Texas Instruments SN74V245-20PAG

Overview

SN74V245-20PAG from Texas Instruments is a 4096 × 18-bit synchronous FIFO memory IC with 7.5-ns read/write cycle time, 3.3-V V_CC, and 5-V input tolerance. It supports FWFT or standard timing modes, dual-register-buffered EF/OR and FF/IR flags, and programmable almost-empty/almost-full flags for DSP-to-processor and DSP-to-AFE buffering in high-speed data acquisition systems.

For engineers reviewing the SN74V245-20PAG datasheet, SN74V245-20PAG pinout, SN74V245-20PAG application, or SN74V245-20PAG equivalent, key selection criteria include its 4096-word depth, 18-bit bus width, asynchronous/coincident clock support, half-full flag capability, and 64-pin TQFP package compatibility with TI TMS320 DSP glueless interfacing.

Technical Context

This synchronous FIFO employs independent read and write clocks (RCLK/WCLK), each gated by enable signals (REN/WEN), enabling flexible interface timing between DSPs, microprocessors, and buses. Its internal RAM array is paired with dedicated read/write pointers, offset registers, and flag logic supporting both FWFT and standard modes.

Flag behavior is mode-dependent: EF/OR and FF/IR are dual-function (empty/output-ready, full/input-ready); PAE/PAF are programmable with default offsets of 127 from empty/full; HF is available in single-device configuration. All flags update synchronously on RCLK or WCLK rising edges per mode configuration.

Key Specifications

Pinout & Package

Packaged in a 64-pin thin quad flat package (TQFP), SN74V245-20PAG features 18-bit bidirectional data paths (D0–D17 inputs, Q0–Q17 outputs), dual-clock domain controls (RCLK/WCLK), and mode-selectable expansion pins (WXI/RXI/FL).

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72V2105L15PF and NB3N502MNG, SN74V245-20PAG uniquely delivers 4096-word depth, FWFT timing, 5-V input tolerance, and three independent programmable flags - making it irreplaceable for high-throughput, mixed-voltage DSP glue logic where latency, expandability, and precise buffer management are critical.

Availability

SN74V245-20PAG is available at Aetrix Electronics and suitable for DSP interface design, high-speed data acquisition, and real-time signal processing applications requiring stable component supply across extended production lifecycles.

Supply support for SN74V245-20PAG 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 digital signal processing technologies, with decades of expertise in high-performance timing and interface solutions.

SN74V245-20PAG belongs to the DSP-SYNC™ family of synchronous FIFOs engineered specifically for glueless interfacing between TI TMS320 DSPs and peripheral subsystems, emphasizing low-latency, expandable buffering, and robust flag control.

FAQ

What is the memory organization and maximum operating frequency of SN74V245-20PAG?

SN74V245-20PAG features a 4096 × 18-bit memory array, providing 73,728 bits of synchronous FIFO storage. It supports read/write cycle times of 7.5 ns, enabling reliable operation at up to 133 MHz clock frequency. This performance is validated across the full 0°C to 70°C commercial temperature range and is integral to its use in high-speed DSP interfacing applications.

Does SN74V245-20PAG support both FWFT and standard timing modes, and how is the mode selected?

Yes, SN74V245-20PAG supports both first-word fall-through (FWFT) and standard timing modes. Mode selection is determined during reset (RS) by the logic states of FL, RXI, and WXI pins as defined in the truth table of the datasheet. In FWFT mode, the first written word appears on Q outputs after three RCLK transitions without asserting REN; in standard mode, REN must be asserted for every read, including the first word.

What are the default offset values for the programmable almost-empty and almost-full flags in SN74V245-20PAG?

For SN74V245-20PAG, the default empty offset is 127 words from empty, and the default full offset is 127 words from full - consistent across SN74V225, SN74V235, and SN74V245 variants. These values are loaded into internal offset registers at power-up or reset and can be reprogrammed via D0–D11 and the LD/WEN control sequence.

Can SN74V245-20PAG be used in systems with mixed 3.3-V and 5-V logic levels?

Yes, SN74V245-20PAG operates from a 3.3-V V_CC supply but features 5-V tolerant inputs on all control and data pins (D0–D17, REN, WEN, etc.). This eliminates the need for external level shifters when interfacing with legacy 5-V peripherals or mixed-signal subsystems, simplifying board design and improving signal integrity in DSP glue logic applications.

How does the half-full (HF) flag function in SN74V245-20PAG, and when is it available?

The half-full (HF) flag in SN74V245-20PAG is active-low and available only in single-device or width-expansion configurations (not in daisy-chain depth expansion). It asserts low when more than half the FIFO memory is filled - i.e., after 2049th word write for SN74V245-20PAG - and resets high on the next RCLK edge once the fill level drops to ≤2048 words. HF provides hardware-triggered flow control without CPU polling.