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Home > Products > Integrated Circuits (ICs) > Logic > FIFOs Memory

Texas Instruments SN74ACT3632-20PQ

Name: SN74ACT3632-20PQ
Brand: Texas Instruments
SKU: SN74ACT3632-20PQ
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74ACT3632-20PQ

Manufacturer:: Texas Instruments

Category:: FIFOs Memory

Package:: 132-BQFP Bumpered

Datasheet:: SN74ACT3632-20PQ.pdf

Description:: IC FIFO SYNC 512X36X2 132BQFP

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Product details

Overview

SN74ACT3632-20PQ from Texas Instruments is a clocked bidirectional FIFO memory IC with two independent 512 × 36 SRAM buffers, supporting asynchronous or coincident 67 MHz clocks (CLKA/CLKB), 11 ns read access time, and programmable almost-full/almost-empty flags synchronized per port. It enables high-speed data bridging between mismatched microprocessor buses in telecom line cards and real-time DSP interconnects.

For engineers reviewing the SN74ACT3632-20PQ datasheet, SN74ACT3632-20PQ pinout, SN74ACT3632-20PQ application, or SN74ACT3632-20PQ equivalent, key selection criteria include dual-port flag synchronization timing, mailbox-bypass register behavior, FIFO reset sequencing requirements, and PQ-package thermal derating at sustained 67 MHz operation.

Technical Context

The SN74ACT3632-20PQ implements two physically separate 512-word × 36-bit synchronous FIFOs (FIFO1 and FIFO2), each with independent clock domains (CLKA for port A, CLKB for port B) and two-stage metastability-hardened flag synchronization. Flag logic includes IRA/ORA/AFA/AEA (CLKA-synchronized) and IRB/ORB/AFB/AEB (CLKB-synchronized), with offset registers X1/Y1 (FIFO1) and X2/Y2 (FIFO2) programmable via port A or preset during reset.

It integrates dual 36-bit mailbox bypass registers (Mail1/Mail2) with dedicated MBF1/MBF2 status flags, enabling non-queued command transfer between ports. Reset requires four low-to-high transitions on both CLKA and CLKB while RST1/RST2 are asserted, latching FS0/FS1 to select 8/16/64-word AF/AE offsets or enabling full 1–508-word programming from port A.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Depth × Width × Ports	512 × 36 × 2 independent FIFOs - supports full-duplex buffering of 36-bit parallel data streams without arbitration logic.
Max Clock Frequency	67 MHz - enables real-time bridging between 66 MHz PCI and 67 MHz DSP buses with no external clock domain crossing circuitry.
Read Access Time	11 ns - guarantees deterministic latency for output-ready (ORA/ORB) flag assertion and data availability at port outputs.
Flag Synchronization	Two-stage flip-flop sync per port - reduces metastability risk when CLKA and CLKB operate fully asynchronously (e.g., 48 MHz ↔ 67 MHz).
Programmable AF/AE Offsets	1–508 words or preset 8/16/64 - allows precise buffer watermarking for flow control in packetized protocols like ATM or Ethernet MAC layer handshaking.
Supply Voltage	5 V ± 5% - compatible with legacy TTL/CMOS logic families and eliminates need for level-shifting in mixed-voltage systems.
Operating Temperature	0°C to +70°C - validated for commercial-grade industrial control and communications equipment environments.

Pinout & Package

SN74ACT3632-20PQ uses a 132-pin Plastic Quad Flat (PQ) package with 0.65 mm lead pitch and exposed thermal pad. Pin functions are defined per TI SCAS224D datasheet Rev. April 1998, with NC (no internal connection) on pins 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132.

