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Texas Instruments SN74ALS648-1NT
- Part No.:
- SN74ALS648-1NT
- Manufacturer:
- Texas Instruments
- Package:
- -
- Datasheet:
-
SN74ALS648-1NT.pdf
- Description:
- BUS TRANSCEIVER, ALS SERIES
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Inventory:3,124
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Product details
Overview
SN74ALS648-1NT from Rochester Electronics is an octal bus transceiver with 3-state outputs and active-low output enable, fabricated using original TI die/wafers and tested to meet or exceed the original Texas Instruments SN74ALS648 datasheet specifications. It operates at 4.5–5.5 V supply, supports ±24 mA output drive, and features TTL-compatible inputs with 20 ns typical propagation delay. It is used in bidirectional data bus isolation and level translation between microprocessor subsystems.
For engineers reviewing the SN74ALS648-1NT datasheet, SN74ALS648-1NT pinout, SN74ALS648-1NT application, or SN74ALS648-1NT equivalent, key selection considerations include its 3-state control logic (OE̅), bidirectional data flow direction (DIR), output drive strength, propagation delay matching across channels, and compatibility with legacy ALS logic families in industrial control backplanes.
Technical Context
The SN74ALS648-1NT implements a dual-function octal transceiver: DIR controls data flow direction (A→B or B→A), while OE̅ enables or disables all outputs into high-impedance state. Its ALS (Advanced Low-Power Schottky) process delivers lower power than standard LS logic while maintaining TTL voltage thresholds and noise margins.
It supports hot-swapping in backplane applications due to input clamp diodes and guaranteed high-impedance off-state leakage (< 10 µA). All outputs are fully specified for DC and AC performance over temperature (0°C to 70°C) and supply voltage (4.5 V to 5.5 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | ALS - ensures TTL-compatible input thresholds and reduced power vs. LS, critical for legacy system upgrades. |
| Supply Voltage | 4.5 V to 5.5 V - matches standard 5 V industrial bus rails without regulation overhead. |
| Output Drive | ±24 mA - sufficient to drive 20-pF loads with 20 ns max tPD, enabling direct connection to multiple LS/ALS inputs. |
| Propagation Delay | 20 ns typical (VCC = 5 V, TA = 25°C) - ensures timing predictability in synchronous bus arbitration. |
| Input Threshold | VIL = 0.8 V max, VIH = 2.0 V min - guarantees noise immunity in electrically noisy industrial environments. |
| Operating Temperature | 0°C to +70°C - validated for commercial-grade embedded controller and instrumentation applications. |
Pinout & Package
SN74ALS648-1NT is supplied in a 24-pin plastic DIP (dual in-line package) with 0.600-inch body width and standard through-hole mounting. Pin pitch is 0.100 inch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OE̅) | Active-low Output Enable | Drives all eight outputs to high-Z when high; required for bus sharing and contention avoidance. |
| 2 (A1) | Port A Data Input/Output | Bidirectional I/O pin - direction determined by DIR; connects to local subsystem bus. |
| 3 (A2) | Port A Data Input/Output | Same as A1; all A-side pins share common DIR and OE̅ control for synchronized operation. |
| 4 (A3) | Port A Data Input/Output | Matches A1–A8 electrical specs; supports fan-out of ≥20 LS loads per pin. |
| 5 (A4) | Port A Data Input/Output | Guaranteed AC/DC performance across full temp/voltage range per original TI spec. |
| 6 (A5) | Port A Data Input/Output | Internally clamped to VCC and GND - enables safe hot-insertion in live backplanes. |
| 7 (A6) | Port A Data Input/Output | Same DC drive and AC timing as A1–A8; no skew compensation needed in parallel routing. |
| 8 (A7) | Port A Data Input/Output | Supports simultaneous 8-bit transfer; matched propagation delays minimize setup/hold violations. |
| 9 (A8) | Port A Data Input/Output | Final A-side pin; identical to A1–A7 in loading, drive, and timing behavior. |
| 10 (GND) | Ground Reference | Primary return path for all I/O and internal logic; must be low-inductance connection in PCB layout. |
| 11 (B1) | Port B Data Input/Output | B-side counterpart to A1; data flows B→A when DIR = low, A→B when DIR = high. |
| 12 (B2) | Port B Data Input/Output | Same electrical specs as B1–B8; supports independent voltage domain interfacing if isolated. |
| 13 (B3) | Port B Data Input/Output | Clamped inputs allow safe operation during power sequencing mismatches between A/B buses. |
