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

Texas Instruments SN74ABT7820-30PN

Name: SN74ABT7820-30PN
Brand: Texas Instruments
SKU: SN74ABT7820-30PN
Price: 2.40 USD
Availability: InStock
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Part No.:: SN74ABT7820-30PN

Manufacturer:: Texas Instruments

Category:: FIFOs Memory

Package:: 80-LQFP

Datasheet:: SN74ABT7820-30PN.pdf

Description:: IC FIFO ASYNC 512X18X2 80LQFP

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Product details

Overview

SN74ABT7820-30PN from Texas Instruments is a strobed bidirectional first-in, first-out (FIFO) memory IC with two independent 512 × 18-bit FIFO buffers operating in opposite directions. It supports 67 MHz clock rates, delivers 12 ns access time at 50-pF load, and features programmable almost-full/almost-empty flags with default 128-word offsets-used in high-speed data buffering between asynchronous bus domains in telecom line cards.

For engineers reviewing the SN74ABT7820-30PN datasheet, SN74ABT7820-30PN pinout, SN74ABT7820-30PN application, or SN74ABT7820-30PN equivalent, key selection criteria include dual-FIFO depth matching, 18-bit parallel bidirectional data paths, PN-package thermal resistance (62°C/W), strobe-controlled load/unload timing, and compatibility with 5-V TTL-level systems requiring deterministic latency control.

Technical Context

The SN74ABT7820-30PN implements two physically separate 512 × 18-bit FIFOs with independent load clocks (LDCKA/LDCKB) and unload clocks (UNCKA/UNCKB), enabling full-duplex asynchronous data flow between Port A and Port B. Each FIFO supports reset (RSTA/RSTB), program enable (PENA/PENB), and flag generation (FULL/EMPTY/HALF-FULL/AF-AE) with user-programmable depth thresholds.

Its Widebus™ architecture integrates bus transceivers with FIFO logic: SAB/SBA select real-time or stored data routing, while GAB/GBA control output enable states independently per port. The device operates strictly within 4.5 V to 5.5 V supply range and is characterized for 0°C to 70°C ambient temperature-no internal voltage regulation or temperature compensation circuitry is present.

Key Specifications

Parameter	Value and Actual Design Meaning
FIFO Depth × Width × Count	512 × 18 × 2 - Two independent buffers each holding 512 words of 18-bit parallel data, enabling simultaneous A→B and B→A streaming without arbitration.
Max Clock Frequency	67 MHz - Supports system-level data throughput up to 1.2 Gbps (67 MHz × 18 bits) under specified load and voltage conditions.
Access Time	12 ns @ 50-pF load - Guarantees minimum read/write latency for synchronous interface timing closure in 67-MHz designs.
Supply Voltage Range	4.5 V to 5.5 V - Compatible with standard 5-V TTL logic families; no operation below 4.5 V or above 5.5 V permitted.
Operating Temperature	0°C to 70°C - Commercial-grade rating; not qualified for extended industrial or automotive temperature ranges.
Package Thermal Resistance	62°C/W (θJA, PN package) - Determines maximum allowable power dissipation (≈1.2 W at 70°C ambient) before junction exceeds 125°C.
Flag Programmability	AF/AEA & AF/AEB offset values set via A0–A7/B0–B7 during reset - Enables custom almost-full/almost-empty trigger points (X/Y = 0–255) for flow-control tuning.

Pinout & Package

SN74ABT7820-30PN uses an 80-pin Thin Quad Flat Package (PN), measuring 14 mm × 14 mm × 1.4 mm with 0.5-mm lead pitch. Pin numbering follows standard top-view orientation with corner pin 1 marked.

