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Home > Products > Integrated Circuits (ICs) > Logic > Buffers, Drivers, Receivers, Transceivers

Texas Instruments SN74ALS244CDB

Name: SN74ALS244CDB
Brand: Texas Instruments
SKU: SN74ALS244CDB
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74ALS244CDB

Manufacturer:: Texas Instruments

Category:: Buffers, Drivers, Receivers, Transceivers

Package:: 20-SSOP (0.209", 5.30mm Width)

Datasheet:: SN74ALS244CDB.pdf

Description:: PROTOTYPE

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Product details

Overview

SN74ALS244CDB from Texas Instruments is an octal non-inverting buffer/line driver with 3-state outputs, designed for memory address driving, bus interfacing, and clock distribution in TTL-compatible systems. It operates from 4.5 V to 5.5 V, delivers ±12 mA output drive (I_OL/I_OH), features pnp input structure for reduced DC loading, and supports 0°C to 70°C industrial temperature range.

For engineers reviewing the SN74ALS244CDB datasheet, SN74ALS244CDB pinout, SN74ALS244CDB application, or SN74ALS244CDB equivalent, this device is selected for high-density 3-state bus buffering where low input current, fast enable/disable timing (t_PZL = 24 ns max), and compatibility with legacy ALS logic families are critical.

Technical Context

The SN74ALS244CDB implements dual 4-bit non-inverting buffers, each with independent active-low 3-state output-enable (OE) inputs (1OE, 2OE). Its pnp input stage minimizes input current draw (I_IL = –0.1 mA max), reducing loading on upstream drivers. Output logic states follow standard positive-logic truth table: OE = L enables Y = A; OE = H forces high-impedance Z.

Propagation delays are asymmetric: t_PLH = 16 ns max and t_PHL = 10 ns max (V_CC = 4.5–5.5 V, C_L = 50 pF). Enable/disable timing dominates system-level performance - t_PZL = 24 ns and t_PHZ = 10 ns define bus release and acquisition windows critical for shared-data-path arbitration.

Key Specifications

Parameter	Value and Actual Design Meaning
Supply Voltage (V_CC)	4.5 V to 5.5 V - compatible with standard 5 V TTL rails; absolute max 7 V prevents damage during transient overvoltage.
Output Drive (I_OL/I_OH)	±12 mA - sufficient to drive 10 LS-TTL loads or 20 ALS loads; enables robust signal integrity on loaded buses.
Propagation Delay (t_PHL)	10 ns max - ensures sub-100 MHz bus operation when cascaded with matched receivers; measured at V_CC = 4.5–5.5 V, C_L = 50 pF.
3-State Disable Time (t_PZL)	24 ns max - defines minimum bus turnaround time before next driver asserts; critical for bidirectional data bus protocols.
Input Current (I_IL)	–0.1 mA max - pnp input reduces loading on preceding gates, allowing higher fanout without signal degradation.
Operating Temperature	0°C to 70°C - qualified for commercial/industrial embedded control, instrumentation, and legacy computing applications.
Package	SSOP-20 (DB) - 7.5 mm × 5.6 mm footprint with 0.65 mm pitch; optimized for space-constrained PCBs while maintaining hand-solderability.

Pinout & Package

SN74ALS244CDB uses a 20-pin Shrink Small Outline Package (SSOP-20, package code DB), measuring 7.5 mm × 5.6 mm with 0.65 mm lead pitch and maximum height of 2.0 mm. Pin 1 is located at the top-left corner adjacent to the index area, with leads arranged in two parallel rows.

Pin/Terminal	Circuit Role	Design Meaning
1, 19	1OE, 2OE	Active-low output-enable controls first and second buffer groups; asserted low enables respective Y outputs.
2, 4, 6, 8	1A1–1A4	Inputs to first 4-bit buffer group; non-inverting; pnp structure limits input current to ≤0.1 mA.
3, 5, 7, 9	2Y4–2Y1	Outputs from second 4-bit buffer group; 3-state capable; driven low/high or placed in high-Z per 2OE state.
11–14	1Y1–1Y4	Outputs from first 4-bit buffer group; electrically identical to 2Yx pins; share same V_CC/GND supply network.
15–18	2A4–2A1	Inputs to second 4-bit buffer group; functionally mirrored to 1A1–1A4; support independent bus segment control.
10, 20	GND, V_CC	Power reference and supply; decoupling capacitor placement near these pins minimizes switching noise coupling into logic paths.

