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Texas Instruments SN74LS623DW
- Part No.:
- SN74LS623DW
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74LS623DW.pdf
- Description:
- IC TXRX NON-INVERT 5.25V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,291
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Product details
Overview
SN74LS623DW from Texas Instruments is a dual 8-bit bus transceiver with 3-state outputs and independent output-enable control per port, designed for bidirectional data flow in TTL-level systems. It operates at VCC = 4.75–5.25 V, supports ±24 mA output drive, features typical propagation delay of 14 ns (A→B), and is rated for 0°C to 70°C ambient operation - commonly used in microprocessor address/data bus isolation and memory expansion interfaces.
For engineers reviewing the SN74LS623DW datasheet, SN74LS623DW pinout, SN74LS623DW application, or SN74LS623DW equivalent, key selection considerations include its dual-port 3-state architecture, TTL-compatible input thresholds, symmetric enable logic per side, and SOIC-20 package thermal and layout constraints.
Technical Context
The SN74LS623DW implements two independent 8-bit bidirectional transceivers (A↔B) with separate active-low output-enable inputs (1OE̅, 2OE̅) enabling selective port isolation. Each direction path includes TTL-compatible Schmitt-trigger inputs and totem-pole outputs capable of driving standard LS loads.
It uses bipolar TTL process technology, requires no external biasing, and maintains defined logic states during power-up/down via inherent input hysteresis and controlled output disable timing - critical for hot-swap-capable backplane and modular system designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.75 V to 5.25 V - ensures compatibility with standard TTL power rails and noise margin compliance. |
| Operating Temperature | 0°C to +70°C - specifies commercial-grade ambient range for non-extended industrial deployment. |
| Propagation Delay | 14 ns (A→B, typical) - determines maximum synchronous bus clock rate in buffered data paths. |
| Output Drive | ±24 mA (IOH/ IOL) - supports direct interfacing with multiple LS/TTL inputs without external buffering. |
| Input Hysteresis | Typical 0.3 V - provides noise immunity on shared control lines such as OE̅ in noisy board environments. |
| 3-State Leakage | ±10 µA (max) - guarantees high-impedance integrity when disabled, preventing bus contention leakage currents. |
Pinout & Package
SN74LS623DW is housed in a 20-pin SOIC (Small Outline Integrated Circuit) package with DW suffix, 0.300-inch body width, and standard JEDEC MS-013AC outline. Pin 1 is located in Quadrant 1 (Q1), with pin 10 as GND and pin 20 as VCC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1OE̅ / 2OE̅ | Active-low output-enable controls for Port A and Port B respectively - each independently disables its 8-bit output drivers. |
| 2–9 | A1–A8 | Port A bidirectional data terminals - connect to local subsystem (e.g., CPU address bus). |
| 11–18 | B1–B8 | Port B bidirectional data terminals - connect to remote subsystem (e.g., peripheral memory bank). |
| 10 | GND | Power ground reference - must be low-inductance connection to minimize switching noise coupling. |
| 20 | VCC | +5 V supply - requires local 0.1 µF ceramic decoupling adjacent to pin. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 8-bit transceivers | Enables simultaneous but isolated bidirectional data transfer between two domains without internal crosstalk. |
| Separate active-low OE̅ per port | Allows asymmetric bus arbitration - e.g., Port A enabled while Port B held high-Z during DMA cycles. |
| TTL-compatible input thresholds | VIH = 2.0 V min, VIL = 0.8 V max - ensures reliable logic recognition across legacy TTL and mixed-logic systems. |
| Matched propagation delays (A→B ≈ B→A) | 14 ns / 15 ns typical - supports deterministic timing closure in synchronous bidirectional protocols like IEEE-696. |
| SOIC-20 package with Q1 pin 1 | Standardized footprint compatible with automated placement and reflow processes; 1.27 mm pitch enables dense PCB routing. |
Applications
| Microprocessor Bus Isolation | Memory Expansion Interface |
|---|---|
Use Scenario: Isolating CPU address/data bus from peripheral expansion slots to prevent signal loading and timing skew. IC Role / Device Role / Timing Role: Bidirectional buffer with per-port enable control - manages direction and timing alignment between master and slave buses. Use Value: Enables clean bus segmentation while maintaining full 8-bit throughput and sub-15 ns latency per direction. | Use Scenario: Connecting additional RAM/ROM banks to an 8-bit microcontroller with limited native address space. IC Role / Device Role / Timing Role: Level-shifting and load-driving transceiver - translates and buffers control/address signals between controller and memory modules. Use Value: Supports up to 24 mA fan-out per line, eliminating need for discrete buffer arrays in memory-mapped I/O designs. |
| I/O Port Expansion | Legacy System Interfacing |
Use Scenario: Adding parallel I/O capability to microcontrollers lacking sufficient GPIO pins for industrial control panels. IC Role / Device Role / Timing Role: Configurable data conduit - direction set by software-controlled OE̅ lines, supporting both input capture and output drive modes. Use Value: Provides deterministic 8-bit parallel handshake timing with built-in hysteresis for pushbutton or relay feedback signals. | Use Scenario: Bridging modern FPGA-based controllers to vintage TTL peripherals (e.g., printers, disk controllers) requiring strict voltage and timing compliance. IC Role / Device Role / Timing Role: Protocol-transparent physical layer translator - preserves TTL logic levels and edge rates without protocol interpretation. Use Value: Eliminates level-shifter design complexity while meeting original equipment timing budgets (e.g., ISA bus setup/hold requirements). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS245N | Single 8-bit transceiver with directional control (DIR), not dual independent ports; no per-port OE̅. | Suitable only for unidirectional or single-direction-switched buses; lacks concurrent A/B arbitration capability. | Select when cost or board space favors simpler direction-control logic over dual-port flexibility. |
| SN74ALS623DW | Advanced LS version: lower power (19 mW vs. 48 mW), faster propagation (10 ns), tighter VIH/VIL specs. | Preferred in high-speed or power-constrained LS designs where timing margin is critical. | Choose for improved speed/power trade-off if existing SN74LS623DW layout accommodates same SOIC-20 footprint. |
Compared with SN74LS245N and SN74ALS623DW, the SN74LS623DW uniquely supports independent port enable control and matches legacy LS timing - making it optimal for field-replaceable upgrades in installed base systems requiring exact functional equivalence.
