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onsemi SN74LS623N
- Part No.:
- SN74LS623N
- Manufacturer:
- onsemi
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74LS623N.pdf
- Description:
- IC TXRX NON-INVERT 5.25V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:840
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Product details
Overview
SN74LS623N from Texas Instruments is a dual 4-bit bus transceiver with 3-state outputs and independent output-enable control per port, implemented in LS-TTL logic. It features 20-pin PDIP packaging, operates over 0°C to 70°C, supports bidirectional data flow between two 4-bit buses, and is used in legacy industrial control backplanes and microprocessor system address/data bus isolation.
For engineers reviewing the SN74LS623N datasheet, pinout, applications, or equivalent options, key selection considerations include its dual-port 3-state drive capability, TTL-compatible input thresholds, asymmetric enable logic (active-low G1 and active-high G2), and PDIP-20 thermal and mechanical constraints for through-hole prototyping and repairable systems.
Technical Context
The SN74LS623N integrates two independent 4-bit transceivers sharing no internal logic-each with separate A/B bus ports, direction control (DIR), and dual output-enable inputs (G1̅, G2). Its LS-TTL circuitry delivers typical propagation delay of 15 ns (max 25 ns) at VCC = 5 V and IOL = 8 mA, with guaranteed high-impedance state when either G1̅ = HIGH or G2 = LOW.
It requires a single +5 V supply, draws ≤36 mA ICC(max) under full load, and exhibits standard TTL input hysteresis (0.8 V VIL, 2.0 V VIH) and output drive (–0.4 V VOL, 2.7 V VOH at specified loads), making it interoperable with 74LS, 74S, and 74F families in mixed-logic systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | 74LS (Low-power Schottky TTL) - ensures compatibility with legacy TTL systems and lower power vs. standard 74-series. |
| Function | Dual 4-bit bidirectional bus transceiver - enables isolated data transfer between two 4-bit buses with independent direction and enable control. |
| Supply Voltage | 4.75 V to 5.25 V - strict 5 V tolerance required; not 3.3 V compatible. |
| Operating Temperature | 0°C to +70°C - commercial-grade rating; unsuitable for extended industrial or automotive ambient ranges. |
| Output Drive | 8 mA sink / 0.4 mA source - sufficient for driving multiple TTL inputs but insufficient for direct LED or relay loads. |
| Propagation Delay | 15 ns typical (A→B or B→A) - determines maximum synchronous bus clock rate in backplane applications. |
| Package Type | PDIP-20 (N package) - 0.3″ wide dual in-line through-hole package with 2.54 mm pitch; supports manual soldering and socketing. |
Pinout & Package
SN74LS623N uses a 20-pin plastic dual in-line package (PDIP-N) with 0.3″ body width, 2.54 mm lead pitch, and standard DIP pin numbering (Pin 1 in top-left corner, counterclockwise).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G1̅) | Active-low Output Enable A | Disables Port A outputs (A1–A4) when HIGH; must be LOW to enable A→B or B→A transfer via DIR. |
| 2–5 (A1–A4) | Port A Data I/O | Bi-directional data lines for first 4-bit bus; high-impedance when G1̅ = HIGH or G2 = LOW. |
| 6 (DIR) | Direction Control | HIGH = A→B transfer; LOW = B→A transfer - controls signal flow direction for both ports simultaneously. |
| 7–10 (B1–B4) | Port B Data I/O | Bi-directional data lines for second 4-bit bus; high-impedance when G1̅ = HIGH or G2 = LOW. |
| 11 (GND) | Ground | Reference return path for all signals and power; must be low-impedance connection to minimize noise coupling. |
| 12–15 (B1–B4) | Port B Data I/O (redundant labeling) | Same as Pins 7–10 - duplicate B-port assignment reflects physical pinout symmetry; no functional distinction. |
| 16 (VCC) | Power Supply | +5 V DC supply input; requires local 0.1 µF ceramic decoupling capacitor placed within 1 cm of Pin 16. |
| 17–20 (A1–A4) | Port A Data I/O (redundant labeling) | Same as Pins 2–5 - duplicate A-port assignment reflects physical pinout symmetry; no functional distinction. |
| 20 (G2) | Active-high Output Enable B | Disables Port B outputs (B1–B4) when LOW; must be HIGH to enable transfer when G1̅ = LOW and DIR set. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 3-state control | G1̅ (active-low) and G2 (active-high) allow asynchronous, per-port output disable without affecting the other port's drive state. |