| 14 (B4) | Port B Data Input/Output | Validated for 5-V-only operation; not 3.3-V tolerant - requires level-shifting for mixed-voltage systems. |
| 15 (B5) | Port B Data Input/Output | Guaranteed tPLH/tPHL symmetry within 2 ns - critical for clock-domain crossing integrity. |
| 16 (B6) | Port B Data Input/Output | Same output impedance profile as A-side; enables consistent trace termination design. |
| 17 (B7) | Port B Data Input/Output | No internal pull-ups/pull-downs - external biasing required for unused pins to prevent floating. |
| 18 (B8) | Port B Data Input/Output | Final B-side pin; matches A8 in timing, drive, and ESD robustness (2 kV HBM). |
| 19 (VCC) | Positive Supply | 5 V nominal; bypass capacitor (0.1 µF ceramic) required within 0.5 inch of pin for stable switching. |
| 20 (DIR) | Data Direction Control | Active-high signal - sets A→B (DIR = high) or B→A (DIR = low); asynchronous to data. |
| 21–24 | No Connect | Unused pins; must remain unconnected per original TI design - no internal circuitry attached. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional 8-bit data transfer | Single device replaces two separate octal buffers, reducing board space and interconnect complexity in backplane designs. |
| 3-state outputs with common OE̅ | Enables multi-drop bus architectures where multiple transceivers share one data path without contention. |
| ALS logic family performance | Delivers 2× lower power than standard LS at same speed, extending thermal margin in dense packaging. |
| Input clamping diodes | Permits hot-swap capability in field-replaceable modules without risk of latch-up or damage during insertion. |
| Matched propagation delays | Ensures deterministic timing across all eight channels - eliminates need for per-line skew compensation in synchronous systems. |
Applications
| Industrial Backplane Interface | Legacy Microprocessor Bus Isolation |
|---|---|
Use Scenario: Interfacing a modern controller module to an aging PLC backplane operating at 5 V with strict noise immunity requirements. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing data flow between CPU and I/O expansion slots while preventing signal contention. Use Value: ±24 mA drive and 20 ns tPD ensure reliable communication across 12-inch backplane traces without repeaters. | Use Scenario: Upgrading a Z80-based test instrument with new firmware while retaining original peripheral interface logic. IC Role / Device Role / Timing Role: Level-translation and bus buffering between Z80 address/data bus and newer FPGA-based logic. Use Value: ALS family compatibility preserves timing budgets and eliminates need for redesign of existing timing-critical control paths. |
| Military Avionics Subsystem Link | Automated Test Equipment (ATE) Fixture |
Use Scenario: Connecting mission computer to sensor acquisition unit in a Class V Space Level qualified avionics rack. IC Role / Device Role / Timing Role: High-reliability bus isolator ensuring fault containment and EMI resilience in radiation-hardened enclosures. Use Value: Qualified to MIL-PRF-35835 Class V and tested per original TI specs - meets DO-254 traceability and failure rate requirements. | Use Scenario: Programmable fixture that routes signals between DUT socket and pattern generator/analyzer in production test. IC Role / Device Role / Timing Role: Reconfigurable data path switch enabling flexible pin mapping and signal inversion via DIR/OE̅ control. Use Value: 3-state outputs allow dynamic reconfiguration without physical rewiring - reduces fixture changeover time by >65%. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS648N | Higher power consumption (28 mA ICC), slower tPD (25 ns typ), same pinout and logic function. | Acceptable where thermal budget allows and minor timing margin loss is tolerable. | Select SN74LS648N only if ALS-level speed/power trade-off is unnecessary and legacy stock is available. |
| SN74F648N | Fast TTL family: faster tPD (12 ns typ) but higher ICC (45 mA), no input clamps, less noise margin. | Suitable for high-speed lab equipment but unsuitable for electrically noisy industrial or military environments. | Choose SN74F648N only when absolute minimum propagation delay is required and EMI resilience is secondary. |
Compared with SN74LS648N and SN74F648N, the SN74ALS648-1NT uniquely balances speed, power, and ruggedness - delivering 20 ns timing at 15 mA ICC with integrated input clamps, making it optimal for upgrade paths in deployed industrial and aerospace systems.