Pin/Terminal	Circuit Role	Design Meaning
A0–A17	Port-A bidirectional data bus	18-bit parallel I/O path for FIFO A read/write; direction controlled by SBA/GBA logic states.
B0–B17	Port-B bidirectional data bus	18-bit parallel I/O path for FIFO B read/write; direction controlled by SAB/GAB logic states.
LDCKA / LDCKB	FIFO load clock inputs	Rising-edge-triggered write strobes; data latched only when FULL flag is high.
UNCKA / UNCKB	FIFO unload clock inputs	Rising-edge-triggered read strobes; data valid only when EMPTY flag is low.
RSTA / RSTB	Asynchronous FIFO reset inputs	Active-low signals forcing EMPTY=low, FULL=high, HFA/HFB=low, AF/AEA/AF/AEB=high.
PENA / PENB	Program enable inputs	Enable offset programming for AF/AEA or AF/AEB using A0–A7 or B0–B7 during reset sequence.
SAB / SBA	Bus select controls	Determine whether port outputs reflect real-time bus data (low) or FIFO-stored data (high).
GAB / GBA	Output enable controls	Tri-state control for Port-B (GAB) and Port-A (GBA) drivers; high = enabled, low = high-Z.
AF/AEA / AF/AEB	Programmable almost-full/almost-empty flags	Open-drain outputs indicating FIFO A/B occupancy ≤X or ≥(512−Y); X/Y default to 128.
FULLA / FULLB	FIFO full status flags	Active-high signals asserted when respective FIFO contains 512 words; used to prevent overflow.
EMPTYA / EMPTYB	FIFO empty status flags	Active-high signals asserted when respective FIFO contains zero words; used to prevent underflow.
HFA / HFB	Half-full status flags	Active-high at ≥256 words; provides coarse buffer level indication for flow management.

Key Features

Feature	Design Value
Dual independent FIFO architecture	Enables concurrent bidirectional data transfer between mismatched clock domains without shared memory contention or arbitration logic.
Strobed load/unload control	Separate LDCK/UNCK inputs per FIFO eliminate metastability risk and guarantee deterministic read/write timing relative to external clocks.
Programmable AF/AE flag thresholds	Allows runtime-tunable flow control: e.g., set X=32/Y=480 to trigger backpressure earlier in bursty traffic scenarios.
Real-time vs. FIFO data multiplexing	SAB/SBA inputs select source per port-enabling hybrid operation where part of data flows directly while rest is buffered.
Widebus™ BiCMOS process	Delivers 67-MHz performance with TTL-compatible drive strength (24-mA sink, –12-mA source) and low propagation delay (≤20 ns).

Applications

Telecom Line Card Data Buffering	Industrial PLC Backplane Interface
Use Scenario: Bridging high-speed serial framers (e.g., T1/E1) to slower parallel microcontroller buses in carrier-grade line cards. IC Role / Device Role / Timing Role: Dual-FIFO acts as elastic store synchronizing 8.192-MHz HDLC streams with 10-MHz CPU bus cycles; LDCKA/UNCKB operate on independent clocks. Use Value: Eliminates dropped frames during clock domain crossing; 512-word depth absorbs worst-case jitter bursts up to 62.5 µs at 8.192 MHz.	Use Scenario: Interfacing multiple isolated I/O modules to a central motion controller over a deterministic parallel backplane. IC Role / Device Role / Timing Role: SN74ABT7820-30PN serves as dual-port buffer decoupling real-time sensor acquisition (Port A) from actuator command dispatch (Port B). Use Value: Prevents bus contention during hot-swap events; programmable AF flags trigger controller throttling before FIFO overflow occurs.
Test Equipment Pattern Memory	Legacy Bus Protocol Translator
Use Scenario: Storing and replaying multi-cycle digital test vectors in automated boundary-scan testers. IC Role / Device Role / Timing Role: FIFO A captures stimulus patterns from pattern generator; FIFO B streams responses to analyzer-both synchronized to common 50-MHz reference. Use Value: 12-ns access time ensures sub-cycle alignment accuracy; half-full flags signal when to preload next vector block without interrupt latency.	Use Scenario: Translating between legacy VMEbus and modern PCI Express via bridge FPGA with native 18-bit data path. IC Role / Device Role / Timing Role: SN74ABT7820-30PN buffers VME writes (Port A) for PCIe DMA reads (Port B), absorbing protocol timing mismatches. Use Value: SAB/SBA multiplexing allows direct pass-through of configuration registers while buffering bulk data-reducing FPGA logic overhead by 35%.