Key Features

Feature	Design Value
3-State Outputs	Enables direct connection to shared data/address buses without external isolation; eliminates contention during multi-driver arbitration.
pnp Input Structure	Reduces input current to ≤0.1 mA, lowering loading on upstream drivers and increasing effective fanout in ALS/LS-TTL systems.
Independent OE Control	Dual OE inputs (1OE, 2OE) allow selective enabling of two 4-bit groups - supports partial bus updates or segmented memory addressing.
TTL-Compatible Thresholds	V_IL = 0.8 V max and V_VIH = 2.0 V min ensure reliable interfacing with standard 5 V TTL, ALS, and AS logic families.
Fast Enable/Disable	t_PHZ = 10 ns and t_PZL = 24 ns minimize bus turnaround latency - essential for high-throughput memory and peripheral interfaces.

Applications

Memory Address Buffering	Legacy Bus Interface
Use Scenario: Driving 20-bit address lines from a microprocessor to multiple memory ICs in an industrial PLC backplane. IC Role / Device Role / Timing Role: Non-inverting 3-state buffer isolating CPU address bus from memory modules; enables dynamic bank selection via OE control. Use Value: Prevents address bus contention during memory refresh cycles; pnp inputs reduce loading on CPU address pins by >80% vs. standard TTL.	Use Scenario: Interfacing an ISA-bus controller to legacy I/O expansion cards requiring strict 5 V TTL timing compliance. IC Role / Device Role / Timing Role: Bidirectional bus driver translating between controller and card-side data lines using synchronized OE strobes. Use Value: t_PZL = 24 ns ensures sub-40 ns bus release window - meets ISA specification for data hold time after cycle termination.
Clock Distribution	Industrial Control Backplane
Use Scenario: Distributing a 12 MHz system clock to eight synchronous peripherals in a factory automation rack. IC Role / Device Role / Timing Role: Low-skew buffer replicating clock signal with matched propagation delay across all eight outputs. Use Value: t_PHL/t_PLH variation < 6 ns ensures < 0.5% duty-cycle distortion at 12 MHz - maintains setup/hold margins for downstream flip-flops.	Use Scenario: Isolating sensor input lines and actuator command lines on a DIN-rail mounted programmable logic controller. IC Role / Device Role / Timing Role: Dual-group buffer separating analog front-end digitization signals from digital control outputs on shared PCB traces. Use Value: Independent 1OE/2OE allows simultaneous read/write operations without cross-talk; SSOP-20 footprint saves >35% board area vs. PDIP-20.

Memory Address Buffering

Legacy Bus Interface

Use Scenario: Driving 20-bit address lines from a microprocessor to multiple memory ICs in an industrial PLC backplane.

IC Role / Device Role / Timing Role: Non-inverting 3-state buffer isolating CPU address bus from memory modules; enables dynamic bank selection via OE control.

Use Value: Prevents address bus contention during memory refresh cycles; pnp inputs reduce loading on CPU address pins by >80% vs. standard TTL.

Use Scenario: Interfacing an ISA-bus controller to legacy I/O expansion cards requiring strict 5 V TTL timing compliance.

IC Role / Device Role / Timing Role: Bidirectional bus driver translating between controller and card-side data lines using synchronized OE strobes.

Use Value: t_PZL = 24 ns ensures sub-40 ns bus release window - meets ISA specification for data hold time after cycle termination.

Clock Distribution

Industrial Control Backplane

Use Scenario: Distributing a 12 MHz system clock to eight synchronous peripherals in a factory automation rack.

IC Role / Device Role / Timing Role: Low-skew buffer replicating clock signal with matched propagation delay across all eight outputs.

Use Value: t_PHL/t_PLH variation < 6 ns ensures < 0.5% duty-cycle distortion at 12 MHz - maintains setup/hold margins for downstream flip-flops.

Use Scenario: Isolating sensor input lines and actuator command lines on a DIN-rail mounted programmable logic controller.

IC Role / Device Role / Timing Role: Dual-group buffer separating analog front-end digitization signals from digital control outputs on shared PCB traces.

Use Value: Independent 1OE/2OE allows simultaneous read/write operations without cross-talk; SSOP-20 footprint saves >35% board area vs. PDIP-20.

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal 3-state buffer applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74ALS244CDWR	SOIC-20 (DW) package; identical electrical specs and pinout; 2.65 mm height vs. SSOP's 2.0 mm.	Preferred where board assembly uses standard SOIC footprints or reflow profiles optimized for wider pitch.	Select SN74ALS244CDWR if existing PCB layout uses SOIC-20 land pattern or thermal mass constraints favor DW over DB.
SN74AS244ADWR	Faster propagation (t_PHL = 6.2 ns max) and higher drive (I_OL = 48 mA), but increased ICC (60 mA vs. 24 mA) and cost.	Suitable for high-speed bus segments where timing margin is critical and power budget permits.	Choose SN74AS244ADWR only when t_PHL < 7 ns is required and system can accommodate +150% supply current and tighter layout tolerances.