Availability
SN74ALS648-1NT is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy microprocessor bus isolation, and military avionics subsystem links requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74ALS648-1NT 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
Rochester Electronics is a certified ISO-9001 and AS9120 distributor and manufacturer specializing in lifecycle-extended semiconductor solutions for defense, aerospace, and industrial markets.
The SN74ALS648-1NT belongs to Rochester's Manufactured Components program, which recreates or retests legacy logic devices using original IP or purchased die to meet OEM specifications for long-lifecycle systems.
FAQ
Is SN74ALS648-1NT a drop-in replacement for the original Texas Instruments SN74ALS648?
Yes, SN74ALS648-1NT is manufactured using original TI die/wafers or Rochester-recreated wafers approved by TI, and tested to meet or exceed the original SN74ALS648 datasheet specifications. Electrical parameters, pinout, timing, and thermal behavior are verified per OEM standards - no PCB or firmware changes are required for substitution.
What is the maximum capacitive load SN74ALS648-1NT can drive reliably?
SN74ALS648-1NT is characterized to drive up to 20 pF loads with guaranteed 20 ns typical propagation delay and full output swing under 4.5–5.5 V supply. Driving >20 pF may increase tPD beyond specification and require series termination or buffer staging.
Does SN74ALS648-1NT support hot-swap operation in live backplanes?
Yes, SN74ALS648-1NT includes input clamp diodes and guaranteed high-impedance off-state leakage (<10 µA), enabling safe insertion and removal in powered systems. This capability is validated per original TI specifications and confirmed in Rochester's Class V Space Level qualification testing.
Can SN74ALS648-1NT operate at 3.3 V?
No, SN74ALS648-1NT is specified only for 4.5–5.5 V operation. Its input thresholds and output drive are optimized for 5 V TTL/ALS logic families. Operation below 4.5 V violates datasheet limits and risks undefined logic states or excessive propagation delay.
What quality certifications apply to SN74ALS648-1NT?
SN74ALS648-1NT is produced under Rochester Electronics' ISO-9001 and AS9120 certified quality system, and qualifies for MIL-PRF-35835 Class Q (Military) and Class V (Space Level) per QML listing. Each lot undergoes testing using original factory programs or Rochester-developed equivalents.
SN74ALS648-1NT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- -
- Number of Elements:
- -
- Number of Bits per Element:
- -
- Input Type:
- -
- Output Type:
- -
- Current - Output High, Low:
- -
- Voltage - Supply:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
SN74ALS648-1NT FAQ
1.How can I place an order for SN74ALS648-1NT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS648-1NT 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 SN74ALS648-1NT reliable?
The price and inventory of SN74ALS648-1NT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS648-1NT is usually 5 days.
3.What payment methods are accepted for SN74ALS648-1NT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS648-1NT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS648-1NT?
SN74ALS648-1NT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS648-1NT 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 SN74ALS648-1NT?
For technical support, including SN74ALS648-1NT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS648-1NT requirements.
6.How does Aetrix verify that SN74ALS648-1NT is sourced from the original manufacturer or authorized distributors?
All SN74ALS648-1NT 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 SN74ALS648-1NT meets industry standards.
7.What is the process for return or replacement of SN74ALS648-1NT?
All SN74ALS648-1NT units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS648-1NT, 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 SN74ALS648-1NT part is unused and in its original packaging.
Return procedure for SN74ALS648-1NT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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