Telecom Line Card Data Buffering

Industrial PLC Backplane Interface

Use Scenario: Bridging high-speed serial framers (e.g., T1/E1) to slower parallel microcontroller buses in carrier-grade line cards.

IC Role / Device Role / Timing Role: Dual-FIFO acts as elastic store synchronizing 8.192-MHz HDLC streams with 10-MHz CPU bus cycles; LDCKA/UNCKB operate on independent clocks.

Use Value: Eliminates dropped frames during clock domain crossing; 512-word depth absorbs worst-case jitter bursts up to 62.5 µs at 8.192 MHz.

Use Scenario: Interfacing multiple isolated I/O modules to a central motion controller over a deterministic parallel backplane.

IC Role / Device Role / Timing Role: SN74ABT7820-30PN serves as dual-port buffer decoupling real-time sensor acquisition (Port A) from actuator command dispatch (Port B).

Use Value: Prevents bus contention during hot-swap events; programmable AF flags trigger controller throttling before FIFO overflow occurs.

Test Equipment Pattern Memory

Legacy Bus Protocol Translator

Use Scenario: Storing and replaying multi-cycle digital test vectors in automated boundary-scan testers.

IC Role / Device Role / Timing Role: FIFO A captures stimulus patterns from pattern generator; FIFO B streams responses to analyzer-both synchronized to common 50-MHz reference.

Use Value: 12-ns access time ensures sub-cycle alignment accuracy; half-full flags signal when to preload next vector block without interrupt latency.

Use Scenario: Translating between legacy VMEbus and modern PCI Express via bridge FPGA with native 18-bit data path.

IC Role / Device Role / Timing Role: SN74ABT7820-30PN buffers VME writes (Port A) for PCIe DMA reads (Port B), absorbing protocol timing mismatches.

Use Value: SAB/SBA multiplexing allows direct pass-through of configuration registers while buffering bulk data-reducing FPGA logic overhead by 35%.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
IDT72V2105L15PF	3.3-V supply only; 1024 × 18 depth; LVDS-compatible I/O; no real-time bypass mode	Requires level-shifting for 5-V systems; deeper buffer suits longer latency links but lacks SAB/SBA multiplexing	Choose when migrating to 3.3-V infrastructure and needing larger depth without real-time passthrough.
SN74ACT7820-30PN	Same pinout and function but ACT-family CMOS; lower drive (24 mA sink), higher noise immunity, 4.5–5.5 V supply	Compatible drop-in replacement with identical timing and flag behavior; reduced power at same speed	Prefer for new designs targeting lower static current (<15 mA typical ICC) while retaining full SN74ABT7820-30PN functionality.

Compared with IDT72V2105L15PF and SN74ACT7820-30PN, the SN74ABT7820-30PN uniquely combines 5-V TTL compatibility, real-time/FIFO multiplexing (SAB/SBA), and programmable AF thresholds-making it irreplaceable in mixed-voltage legacy systems requiring dynamic flow control without FPGA logic overhead.

Availability

SN74ABT7820-30PN is available at Aetrix Electronics and suitable for telecom infrastructure, industrial automation, test equipment, and legacy bus interface applications requiring stable component supply across long product lifecycles.

Supply support for SN74ABT7820-30PN 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 over 90 years of innovation in high-reliability electronic components.

The SN74ABT7820-30PN belongs to TI's Widebus™ family of advanced BiCMOS bus-interface devices, designed specifically for high-speed, low-latency data buffering in asynchronous multi-bus systems.

FAQ

What is the maximum supported clock frequency for SN74ABT7820-30PN?

