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Texas Instruments SN74ALS648ADWRG4
- Part No.:
- SN74ALS648ADWRG4
- Manufacturer:
- Texas Instruments
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS648ADWRG4.pdf
- Description:
- IC TXRX INVERT 5.5V 24SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,499
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Product details
Overview
SN74ALS648ADWRG4 from Texas Instruments is an octal bus transceiver and register IC with 3-state inverting outputs, designed for bidirectional data flow control between two 8-bit buses (A and B). It features independent A/B registers, real-time or stored-data multiplexing via SAB/SBA controls, DIR-controlled direction, and OE-gated 3-state outputs. It operates at up to 40 MHz clock frequency with 5 V supply and is used in legacy industrial backplane and memory-mapped I/O systems requiring registered bus isolation.
For engineers reviewing the SN74ALS648ADWRG4 datasheet, SN74ALS648ADWRG4 pinout, SN74ALS648ADWRG4 application, or SN74ALS648ADWRG4 equivalent, key selection criteria include its inverting data path, dual-register storage capability, CLKAB/CLKBA edge-triggered latching, 3-state output drive strength (24 mA sink), and SOIC-24 package compatibility with legacy board layouts.
Technical Context
This device integrates eight identical bidirectional channels, each with D-type flip-flops for A and B bus data capture on low-to-high clock transitions (CLKAB for A→register, CLKBA for B→register). Its select-control logic (SAB/SBA) eliminates decoding glitches during real-time ↔ stored data switching.
Direction (DIR) determines bus assignment during transceiver mode; output-enable (OE) disables outputs while preserving input functionality for concurrent storage. The inverting output architecture means registered or transparent data appears inverted at B or A outputs depending on DIR and SAB/SBA state.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Octal bus transceiver with dual independent registers and 3-state inverting outputs |
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard TTL logic rails; not 3.3 V tolerant |
| Max Clock Frequency | 40 MHz - supports high-speed synchronous bus handshaking in legacy systems |
| Output Drive | 24 mA sink (IOL), 15 mA source (IOH) - sufficient for driving multiple TTL loads |
| Propagation Delay | 2–20 ns (A↔B path), 5–33 ns (clock-to-output) - enables sub-25 ns cycle timing |
| Operating Temperature | 0°C to 70°C - commercial-grade rating suitable for non-military embedded applications |
| Package | SOIC-24 (DW), 300-mil width - surface-mount compatible with automated assembly |
Pinout & Package
SN74ALS648ADWRG4 uses a 24-pin SOIC (DW) package with 300-mil body width and gull-wing leads. Pin numbering follows standard JEDEC SOIC convention (pin 1 top-left, counterclockwise).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | CLKAB | Clock input for latching data from A bus into A register on rising edge |
| 2 | SAB | Select A-B: controls multiplexing between real-time and stored A data on B bus |
| 3 | DIR | Direction control: low = B→A transfer, high = A→B transfer |
| 4–11 | A1–A8 | 8-bit data inputs/outputs for A-side bus (bidirectional, 3-state) |
| 12 | GND | Ground reference for all logic and I/O circuits |
| 13 | VCC | Positive supply (4.5–5.5 V); decoupling required near pin |
| 14–21 | B1–B8 | 8-bit data inputs/outputs for B-side bus (bidirectional, 3-state, inverting) |
| 22 | SBA | Select B-A: controls multiplexing between real-time and stored B data on A bus |
| 23 | CLKBA | Clock input for latching data from B bus into B register on rising edge |
| 24 | OE | Output enable: low = outputs active, high = all outputs high-impedance |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent registers | Enables simultaneous storage of A and B bus data without interference |
| Glitch-free select control | SAB/SBA logic prevents transient invalid states during real-time ↔ stored data switching |
| Inverting 3-state outputs | Provides signal inversion as part of transceiver function - eliminates external inverters |
| Input-enabled during output disable | A/B ports remain functional for data capture even when OE = high (isolation mode) |
| Real-time + stored data multiplexing | Supports four bus-management modes: transparent transfer, stored transfer, isolation, and dual storage |
Applications
| Industrial Backplane Interface | Legacy Memory-Mapped I/O |
|---|---|
Use Scenario: Isolating CPU address/data bus from peripheral expansion slots in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional registered transceiver managing synchronous data exchange between processor and field I/O modules. Use Value: Prevents bus contention during hot-swap events and enables deterministic timing via clocked register staging. |
Use Scenario: Interfacing microcontroller GPIO banks to external parallel peripherals (e.g., LCD controllers, ADCs) with shared address/data lines. IC Role / Device Role / Timing Role: Registered bus buffer providing level-shifted, direction-controlled, and glitch-free data routing. Use Value: Eliminates need for discrete latches and direction logic, reducing component count and layout complexity. |
| Test Equipment Bus Arbitration | Avionics Data Concentrator |
Use Scenario: Managing shared test bus access among multiple instrument modules in automated test systems. IC Role / Device Role / Timing Role: Controlled bus transceiver enabling time-sliced data injection and capture under system controller supervision. Use Value: Ensures deterministic arbitration using DIR/OE/CLK signals - no external arbitration logic required. |
Use Scenario: Aggregating sensor data from multiple analog/digital sources onto a central avionics data bus in certified airborne systems. IC Role / Device Role / Timing Role: Registered interface ensuring synchronized sampling and fault-isolated data forwarding. Use Value: Provides fail-safe isolation: OE high holds stored values while allowing continued input sampling for redundancy monitoring. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal registered transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS648A | Same functionality and pinout; G4 suffix denotes RoHS-compliant green packaging (halogen-free, matte tin lead finish) | No functional difference; identical electrical specs and timing - direct drop-in replacement where RoHS compliance is required | Select SN74ALS648A if RoHS/REACH compliance is mandatory; otherwise SN74ALS648ADWRG4 is functionally identical. |
| SN74AS648 | Faster propagation (2–9 ns vs. 3–33 ns), higher drive (48 mA sink), but higher ICC (120 mA vs. 88 mA) and stricter VIH/VIL thresholds | Requires tighter power delivery and noise margin control; unsuitable for mixed-ALS/AS systems without level-shifting | Choose SN74AS648 only when 90 MHz clock support and lower latency are critical; verify voltage margins and thermal design. |
Compared with SN74ALS648ADWRG4, SN74ALS648A offers identical performance with RoHS-compliant packaging, while SN74AS648 delivers significantly faster timing at the cost of higher power and stricter input voltage requirements - making it suitable only for high-performance upgrades with full system validation.
