Renesas 71V3557S85PFG8

Overview

IDT71V3557S85PFG8 from Integrated Device Technology is a 128K × 36-bit, 4.5 Mbit synchronous ZBT™ SRAM with 3.3V core/I/O supply, 100 MHz operation (7.5 ns clock-to-data access), flow-through outputs, and burst counter for linear/interleaved 4-word sequences - used in high-speed packet buffering and cache coherency logic in telecom switching fabric.

For engineers reviewing the IDT71V3557S85PFG8 datasheet, IDT71V3557S85PFG8 pinout, IDT71V3557S85PFG8 application, or IDT71V3557S85PFG8 equivalent, key selection criteria include ZBT™ zero bus turnaround timing, synchronous byte write enables (BW1–BW4), JTAG boundary scan support, and TQFP-100 packaging with VDDQ/VDD separation for noise isolation.

Technical Context

The IDT71V3557S85PFG8 implements a synchronous dual-edge-triggered address/control register architecture with ADV/LD-driven burst counter and LBO-selectable linear or interleaved addressing. All inputs except OE and TRST are sampled on the rising edge of CLK, with CEN gating internal clock propagation when asserted high.

It features flow-through output path (no output register), asynchronous OE for tri-state control, and integrated JTAG IEEE 1149.1 test interface with TMS/TDI/TCK/TDO/TRST pins. Sleep mode (ZZ) reduces power while retaining data, and individual byte write enables allow granular 9-bit writes within the 36-bit word.

Key Specifications

Pinout & Package

Package: 100-pin thin quad flatpack (TQFP), JEDEC standard, 14 mm × 20 mm body, 0.5 mm pitch. Pin 1 marked by corner notch; pins 14, 64, 66 internally pulled to VSS or VDDQ depending on function (ZZ sleep mode supported on pin 64).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY7C1355KV18 and IS61WV102432BLL, the IDT71V3557S85PFG8 uniquely combines ZBT™ timing, JTAG testability, and 128K×36 organization - making it optimal for telecom and network processor designs demanding deterministic latency and production test coverage.

Availability

IDT71V3557S85PFG8 is available at Aetrix Electronics and suitable for telecom infrastructure, network processor design, and industrial real-time control applications requiring stable component supply across extended product lifecycles.

Supply support for IDT71V3557S85PFG8 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) was a fabless semiconductor company specializing in timing, memory interface, RF, and sensor signal conditioning ICs before its acquisition by Renesas in 2019.

The IDT71V3557S85PFG8 belongs to IDT's ZBT™ SRAM product line, engineered specifically for zero-turnaround memory subsystems in high-speed networking and communications equipment.

FAQ

What is the memory organization and total capacity of the IDT71V3557S85PFG8?

The IDT71V3557S85PFG8 is organized as 128K × 36 bits, delivering a total capacity of 4,718,592 bits (4.5 Mbit). It supports both 128K × 36 and 256K × 18 configurations via pin-compatible variants, with address pins A0–A16 used for the 128K × 36 mode. This organization enables efficient 36-bit wide data transfers common in network processor and DSP interfaces.

Does the IDT71V3557S85PFG8 support JTAG boundary scan, and which pins implement it?

Yes, the IDT71V3557S85PFG8 supports IEEE 1149.1-compliant JTAG boundary scan. The dedicated pins are TMS (Test Mode Select), TDI (Test Data Input), TCK (Test Clock), TDO (Test Data Output), and optional TRST (JTAG Reset). These are assigned to pins U16, U15, U14, U13, and U12 respectively on the 100-pin TQFP package, enabling structural test and debug in production and field environments.

How does the ZBT™ (Zero Bus Turnaround) feature work in the IDT71V3557S85PFG8?

The ZBT™ feature in the IDT71V3557S85PFG8 eliminates idle bus cycles between consecutive read and write operations. By using synchronous control signals (R/W, ADV/LD) and internal pipelining, the device allows immediate transition from a read burst to a write burst - or vice versa - without inserting wait states. This enables sustained 100 MHz throughput in applications like packet buffering where bus efficiency is critical.

What is the role of the ADV/LD and LBO pins in burst operation of the IDT71V3557S85PFG8?

ADV/LD controls burst sequencing: when low, it loads a new external address; when high, it advances the internal burst counter. LBO selects burst order - low for linear (0,1,2,3), high for interleaved (0,2,1,3) - matching memory access patterns of CPUs or DSPs. Both signals are synchronous and must be stable before the rising CLK edge to ensure deterministic burst behavior in the IDT71V3557S85PFG8.

Can the IDT71V3557S85PFG8 operate in low-power mode, and how is it enabled?

Yes, the IDT71V3557S85PFG8 supports synchronous sleep mode via the ZZ pin. When ZZ is driven high, the internal clock is gated and the device enters its lowest power state while retaining memory contents. Data retention is guaranteed across the full industrial temperature range (–40°C to +85°C). Pin 64 on the TQFP package implements ZZ, and it features an internal pulldown resistor for safe default behavior.