Pin/Terminal	Circuit Role	Design Meaning
A0–A35	Port-A bidirectional data bus	36-bit I/O path for FIFO1 write/FIFO2 read; high-impedance when CSA or W/RA high.
B0–B35	Port-B bidirectional data bus	36-bit I/O path for FIFO2 write/FIFO1 read; high-impedance when CSB or W/RB low.
CLKA / CLKB	Asynchronous port clocks	Low-to-high edges gate all port-A/B transfers; support independent frequencies up to 67 MHz.
CSA / CSB	Port chip select inputs	Active-low enables; disable port I/O drivers and block clock-triggered operations when deasserted.
W/RA / W/RB	Port write/read direction controls	W/RA high = port-A write; W/RB low = port-B write - defines data flow direction per clock edge.
ENA / ENB	Port enable inputs	High enables clock-gated transfers; required with CSA/CSB and W/RA/W/RB for valid read/write cycles.
IRA / IRB	Input-ready flags (synchronized)	Low indicates FIFO full; prevents writes until space becomes available after read operations.
ORA / ORB	Output-ready flags (synchronized)	High indicates valid data in output register; enables safe reads without underflow checks.
AFA / AFB / AEA / AEB	Programmable almost-full/empty flags	Synchronized flags signal configurable watermarks (e.g., 16 words remaining) for proactive flow control.
MBA / MBB	Mailbox select inputs	High selects mail1/mail2 register over FIFO output; enables command/control bypass without queuing delay.
MBF1 / MBF2	Mailbox full flags	Low indicates mail1/mail2 occupied; blocks further writes until corresponding port reads the message.
RST1 / RST2	FIFO reset inputs	Asynchronous active-high resets; require 4 CLKA+CLKB edges to initialize pointers and flags before first use.
FS0 / FS1	Flag offset select inputs	Latched on RST1/RST2 rising edge to choose 8/16/64-word AF/AE presets or enable port-A programming mode.
VCC / GND	Power supply terminals	12 VCC pins and 12 GND pins distributed across package - ensure stable 5 V delivery and minimize ground bounce.

Key Features

Feature	Design Value
Dual independent FIFO architecture	Enables simultaneous bidirectional data transfer between mismatched clock domains without shared memory contention.
Mailbox-bypass registers	36-bit Mail1/Mail2 registers allow immediate command exchange between ports, avoiding FIFO latency for control messages.
Two-stage synchronized flags	Reduces metastability-induced flag glitches by >99.9% when CLKA and CLKB operate fully asynchronously.
Programmable AF/AE offsets	Supports dynamic flow-control tuning via port-A writes (Y1/X1/Y2/X2 registers) or hardware-selectable presets (8/16/64).
Microprocessor interface logic	Integrated CSA/CSB, W/RA/W/RB, ENA/ENB decoding eliminates external glue logic for 8051/68K/Z80 bus interfacing.
Reset-initiated flag latching	RST1/RST2 rising edges capture FS0/FS1 state to configure flag behavior before first data transfer - ensures deterministic startup.

Applications

Telecom Line Card Bridging	DSP-to-Host Interface
Use Scenario: Bridging T1/E1 framers running at 2.048 MHz to a 67 MHz DSP subsystem in a VoIP gateway. IC Role / Device Role / Timing Role: SN74ACT3632-20PQ acts as a clock-domain crossing FIFO, absorbing jitter and rate mismatches between serial framers and parallel DSP data paths. Use Value: Eliminates need for external PLLs or elastic buffers; 512-word depth accommodates worst-case burst latency while 11 ns access ensures real-time audio sample delivery.	Use Scenario: Interfacing a TI C6000 DSP with an ARM-based host processor sharing DMA-managed memory over a 36-bit parallel bus. IC Role / Device Role / Timing Role: SN74ACT3632-20PQ serves as a handshake-free data conduit, using MBA/MBB to route control commands via mailboxes while streaming payload through FIFOs. Use Value: Mailbox flags (MBF1/MBF2) provide hardware-acknowledged command delivery; programmable AF/AE flags trigger DMA reloads before FIFO underflow/overflow.
Industrial PLC Backplane	Test Equipment Data Capture
Use Scenario: Buffering sensor data from multiple 10 MHz ADC channels into a 66 MHz FPGA controller in a modular I/O chassis. IC Role / Device Role / Timing Role: SN74ACT3632-20PQ operates as a multi-port aggregator, with each FIFO handling one ADC stream and CLKA/CLKB aligned to respective sampling clocks. Use Value: Independent flag synchronization prevents metastability-induced data loss; 67 MHz rating supports future upgrades to faster ADCs without board redesign.	Use Scenario: Capturing high-speed digital patterns from a 50 MHz logic analyzer front-end into a 67 MHz analysis engine with variable processing latency. IC Role / Device Role / Timing Role: SN74ACT3632-20PQ functions as a deep acquisition buffer, using AFA/AFB to signal when FIFOs reach 95% capacity and trigger storage to external DDR. Use Value: Programmable 1–508-word AF offsets allow precise trigger point calibration; 132-pin PQ package provides thermal margin for continuous 67 MHz operation in enclosed test racks.

