Renesas 71V3556SA166BGI8

Overview

71V3556SA166BGI8 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 support. It serves as a high-bandwidth, low-latency memory buffer in network packet processors and telecom line cards requiring burst reads/writes without dead cycles.

For engineers reviewing the 71V3556SA166BGI8 datasheet, 71V3556SA166BGI8 pinout, 71V3556SA166BGI8 application, or 71V3556SA166BGI8 equivalent, key selection criteria include ZBT timing compliance, 100-pin TQFP package compatibility, industrial temperature range (–40°C to +85°C), 4-word burst capability, and optional IEEE 1149.1 JTAG test interface integration.

Technical Context

The 71V3556SA166BGI8 implements a fully synchronous, positive-edge-triggered architecture with registered address, data, and control inputs. 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 4-word burst counter (linear or interleaved via LBO pin), individual byte write enables (BW1–BW4), three chip enables (CE1, CE2, CE2) for depth expansion, and a synchronous clock enable (CEN) that gates internal clocks while preserving register state. The optional JTAG interface supports boundary scan testing per IEEE 1149.1.

Key Specifications

Pinout & Package

Packaged in a JEDEC-standard 100-pin plastic thin quad flatpack (TQFP), 14 mm × 20 mm body, with 0.5 mm pitch. Pin 64 supports ZZ (sleep mode) on latest die revision; pins 14/16/66 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 71V3556SA133BGI8 and 71V3556SA166BG8, the 71V3556SA166BGI8 uniquely delivers both maximum 166 MHz performance and industrial-temperature JTAG testability - essential for carrier-class infrastructure where field-replaceable modules require post-deployment diagnostics.

Availability

71V3556SA166BGI8 is available at Aetrix Electronics and suitable for telecom switch line cards, wireless baseband units, and network packet processors requiring stable component supply, long-term lifecycle assurance, and industrial-grade thermal reliability.

Supply support for 71V3556SA166BGI8 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 and computing markets.

The 71V3556SA166BGI8 belongs to IDT's ZBT SRAM product line, engineered specifically for zero-latency, high-throughput memory subsystems in telecom infrastructure, network processors, and real-time signal processing systems.

FAQ

What is the memory organization and total capacity of the 71V3556SA166BGI8?

The 71V3556SA166BGI8 is organized as 128K × 36 bits, delivering 4,718,592 bits (4.5 Mbit) of synchronous SRAM. This configuration supports 36-bit data paths common in network processors and DSPs. All 36 bits are accessible per cycle, with I/O0–I/O31 and I/OP1–I/OP4 forming the complete 36-bit bus. The device does not support 256K × 18 mode - that applies only to the 71V3558 family variant.

Does the 71V3556SA166BGI8 support burst operations, and how is burst order controlled?

Yes, the 71V3556SA166BGI8 supports 4-word burst operations using an on-chip counter. Burst order is selected via the LBO (Linear/Interleaved Burst Order) pin: LBO = LOW enables linear addressing (A0, A0+1, A0+2, A0+3), while LBO = HIGH selects interleaved order (A0, A0+2, A0+1, A0+3). The ADV/LD pin controls counter advancement (HIGH) or new address loading (LOW), and the burst sequence wraps automatically upon completion.

What is the role of the ZZ pin on the 71V3556SA166BGI8, and how does it affect power consumption?

The ZZ pin on the 71V3556SA166BGI8 is a synchronous sleep mode input. When driven HIGH, it internally gates the clock and places the device in its lowest power state while guaranteeing data retention. This reduces dynamic power significantly during idle periods without requiring external clock stopping or complex power sequencing. ZZ has an internal pulldown resistor and must be held HIGH for sleep entry; it is not a reset or standby pin.

How many chip enable signals does the 71V3556SA166BGI8 have, and what are their polarities?

The 71V3556SA166BGI8 has three chip enable signals: CE1 and CE2 are active LOW, while CE2 is active HIGH. Chip selection requires CE1 = LOW, CE2 = LOW, and CE2 = HIGH simultaneously. Deselection occurs if any one of these conditions fails, initiating a two-cycle tri-state transition on the I/O bus. This three-signal scheme enables flexible depth expansion with minimal external logic.

Is JTAG boundary scan supported on the 71V3556SA166BGI8, and which pins are used?

Yes, the 71V3556SA166BGI8 includes optional IEEE 1149.1-compliant JTAG boundary scan. Pins TMS, TDI, TCK, TDO, and TRST (optional reset) are dedicated to this function and appear on the 100-pin TQFP package. TRST has an internal pullup and may be left floating if unused. JTAG support enables production testability and interconnect verification - a key differentiator versus non-SA variants like the 71V3556S series.