Texas Instruments SN74V3640-6PEU

Overview

SN74V3640 from Texas Instruments is a 3.3-V CMOS, 1024 × 36-bit synchronous FIFO memory with independent read/write clocks, user-selectable bus sizing (×36/×18/×9), and first-word fall-through (FWFT) or standard timing modes. It delivers 166-MHz operation (6-ns cycle time), 5-V-tolerant inputs, and zero-latency retransmit capability for high-throughput data buffering in telecom and video interfaces.

For engineers reviewing the SN74V3640 datasheet, SN74V3640 pinout, SN74V3640 application, or SN74V3640 equivalent, key selection criteria include its 128-pin TQFP package, programmable almost-empty/almost-full flags with eight default offsets, big/little-endian byte configuration, and dual-clock domain support for asynchronous data rate matching.

Technical Context

The SN74V3640 implements a dual-clock, depth-expandable FIFO architecture with separate WCLK/RCLK domains enabling simultaneous read/write at up to 166 MHz. Its RAM array is paired with configurable flag logic supporting both FWFT (first-word appears after three RCLK edges without REN) and standard mode (REN required for all reads).

Bus-matching is controlled via BM/IW/OW pins during master reset, enabling five input/output width combinations (e.g., ×36 in → ×9 out). Flag behavior-including EF/OR, FF/IR, HF, PAE, and PAF-is determined by timing mode and programmable offset registers loaded serially (via FWFT/SI) or in parallel (via Dn), with synchronous/asynchronous timing selectable per flag via PFM.

Key Specifications

Pinout & Package

SN74V3640 is housed in a 128-pin Thin Quad Flat Pack (TQFP) with 0.4-mm lead pitch, optimized for high-density PCB layouts and thermal performance in industrial and telecom modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FIFO memory applications.

Compared with IDT72V3640 and NB3N502, SN74V3640 uniquely combines 5-V-tolerant inputs, FWFT timing, and full ×36/×18/×9 bus matching - making it the only option for high-fidelity, multi-standard interface bridging in telecom and broadcast equipment.

Availability

SN74V3640 is available at Aetrix Electronics and suitable for network packet buffering, video frame synchronization, DSP pipeline interfacing, telecom line card buffering, and high-speed data acquisition systems requiring stable component supply across extended production lifecycles.

Supply support for SN74V3640 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74V3640 belongs to TI's high-speed synchronous FIFO product line, engineered specifically for low-latency, multi-clock-domain data buffering in telecom infrastructure, broadcast video, and real-time signal processing systems.

FAQ

What is the maximum operating frequency of the SN74V3640?

The SN74V3640 supports up to 166 MHz for both read and write operations, corresponding to a 6-ns read/write cycle time. This specification is guaranteed over the commercial temperature range (0°C to 70°C) and at 3.3-V supply voltage. The device maintains full functionality with independent WCLK and RCLK frequencies, including cases where one clock is stopped while the other remains active.

Does the SN74V3640 support 5-V logic inputs?

Yes, the SN74V3640 features 5-V-tolerant inputs on all control and data pins (WEN, REN, WCLK, RCLK, D0–D35, etc.), allowing direct connection to 5-V TTL or CMOS logic without level-shifting circuitry. This capability is explicitly confirmed in the SCAS668A datasheet and applies regardless of the state of OE or bus-width configuration.

How does the first-word fall-through (FWFT) mode work in the SN74V3640?

In FWFT mode, the first word written to an empty SN74V3640 appears on Q0–Q35 after exactly three rising edges of RCLK - no REN assertion is required. Subsequent words still require REN. The mode is selected by holding FWFT/SI high during master reset (MRS), and the behavior is hardware-enforced with fixed latency, enabling deterministic startup in streaming applications.

Can the SN74V3640 be used to match a 36-bit input bus to an 18-bit output bus?

Yes, the SN74V3640 supports ×36 in → ×18 out configuration via BM, IW, and OW pin states during master reset (BM=H, IW=L, OW=L per Table 1). In this mode, D0–D17 are active inputs, Q0–Q17 are active outputs, and the remaining pins are don't-care - enabling seamless width conversion without external multiplexing.

What is the purpose of the partial reset (PRS) function in the SN74V3640?

The partial reset (PRS) input in the SN74V3640 resets the internal read and write pointers to zero and clears the output register, but preserves all programmable settings - including FWFT/standard mode, bus-width configuration, flag offsets, and timing modes. This allows safe mid-operation reinitialization without losing customized flag thresholds or endian configuration.