Availability
SN74ALS648ADWRG4 is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy memory-mapped I/O subsystems, and avionics data concentrators requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS648ADWRG4 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 founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
SN74ALS648ADWRG4 belongs to TI's legacy ALS (Advanced Low-Power Schottky) logic family, engineered for reliable operation in commercial-temperature industrial control and instrumentation systems with strict timing determinism.
FAQ
What is the primary function of SN74ALS648ADWRG4 in a digital system?
SN74ALS648ADWRG4 functions as an octal registered bus transceiver with inverting 3-state outputs. It enables bidirectional, clock-synchronized data transfer between two 8-bit buses (A and B), supporting both real-time pass-through and stored-data forwarding modes. Its dual independent registers allow concurrent capture of A and B bus data, making SN74ALS648ADWRG4 ideal for deterministic bus arbitration and isolation in industrial control systems.
Does SN74ALS648ADWRG4 support 3.3 V operation?
No, SN74ALS648ADWRG4 does not support 3.3 V operation. It is specified only for 4.5 V to 5.5 V supply voltage per its recommended operating conditions. Attempting to operate SN74ALS648ADWRG4 at 3.3 V will result in undefined logic levels, degraded noise margins, and potential failure to meet timing specifications - it is strictly a 5 V TTL-compatible device.
How does the inverting output behavior of SN74ALS648ADWRG4 affect system design?
SN74ALS648ADWRG4 provides inverting outputs on both A and B buses: data appearing at A1–A8 outputs is inverted relative to B1–B8 inputs (and vice versa), regardless of DIR or SAB/SBA state. This means system-level logic must account for inversion - either by inverting signals upstream/downstream or selecting complementary logic elsewhere in the data path. SN74ALS648ADWRG4's inverting nature is fixed and cannot be disabled.
Can SN74ALS648ADWRG4 replace SN74ALS646A in an existing design?
SN74ALS648ADWRG4 is not a direct replacement for SN74ALS646A due to functional differences: SN74ALS646A has true (non-inverting) outputs, while SN74ALS648ADWRG4 has inverting outputs. Swapping them requires verification of signal polarity across all eight channels and may necessitate logic inversion elsewhere. Electrical and pinout compatibility exists, but functional equivalence does not - SN74ALS648ADWRG4 must be selected intentionally for inversion requirements.
What is the meaning of the 'G4' suffix in SN74ALS648ADWRG4?
The 'G4' suffix in SN74ALS648ADWRG4 indicates Texas Instruments' green packaging standard: halogen-free, matte tin (Sn) lead finish, and RoHS-compliant materials. It does not denote a functional revision - SN74ALS648ADWRG4 is electrically and logically identical to SN74ALS648ADWR, differing only in environmental compliance and surface finish. The 'G4' marking ensures conformance with modern manufacturing and disposal regulations.
SN74ALS648ADWRG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Logic Type:
- Transceiver, Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 15mA, 24mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SOIC
SN74ALS648ADWRG4 FAQ
1.How can I place an order for SN74ALS648ADWRG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS648ADWRG4 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 SN74ALS648ADWRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS648ADWRG4 is usually 5 days.
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Once your SN74ALS648ADWRG4 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 SN74ALS648ADWRG4?
For technical support, including SN74ALS648ADWRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS648ADWRG4 requirements.
6.How does Aetrix verify that SN74ALS648ADWRG4 is sourced from the original manufacturer or authorized distributors?
All SN74ALS648ADWRG4 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 SN74ALS648ADWRG4 meets industry standards.
7.What is the process for return or replacement of SN74ALS648ADWRG4?
All SN74ALS648ADWRG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS648ADWRG4, 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 SN74ALS648ADWRG4 part is unused and in its original packaging.
Return procedure for SN74ALS648ADWRG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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