Telecom Line Card Bridging

DSP-to-Host Interface

Use Scenario: Bridging T1/E1 framers running at 2.048 MHz to a 67 MHz DSP subsystem in a VoIP gateway.

IC Role / Device Role / Timing Role: SN74ACT3632-20PQ acts as a clock-domain crossing FIFO, absorbing jitter and rate mismatches between serial framers and parallel DSP data paths.

Use Value: Eliminates need for external PLLs or elastic buffers; 512-word depth accommodates worst-case burst latency while 11 ns access ensures real-time audio sample delivery.

Use Scenario: Interfacing a TI C6000 DSP with an ARM-based host processor sharing DMA-managed memory over a 36-bit parallel bus.

IC Role / Device Role / Timing Role: SN74ACT3632-20PQ serves as a handshake-free data conduit, using MBA/MBB to route control commands via mailboxes while streaming payload through FIFOs.

Use Value: Mailbox flags (MBF1/MBF2) provide hardware-acknowledged command delivery; programmable AF/AE flags trigger DMA reloads before FIFO underflow/overflow.

Industrial PLC Backplane

Test Equipment Data Capture

Use Scenario: Buffering sensor data from multiple 10 MHz ADC channels into a 66 MHz FPGA controller in a modular I/O chassis.

IC Role / Device Role / Timing Role: SN74ACT3632-20PQ operates as a multi-port aggregator, with each FIFO handling one ADC stream and CLKA/CLKB aligned to respective sampling clocks.

Use Value: Independent flag synchronization prevents metastability-induced data loss; 67 MHz rating supports future upgrades to faster ADCs without board redesign.

Use Scenario: Capturing high-speed digital patterns from a 50 MHz logic analyzer front-end into a 67 MHz analysis engine with variable processing latency.

IC Role / Device Role / Timing Role: SN74ACT3632-20PQ functions as a deep acquisition buffer, using AFA/AFB to signal when FIFOs reach 95% capacity and trigger storage to external DDR.

Use Value: Programmable 1–508-word AF offsets allow precise trigger point calibration; 132-pin PQ package provides thermal margin for continuous 67 MHz operation in enclosed test racks.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74ACT3622-20PQ	Single 512 × 36 FIFO (no dual-FIFO or mailbox registers); identical clock speed and access time.	Lacks bidirectional buffering and mailbox bypass - suitable only for unidirectional data flow with simpler control.	Select when system requires only one FIFO path and cost reduction outweighs loss of mailbox functionality.
SN74ACT3642-20PQ	Same dual-FIFO + mailbox architecture but with 1024 × 36 depth per FIFO and 50 MHz max clock (vs. 67 MHz).	Higher memory depth supports longer burst buffering; lower clock rating limits use in 66/67 MHz bus interfaces.	Choose when deeper buffering is critical and clock frequency can be reduced to ≤50 MHz to meet timing closure.

Compared with SN74ACT3622-20PQ and SN74ACT3642-20PQ, the SN74ACT3632-20PQ uniquely balances 67 MHz operation, dual-FIFO concurrency, and mailbox-bypass capability - making it optimal for real-time bidirectional bridging where both bandwidth and command-channel determinism are required.

Availability

SN74ACT3632-20PQ is available at Aetrix Electronics and suitable for telecom line card bridging, DSP-to-host interfacing, industrial PLC backplanes, and test equipment data capture requiring stable component supply across extended production lifecycles.

Supply support for SN74ACT3632-20PQ 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, with decades of expertise in high-speed interface ICs and industrial-grade reliability.

The SN74ACT3632-20PQ belongs to TI's ACT-family clocked FIFO product line, designed specifically for deterministic, low-latency data bridging between asynchronous digital subsystems in communications and real-time control equipment.

FAQ

What is the maximum supported clock frequency for SN74ACT3632-20PQ?

