabling immediate read-after-write or write-after-read transitions without idle cycles.

It integrates an on-chip burst counter controlled by ADV/LD and LBO pins, supporting both linear and interleaved 4-word sequences. The device uses separate VDD (3.3V core) and VDDQ (3.3V I/O) supplies, includes three chip enables (CE1, CE2, CE2) for depth expansion, and features asynchronous OE for output tri-state control independent of clock timing.

Key Specifications

Pinout & Package

Packaged in a JEDEC-standard 100-pin plastic thin quad flatpack (TQFP), 14 mm × 20 mm body, 0.5 mm pitch. Pin 64 supports ZZ (sleep mode) on latest die revision; pins 14, 16, and 66 tolerate VIH-level input without direct VDD connection.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1356BV18-167BZI and AS7C33128PFSI-166BIN, the 71V3556SA166BQ8 uniquely delivers 128K×36-bit density with ZBT™, 4-word burst, and integrated JTAG-all in a drop-in compatible 100-pin TQFP package-making it optimal for upgrade paths in legacy telecom and networking hardware.

Availability

71V3556SA166BQ8 is available at Aetrix Electronics and suitable for high-speed network switching, telecom line card buffering, industrial PLC data logging, radar signal processing, and JTAG-enabled system validation requiring stable component supply across extended product lifecycles.

Supply support for 71V3556SA166BQ8 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 fabless semiconductor company specializing in high-performance timing, memory, and interface solutions for communications, computing, and industrial markets.

The 71V3556SA166BQ8 belongs to IDT's ZBT™ SRAM product line, designed specifically for applications demanding deterministic, low-latency memory access with zero bus turnaround-targeting network infrastructure, telecom equipment, and real-time embedded systems.

FAQ

What is the memory organization and bus width of the 71V3556SA166BQ8?

The 71V3556SA166BQ8 is configured as 128K × 36-bit, providing a total capacity of 4.5 Mbit. It supports a 36-bit data bus with four 9-bit byte lanes (I/O0–I/O31 plus I/OP1–I/OP4), enabling full-word or selective byte writes via BW1–BW4 signals. This organization matches common packet-processing and telecom payload widths.

Does the 71V3556SA166BQ8 support burst read and write operations?

Yes, the 71V3556SA166BQ8 supports 4-word burst operations in both linear and interleaved sequences, selected by the LBO pin. Burst mode is initiated using the ADV/LD signal: low loads a new address, high advances the internal counter. Burst reads/writes complete in four consecutive cycles without reissuing addresses, improving throughput in sequential access scenarios.

What is the role of the ZZ pin on the 71V3556SA166BQ8?

The ZZ pin on the 71V3556SA166BQ8 is a synchronous sleep mode input. When driven high, it internally gates the clock and places the device in its lowest power consumption state while guaranteeing data retention. This feature is especially valuable in radar or portable telecom equipment where periodic low-power operation is required without losing buffered content.

Is JTAG boundary scan available on the 71V3556SA166BQ8, and which pins implement it?

Yes, the 71V3556SA166BQ8 includes optional IEEE 1149.1-compliant JTAG boundary scan. In the 100-pin TQFP package, TMS, TDI, TCK, and TDO are assigned to pins R1, P1, R2, and P2 respectively; TRST is not implemented in TQFP but appears in BGA variants. All JTAG pins have internal pull-ups except TRST (pull-up) and ZZ (pull-down).

How does the ZBT™ feature eliminate bus turnaround latency in the 71V3556SA166BQ8?

The ZBT™ (Zero Bus Turnaround) feature in the 71V3556SA166BQ8 removes dead cycles between successive read and write operations by allowing immediate transition from one to the other on the same bus. Unlike conventional SRAMs requiring bus release/reacquisition, the 71V3556SA166BQ8 uses internal pipelining and synchronized control to maintain continuous data flow-achieving 100% bus utilization at 166 MHz.