Renesas 71V3557S85PFG

Overview

71V3557S85PFG 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 cache coherency logic in telecom switching fabric.

For engineers reviewing the 71V3557S85PFG datasheet, 71V3557S85PFG pinout, 71V3557S85PFG application, or 71V3557S85PFG 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-gated systems.

Technical Context

The 71V3557S85PFG implements a synchronous dual-edge-triggered address/control register pipeline with flow-through output path - no output data register - enabling deterministic 1-cycle read latency after address load. Its burst counter advances on ADV/LD = HIGH and loads new external addresses on ADV/LD = LOW, with LBO selecting linear or interleaved sequence.

ZBT™ operation eliminates dead cycles between read/write transitions via synchronized chip enable (CE1/CE2/CE2) and R/W-controlled bus direction management. Clock Enable (CEN) gates internal clock propagation without affecting output state, while ZZ input enables low-power sleep mode with guaranteed data retention.

Key Specifications

Pinout & Package

71V3557S85PFG is packaged in a JEDEC-standard 100-pin thin quad flatpack (TQFP), 14 mm × 20 mm body, 0.5 mm pitch. Pin 1 is located at top-left corner (marking dot adjacent), with pins numbered counter-clockwise. Thermal pad is not present; thermal dissipation relies on PCB copper area under exposed center pad (non-electrical).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1355BV33-100BGXI and AS7C33128PFSIG, the 71V3557S85PFG uniquely delivers ZBT™ timing, integrated burst counter, and sleep mode in a single TQFP-100 package - making it irreplaceable in telecom buffer and real-time control applications demanding deterministic latency and power-aware operation.

Availability

71V3557S85PFG is available at Aetrix Electronics and suitable for telecom infrastructure, industrial automation, and radar signal processing applications requiring stable component supply, long-term lifecycle support, and industrial-temperature-grade reliability.

Supply support for 71V3557S85PFG 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 high-performance data conversion solutions.

The 71V3557S85PFG belongs to IDT's ZBT™ SRAM product line, designed specifically for high-speed networking, telecommunications, and real-time embedded systems where deterministic latency and bus efficiency are critical.

FAQ

What is the maximum operating frequency and corresponding access time for the 71V3557S85PFG?

The 71V3557S85PFG operates at up to 100 MHz with a guaranteed clock-to-data access time (tCD) of 7.5 ns. This specification is validated across the full industrial temperature range (–40°C to +85°C) and 3.3 V ±5% supply conditions. The 71V3557S85PFG achieves this performance using IDT's high-speed CMOS process and flow-through output architecture, eliminating output register delay.

Does the 71V3557S85PFG support both linear and interleaved burst modes, and how is the selection controlled?

Yes, the 71V3557S85PFG supports both linear and interleaved 4-word burst sequences. Selection is controlled by the static LBO (Linear/Interleaved Burst Order) input: LBO = LOW selects linear order (0,1,2,3), and LBO = HIGH selects interleaved order (0,2,1,3). The 71V3557S85PFG requires LBO to remain stable during burst execution to prevent undefined address sequencing.

How does the ZBT™ (Zero Bus Turnaround) feature function in the 71V3557S85PFG, and what design benefit does it provide?

The ZBT™ feature in the 71V3557S85PFG eliminates dead cycles between successive read and write operations by synchronizing bus direction control with chip enable and R/W signals. This allows immediate transition from write to read (or vice versa) without bus idle time. In the 71V3557S85PFG, this is implemented via synchronous CE1/CE2/CE2 logic and flow-through outputs, enabling >95% bus utilization in high-throughput packet buffering applications.

What is the role of the ADV/LD pin in the 71V3557S85PFG, and how does it affect burst versus single-cycle operation?

The ADV/LD pin in the 71V3557S85PFG determines whether the device loads a new external address (ADV/LD = LOW) or advances the internal burst counter (ADV/LD = HIGH). When ADV/LD is LOW with chip enables asserted, the current address is latched for a single access or burst initiation. When ADV/LD is HIGH, the counter increments and next burst word is output - enabling efficient sequential access without re-driving the address bus. This dual-mode control is fundamental to the 71V3557S85PFG's burst efficiency.

Is JTAG boundary scan supported on the 71V3557S85PFG, and which pins are dedicated to this function?

Yes, the 71V3557S85PFG includes optional IEEE 1149.1 JTAG boundary scan support. 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 mapped to pins in the TQFP-100 package (e.g., TMS = pin U16, TDI = pin U15, TCK = pin U14, TDO = pin U13, TRST = pin U12), and all have internal pull-ups except TRST (internal pull-up) and ZZ (internal pulldown).