Compared with SN74ALS244CDWR, SN74ALS244CDB offers 25% lower profile and 12% smaller footprint for space-constrained designs; versus SN74AS244ADWR, it trades 2.5× speed for 60% lower power and broader voltage-margin tolerance in legacy systems.

Availability

SN74ALS244CDB is available at Aetrix Electronics and suitable for memory address buffering, legacy bus interface, clock distribution, and industrial control backplane applications requiring stable component supply across long-lifecycle embedded programs.

Supply support for SN74ALS244CDB 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 industrial, automotive, and communications markets.

The SN74ALS244CDB belongs to TI's legacy ALS (Advanced Low-Power Schottky) logic family, engineered for high-speed, low-power 5 V TTL-compatible systems where reliability and backward compatibility outweigh cutting-edge performance.

FAQ

What is the maximum operating temperature for SN74ALS244CDB?

The SN74ALS244CDB is characterized for operation from 0°C to 70°C, meeting commercial and industrial temperature requirements. It does not support extended military-range operation (–55°C to 125°C) like the SN54ALS244C variant. This rating is verified per TI's SDAS142C datasheet revision August 1995 and applies to all SSOP-20 packaged versions including SN74ALS244CDBR.A.

Does SN74ALS244CDB support pin-compatible replacement with SN74ALS244CDWR?

Yes, SN74ALS244CDB and SN74ALS244CDWR share identical pinout, logic function, and electrical specifications - only the package differs (SSOP-20 vs. SOIC-20). Both use 20-pin dual-row layouts with matching signal assignments. However, mechanical compatibility requires verifying PCB land pattern, solder paste volume, and reflow profile due to differing pitch (0.65 mm vs. 1.27 mm) and body dimensions.

What is the recommended decoupling strategy for SN74ALS244CDB?

Place a 0.1 µF ceramic capacitor between V_CC (pin 20) and GND (pin 10) as close as possible to the SN74ALS244CDB package. For systems with multiple devices or high-frequency switching, add a 4.7 µF tantalum or aluminum electrolytic capacitor within 1 inch of the power rail entry point. This mitigates V_CC droop during simultaneous output transitions, ensuring VOH ≥ 2.4 V under I_OH = –12 mA load.

Can SN74ALS244CDB drive LS-TTL loads directly?

Yes, SN74ALS244CDB can drive up to 10 LS-TTL inputs per output, based on its guaranteed I_OL = 12 mA and I_OH = –12 mA ratings. This exceeds the LS-TTL input current requirements (I_IL = –0.4 mA, I_IH = 20 µA), providing 2× margin for voltage drop across trace resistance and ensuring VOL ≤ 0.4 V and VOH ≥ 2.4 V across temperature and supply variations.

Is there a -1 version of SN74ALS244CDB with higher output current?

No - the –1 suffix (e.g., SN74ALS244C-1DWR) denotes a variant rated for I_OL = 48 mA, but this version is only offered in SOIC (DW) and PDIP (N) packages, not SSOP (DB). The SN74ALS244CDB part number corresponds exclusively to the standard 12 mA output version, as confirmed by TI's Package Option Addendum and SDAS142C datasheet section "The -1 version of SN74ALS244C is identical…except that the recommended maximum IOL for the -1 version is 48 mA."

SN74ALS244CDB Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74ALS

Package/Case:: 20-SSOP (0.209", 5.30mm Width)

Packaging:: Bulk

Product Status:: Obsolete

Logic Type:: Buffer, Non-Inverting

Number of Elements:: 2

Number of Bits per Element:: 4

Input Type:: -

Output Type:: 3-State

Current - Output High, Low:: 15mA, 48mA

Voltage - Supply:: 4.5V ~ 5.5V

Operating Temperature:: 0°C ~ 70°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-SSOP

SN74ALS244CDB FAQ

1.How can I place an order for SN74ALS244CDB through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74ALS244CDB 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 SN74ALS244CDB reliable?

The price and inventory of SN74ALS244CDB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS244CDB is usually 5 days.

3.What payment methods are accepted for SN74ALS244CDB?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS244CDB transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74ALS244CDB?

SN74ALS244CDB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74ALS244CDB 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 SN74ALS244CDB?

For technical support, including SN74ALS244CDB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS244CDB requirements.

6.How does Aetrix verify that SN74ALS244CDB is sourced from the original manufacturer or authorized distributors?

All SN74ALS244CDB 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 SN74ALS244CDB meets industry standards.

7.What is the process for return or replacement of SN74ALS244CDB?

All SN74ALS244CDB units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS244CDB, 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 SN74ALS244CDB part is unused and in its original packaging.

Return procedure for SN74ALS244CDB:

1.Submit a request within 90 days.

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

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