Availability
SN74LS623DW is available at Aetrix Electronics and suitable for microprocessor bus isolation, memory expansion interface, and legacy system interfacing requiring stable component supply and long-term obsolescence management.
Supply support for SN74LS623DW 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 company headquartered in Dallas, Texas, specializing in analog, embedded processing, and logic ICs for industrial, automotive, and communications markets.
The SN74LS623DW belongs to TI's legacy TTL logic family, engineered specifically for robust, pin-compatible replacement of earlier 74-series bus interface components in retrofitted and maintenance-critical systems.
FAQ
What is the function of the SN74LS623DW in a digital system?
The SN74LS623DW functions as a dual 8-bit bidirectional bus transceiver with independent 3-state control per port. It allows two 8-bit data buses to exchange information under software or hardware direction control, while isolating them when inactive. Its TTL-compatible inputs and ±24 mA outputs make it ideal for interfacing microprocessors with memory or peripherals. The SN74LS623DW is widely used where bus loading, timing predictability, and legacy compatibility are essential.
Does the SN74LS623DW support hot insertion or live bus swapping?
The SN74LS623DW does not include explicit hot-swap protection circuitry such as bus-hold or power-up 3-state. However, its inherent TTL input hysteresis (≈0.3 V) and controlled output-disable timing provide moderate noise immunity during transitional states. For true hot-swap operation, external current-limiting resistors and sequencing logic are recommended. The SN74LS623DW remains functional in modular backplane systems when combined with proper power-rail staging.
What are the key timing parameters of the SN74LS623DW?
Key timing parameters for the SN74LS623DW include typical propagation delay of 14 ns (A→B) and 15 ns (B→A), output enable/disable times of 12 ns and 10 ns respectively, and minimum pulse width of 15 ns on OE̅. These values are specified at VCC = 5 V, TA = 25°C, and with CL = 15 pF. The SN74LS623DW meets all timing requirements for standard 8-bit microprocessor buses operating up to 20 MHz effective data rates.
Can the SN74LS623DW replace the SN74LS245 in existing designs?
The SN74LS623DW cannot serve as a direct drop-in replacement for the SN74LS245 due to architectural differences: the SN74LS245 uses a single DIR pin for direction control, whereas the SN74LS623DW has two independent OE̅ pins and no DIR input. Board-level changes to enable logic and routing are required. However, the SN74LS623DW offers greater flexibility in systems needing concurrent bidirectional arbitration - a capability the SN74LS245 lacks.
What is the maximum capacitive load the SN74LS623DW can drive reliably?
The SN74LS623DW is characterized for operation with a 15 pF capacitive load, which aligns with standard TTL bus loading assumptions. While it can drive higher capacitance (e.g., up to ~40 pF) at reduced speed, signal integrity degrades beyond that point due to increased rise/fall times and potential ringing. For reliable operation across temperature and voltage extremes, keep trace + stub capacitance ≤15 pF per output line. The SN74LS623DW's ±24 mA drive strength helps maintain edge fidelity under these conditions.
SN74LS623DW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Logic Type:
- Transceiver, Non-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:
- 4.75V ~ 5.25V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74LS623DW FAQ
1.How can I place an order for SN74LS623DW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS623DW 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 SN74LS623DW reliable?
The price and inventory of SN74LS623DW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS623DW is usually 5 days.
3.What payment methods are accepted for SN74LS623DW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS623DW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS623DW?
SN74LS623DW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS623DW 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 SN74LS623DW?
For technical support, including SN74LS623DW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS623DW requirements.
6.How does Aetrix verify that SN74LS623DW is sourced from the original manufacturer or authorized distributors?
All SN74LS623DW 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 SN74LS623DW meets industry standards.
7.What is the process for return or replacement of SN74LS623DW?
All SN74LS623DW units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS623DW, 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 SN74LS623DW part is unused and in its original packaging.
Return procedure for SN74LS623DW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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