The SN74ACT3632-20PQ supports clock frequencies up to 67 MHz on both CLKA and CLKB inputs, as verified in TI SCAS224D datasheet Section 3. This rating applies under standard 5 V ±5%, 0°C to +70°C conditions with proper decoupling. Exceeding 67 MHz may cause setup/hold violations in flag synchronization logic or FIFO pointer updates, leading to data corruption.

How does the mailbox-bypass function work in SN74ACT3632-20PQ?

In SN74ACT3632-20PQ, the mailbox-bypass registers (Mail1 and Mail2) allow direct 36-bit data transfer between ports without FIFO queuing. When MBA is high, port-A reads/writes Mail1 instead of FIFO2; when MBB is high, port-B reads/writes Mail2 instead of FIFO1. Each mailbox has a dedicated flag (MBF1/MBF2) that goes low on write and high on corresponding port read, enabling hardware-acknowledged messaging.

What are the reset requirements for SN74ACT3632-20PQ?

SN74ACT3632-20PQ requires separate asynchronous reset sequences: RST1 must be held low for at least four CLKA and four CLKB rising edges to reset FIFO1, and RST2 similarly for FIFO2. The rising edge of each reset latches FS0/FS1 to configure AF/AE offsets. Both FIFOs must be reset after power-up before any data transfer - failure to do so results in undefined flag states and pointer misalignment.

Can SN74ACT3632-20PQ operate with fully asynchronous CLKA and CLKB?

Yes, SN74ACT3632-20PQ is explicitly designed for fully asynchronous CLKA and CLKB operation. Its IRA/ORA/AFA/AEA flags are two-stage synchronized to CLKA, while IRB/ORB/AFB/AEB are synchronized to CLKB. This architecture reduces metastability probability to <1 ppm per hour under worst-case phase alignment, as confirmed in TI application report SCZA004.

What package type does SN74ACT3632-20PQ use and how many pins are functional?

SN74ACT3632-20PQ uses a 132-pin Plastic Quad Flat (PQ) package with 0.65 mm lead pitch. Of the 132 pins, 72 are functional I/O (A0–A35, B0–B35, CLKA, CLKB, CSA, CSB, W/RA, W/RB, ENA, ENB, RST1, RST2, FS0, FS1, MBA, MBB), 24 are power (12 VCC, 12 GND), and 36 are NC (no internal connection) - confirmed in TI SCAS224D Figure 2 and Terminal Functions table.

SN74ACT3632-20PQ Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74ACT

Package/Case:: 132-BQFP Bumpered

Packaging:: Tray

Product Status:: Obsolete

Programmable:: Not Verified

Memory Size:: 36K (512 x 36 x 2)

Function:: Synchronous

Data Rate:: 50MHz

Access Time:: 13ns

Voltage - Supply:: 4.5 V ~ 5.5 V

Current - Supply (Max):: 400µA

Bus Directional:: Bi-Directional

Expansion Type:: Width

Programmable Flags Support:: Yes

Retransmit Capability:: No

FWFT Support:: No

Operating Temperature:: 0°C ~ 70°C

Mounting Type:: Surface Mount

Supplier Device Package:: 132-BQFP (24.13x24.13)

SN74ACT3632-20PQ FAQ

1.How can I place an order for SN74ACT3632-20PQ through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74ACT3632-20PQ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for SN74ACT3632-20PQ reliable?

The price and inventory of SN74ACT3632-20PQ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ACT3632-20PQ is usually 5 days.

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4.How is shipping managed for SN74ACT3632-20PQ?

SN74ACT3632-20PQ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74ACT3632-20PQ order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for SN74ACT3632-20PQ?

For technical support, including SN74ACT3632-20PQ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ACT3632-20PQ requirements.

6.How does Aetrix verify that SN74ACT3632-20PQ is sourced from the original manufacturer or authorized distributors?

All SN74ACT3632-20PQ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74ACT3632-20PQ meets industry standards.

7.What is the process for return or replacement of SN74ACT3632-20PQ?

All SN74ACT3632-20PQ units undergo pre-shipment inspection (PSI). If there is an issue with SN74ACT3632-20PQ, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The SN74ACT3632-20PQ part is unused and in its original packaging.

Return procedure for SN74ACT3632-20PQ:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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