Renesas 71V3556S166PFG8

Overview

71V3556S166PFG8 from IDT (now Renesas) is a 128K × 36-bit, 4.5-Mbit, 3.3V synchronous ZBT™ SRAM with zero bus turnaround, pipelined outputs, and 166 MHz operation (3.5 ns clock-to-data access). It features 4-word burst capability (linear/interleaved), individual byte write control (BW1–BW4), and three chip enables for depth expansion - deployed in high-speed networking buffers, packet switching ASIC interfaces, and real-time DSP memory subsystems.

For engineers reviewing the 71V3556S166PFG8 datasheet, 71V3556S166PFG8 pinout, 71V3556S166PFG8 application, or 71V3556S166PFG8 equivalent, key selection criteria include ZBT™ bus turnaround elimination, 166 MHz synchronous timing compliance, TQFP-100 packaging with verified 100-pin JEDEC footprint, industrial temperature support (–40°C to +85°C), and JTAG boundary-scan readiness (IEEE 1149.1).

Technical Context

The 71V3556S166PFG8 implements a fully pipelined architecture with positive-edge-triggered address, data, and control registers synchronized to CLK. Its internal burst counter advances on ADV/LD = HIGH, while external address loading occurs on ADV/LD = LOW - enabling seamless interleaving between load and burst cycles without dead cycles.

ZBT™ operation eliminates bus turnaround latency by allowing immediate read-after-write or write-after-read transitions via dedicated R/W control and synchronized OE-independent output buffering. The device supports both linear and interleaved burst sequences selected by static LBO input, with all I/O paths registered for deterministic 3.5 ns t_CD timing at 166 MHz.

Key Specifications

Pinout & Package

71V3556S166PFG8 is packaged in a JEDEC-standard 100-pin plastic thin quad flatpack (TQFP), 14 mm × 20 mm body size, with 0.5 mm pitch leads. Pin 1 is located at top-left corner (notch-mark side), and pin numbering proceeds counterclockwise.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1362BV33-166AXC and AS7C33128PFS-166BIN, the 71V3556S166PFG8 uniquely delivers 36-bit width with per-byte write enables, true ZBT™ bus turnaround elimination, and industrial-grade reliability in TQFP - making it optimal for telecom and industrial control where deterministic timing and protocol alignment are non-negotiable.

Availability

71V3556S166PFG8 is available at Aetrix Electronics and suitable for high-speed packet switching, real-time DSP memory subsystems, and industrial PLC data logging requiring stable component supply across extended product lifecycles.

Supply support for 71V3556S166PFG8 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, specializes in high-performance timing, memory interface, and RF solutions for communications and computing infrastructure.

The 71V3556S166PFG8 belongs to IDT's ZBT™ SRAM family, engineered specifically for zero-latency memory subsystems in network processors, switch fabrics, and real-time signal processing platforms demanding deterministic 166 MHz throughput.

FAQ

What is the memory organization and total capacity of the 71V3556S166PFG8?

The 71V3556S166PFG8 is configured as 128K × 36-bit, delivering a total capacity of 4,718,592 bits (4.5 Mbit). This organization supports full 36-bit word access or granular 9-bit byte writes using BW1–BW4 signals - essential for protocol-aware memory systems where field-level updates are required without full-word overwrites.

Does the 71V3556S166PFG8 support burst mode, and how is burst order controlled?

Yes, the 71V3556S166PFG8 supports 4-word burst mode with selectable linear or interleaved sequencing. Burst order is determined by the static LBO pin: LOW selects linear (0,1,2,3), HIGH selects interleaved (0,2,1,3). The ADV/LD pin controls whether the internal burst counter advances (HIGH) or loads a new external address (LOW), enabling seamless burst chaining.

What is the function of the ZZ pin on the 71V3556S166PFG8, and how does it affect power consumption?

The ZZ pin on the 71V3556S166PFG8 is a synchronous sleep mode input. When driven HIGH, it gates the internal clock and reduces dynamic power consumption to its lowest level while maintaining full data retention. This feature is critical for energy-sensitive applications such as battery-backed industrial controllers or fanless telecom modules where thermal headroom is constrained.

Is JTAG boundary scan supported on the 71V3556S166PFG8 in its TQFP-100 package?

No, JTAG boundary scan (IEEE 1149.1) is not supported on the 71V3556S166PFG8 in the PFG8 (TQFP-100) package. JTAG signals (TMS, TDI, TCK, TDO, TRST) are only available in BGA variants (e.g., BG119, BQ165) and marked as NC (no connect) in TQFP pinouts. The 71V3556S166PFG8 datasheet explicitly confirms JTAG is optional and package-dependent.

How does the 71V3556S166PFG8 achieve zero bus turnaround, and what design benefit does this provide?

The 71V3556S166PFG8 achieves zero bus turnaround (ZBTTM) through dedicated R/W control and internally synchronized output buffering that eliminates the need for external OE timing coordination. This allows immediate read-after-write or write-after-read transitions without dead cycles - sustaining >95% bus utilization in high-throughput applications like packet switching and real-time DSP, where traditional SRAMs incur 1–2 cycle penalties per direction change.