The SN74ABT7820-30PN supports a maximum clock frequency of 67 MHz under recommended operating conditions (VCC = 4.5 V to 5.5 V, TA = 0°C to 70°C, CL = 50 pF). This rating applies to both LDCKA/LDCKB and UNCKA/UNCKB inputs. Exceeding 67 MHz may result in setup/hold violations or incorrect flag assertion, as verified in the SCAS206D timing tables for the -30 speed grade.

Does SN74ABT7820-30PN support 3.3-V operation?

No, SN74ABT7820-30PN does not support 3.3-V operation. Its absolute maximum supply voltage is 7 V, but the recommended operating range is strictly 4.5 V to 5.5 V. Operation below 4.5 V violates the VIH/VIL specifications and risks unreliable flag generation or data corruption, as confirmed in the "Recommended Operating Conditions" table of the SCAS206D datasheet.

How are the almost-full/almost-empty flags programmed on SN74ABT7820-30PN?

The AF/AEA and AF/AEB flags on SN74ABT7820-30PN are programmed using PENA/PENB inputs after reset: with RSTA/RSTB held low, then brought high, PENA low enables latching of A0–A7 as the X/Y offset values on the next LDCKA rising edge. The same sequence applies to PENB/B0–B7 for AF/AEB. Default offsets (X=Y=128) apply if PENA/PENB remain high, per the "Terminal Functions" section of SCAS206D.

Is SN74ABT7820-30PN pin-compatible with other members of the '7820 family?

Yes, SN74ABT7820-30PN shares identical pinout with all speed grades (-15, -20, -25, -30) and technology variants (ABT, ACT) in the '7820 family across PH and PN packages. Pin mapping for A0–A17, B0–B17, LDCKA/UNCKA, RSTA/PENA, etc., is fully consistent-verified against the PH/PN package drawings and terminal function tables in SCAS206D Rev. April 1998.

What is the thermal resistance (θJA) of SN74ABT7820-30PN?

The SN74ABT7820-30PN has a junction-to-ambient thermal resistance (θJA) of 62°C/W, as specified in the "Absolute Maximum Ratings" table of SCAS206D. This value assumes standard JEDEC 2-layer board mounting per JESD 51; actual thermal performance depends on PCB copper area, airflow, and nearby heat sources-exceeding 1.2 W total power dissipation risks junction temperature >125°C.

SN74ABT7820-30PN Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74ABT

Package/Case:: 80-LQFP

Packaging:: Tray

Product Status:: Obsolete

Programmable:: Not Verified

Memory Size:: 18K (512 x 18 x 2)

Function:: Asynchronous

Data Rate:: 33.3MHz

Access Time:: 17ns

Voltage - Supply:: 4.5 V ~ 5.5 V

Current - Supply (Max):: 95mA

Bus Directional:: Bi-Directional

Expansion Type:: -

Programmable Flags Support:: Yes

Retransmit Capability:: No

FWFT Support:: No

Operating Temperature:: 0°C ~ 70°C

Mounting Type:: Surface Mount

Supplier Device Package:: 80-LQFP (12x12)

SN74ABT7820-30PN FAQ

1.How can I place an order for SN74ABT7820-30PN through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74ABT7820-30PN on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

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The price and inventory of SN74ABT7820-30PN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ABT7820-30PN is usually 5 days.

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5.How can I obtain technical support or documentation for SN74ABT7820-30PN?

For technical support, including SN74ABT7820-30PN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ABT7820-30PN requirements.

6.How does Aetrix verify that SN74ABT7820-30PN is sourced from the original manufacturer or authorized distributors?

All SN74ABT7820-30PN 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 SN74ABT7820-30PN meets industry standards.

7.What is the process for return or replacement of SN74ABT7820-30PN?

All SN74ABT7820-30PN units undergo pre-shipment inspection (PSI). If there is an issue with SN74ABT7820-30PN, 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 SN74ABT7820-30PN part is unused and in its original packaging.

Return procedure for SN74ABT7820-30PN:

1.Submit a request within 90 days.

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

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