Texas Instruments SN74ACT3622-20PCB

Overview

SN74ACT3622-20PCB from Texas Instruments is a clocked bidirectional FIFO memory IC with dual 256 × 36 SRAM buffers, supporting asynchronous or coincident 67 MHz clocks (CLKA/CLKB), 11 ns access time, and programmable almost-full/almost-empty flags synchronized per port. It enables high-speed data bridging between mismatched microprocessor buses in telecom backplanes and real-time DSP interconnects.

For engineers reviewing the SN74ACT3622-20PCB datasheet, SN74ACT3622-20PCB pinout, SN74ACT3622-20PCB application, or SN74ACT3622-20PCB equivalent, key selection criteria include dual-port flag synchronization timing, mailbox-bypass register behavior, FIFO reset sequencing, and PCB-package pin compatibility with SN74ACT3632/SN74ACT3642.

Technical Context

This device integrates two independent clocked FIFOs-FIFO1 (A→B) and FIFO2 (B→A)-each backed by 256 × 36-bit SRAM and controlled by separate synchronous interfaces. CLKA governs A-port writes/reads and synchronizes IRA, ORA, AFA, AEA; CLKB governs B-port operations and synchronizes IRB, ORB, AFB, AEB.

Flag offset registers (X1/Y1 for FIFO1; X2/Y2 for FIFO2) are programmable via port-A writes or preset during reset using FS0/FS1 latching. Mailbox registers (Mail1/Mail2) provide 36-bit bypass paths with MBF1/MBF2 handshaking, decoupling control messaging from FIFO queuing latency.

Key Specifications

Pinout & Package

SN74ACT3622-20PCB uses a 120-pin Thin Quad Flat Package (TQFP), designated "PCB" in TI documentation, with 0.4 mm lead pitch and exposed thermal pad. Pin numbering follows standard TQFP top-view layout with corner pin #1 marked.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT3632-20PCB and SN74ACT3642-20PCB, SN74ACT3622-20PCB uniquely delivers mailbox-bypass capability with fully programmable flag offsets and consistent dual-stage synchronization-making it the only option among the three that supports concurrent data streaming and out-of-band control without external logic.

Availability

SN74ACT3622-20PCB is available at Aetrix Electronics and suitable for telecom line card interfacing, DSP co-processor data exchange, industrial PLC backplane interface, and test equipment pattern generation requiring stable component supply across extended production lifecycles.

Supply support for SN74ACT3622-20PCB 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 devices, with decades of experience in high-reliability timing and interface ICs.

SN74ACT3622-20PCB belongs to TI's ACT-family advanced CMOS logic portfolio, designed specifically for high-speed, low-power bidirectional data buffering in mixed-clock-domain systems such as communications infrastructure and real-time control.

FAQ

What is the maximum supported clock frequency for SN74ACT3622-20PCB?

The SN74ACT3622-20PCB supports clock frequencies up to 67 MHz on both CLKA and CLKB inputs. This specification is guaranteed across the full commercial temperature range (0°C to 70°C) and defines the upper limit for reliable read/write operation without violating setup/hold timing margins. Exceeding 67 MHz may result in metastability or data corruption, especially under asynchronous clock conditions.

How does the mailbox-bypass function work in SN74ACT3622-20PCB?

In SN74ACT3622-20PCB, the mailbox-bypass function uses two dedicated 36-bit registers (Mail1 and Mail2) with handshaking flags MBF1 and MBF2. Writing to Mail1 is triggered by CLKA edge with MBA high; reading from Mail1 is triggered by CLKB edge with MBB high. The SN74ACT3622-20PCB asserts MBF1 low on write and sets it high on successful read-enabling lock-free command passing independent of FIFO depth.

Can SN74ACT3622-20PCB operate with CLKA and CLKB running at different frequencies?

Yes, SN74ACT3622-20PCB is explicitly designed for asynchronous operation: CLKA and CLKB may run at different frequencies, phases, or duty cycles. All status flags (IRA/ORB/AFA/AEB etc.) are two-stage synchronized to their respective clocks, ensuring reliable flag assertion even under worst-case clock skew. No external synchronization circuitry is required.

What happens during power-up initialization of SN74ACT3622-20PCB?

Upon power-up, SN74ACT3622-20PCB requires explicit reset of both FIFOs: RST1 and RST2 must be asserted low for at least four CLKA and four CLKB rising edges. This initializes read/write pointers, forces IRA/IRB low and ORA/ORB low, and latches FS0/FS1 for flag offset selection. Failure to perform this sequence results in undefined FIFO behavior and potential data loss.

Is SN74ACT3622-20PCB pin-compatible with other members of the SN74ACT36xx family?

SN74ACT3622-20PCB is pin-to-pin compatible with SN74ACT3632-20PCB and SN74ACT3642-20PCB in the 120-pin PCB package. However, functional differences exist: SN74ACT3632 lacks mailbox registers entirely, while SN74ACT3642 implements mailbox logic with non-identical flag timing and reset behavior-requiring firmware validation before substitution.