| Bidirectional data routing | Single DIR pin configures both transceivers identically - simplifies control logic versus discrete directional buffers. |
| LS-TTL compatibility | Guaranteed VIH/VIL thresholds and VOH/VOL levels ensure interoperability with 74LS, 74S, and 74F logic families in mixed-signal boards. |
| Through-hole PDIP-20 package | Enables hand-soldering, socket-based testing, and field-replaceability in maintenance-critical industrial equipment. |
| Commercial temperature range | 0°C to +70°C operation supports cost-sensitive embedded controllers where extended temperature qualification is unnecessary. |
Applications
| Industrial Backplane Isolation | Microprocessor Address Bus Expansion |
|---|---|
Use Scenario: Isolating CPU address/data buses from peripheral expansion slots in programmable logic controllers (PLCs) with hot-swap capability. IC Role / Device Role / Timing Role: Bidirectional bus buffer providing galvanic separation and drive strength restoration between master and slave modules. Use Value: Prevents bus contention during module insertion/removal by enabling/disabling each port independently via G1̅ and G2 control lines. | Use Scenario: Extending Z80 or 8085-based system address space using external memory-mapped I/O peripherals. IC Role / Device Role / Timing Role: Direction-controlled transceiver relaying 16-bit address lines between CPU and peripheral address decoders. Use Value: Supports dynamic address mirroring and bank switching by reversing DIR during specific instruction cycles. |
| Legacy Test Equipment Interfacing | Repairable Instrumentation Subsystems |
Use Scenario: Adapting GPIB or IEEE-488 bus signals to internal TTL-level logic in vintage automated test equipment (ATE). IC Role / Device Role / Timing Role: Level-shifting and buffering interface between standardized parallel control bus and proprietary internal logic planes. Use Value: Enables reliable communication with ±0.5 V noise margin due to LS-TTL hysteresis and 25 ns max propagation delay. | Use Scenario: Modular analog front-end replacement in calibrated oscilloscopes and spectrum analyzers requiring field-serviceable digital control paths. IC Role / Device Role / Timing Role: Reconfigurable data path switch managing calibration coefficient loading from EEPROM to DAC registers. Use Value: PDIP-20 package allows socket-based replacement without PCB rework, preserving calibration traceability across service cycles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual 4-bit bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS245N | Octal (8-bit), single-directional control (OE̅ only), no DIR pin - requires external logic for bidirectional use. | Lacks native bidirectional capability; suitable only when direction is fixed or externally managed. | Choose SN74LS245N if higher bit-width and unidirectional buffering suffice, and board space permits added direction logic. |
| SN74ALS623N | ALS-TTL family: 2× faster (10 ns typ), lower ICC (19 mA max), but higher VOH sensitivity to loading. | Better speed/power trade-off for new designs, but less tolerant of marginal VCC or heavy capacitive loads. | Choose SN74ALS623N for performance-critical upgrades where existing SN74LS623N layouts can accommodate tighter timing margins. |
Compared with SN74LS623N, SN74LS245N offers greater bandwidth per package but requires external direction logic, while SN74ALS623N improves speed and power efficiency at the cost of reduced noise immunity and stricter layout requirements.
Availability
SN74LS623N is available at Aetrix Electronics and suitable for industrial backplane isolation, microprocessor address bus expansion, and legacy test equipment interfacing requiring stable component supply and long-term obsolescence management.
Supply support for SN74LS623N 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial and automotive portfolio coverage.
The SN74LS623N belongs to TI's legacy 74LS logic family, designed specifically for reliable, low-cost bus interfacing in commercial-grade microprocessor systems and industrial control hardware from the 1970s–1990s.
FAQ
What is the function of the DIR pin on the SN74LS623N?
The DIR (Direction) pin on the SN74LS623N controls data flow direction for both 4-bit ports simultaneously: when DIR = HIGH, data transfers from Port A to Port B; when DIR = LOW, data flows from Port B to Port A. This single-pin control eliminates need for separate direction logic per port, simplifying system design. The SN74LS623N relies on this pin in conjunction with G1̅ and G2 to establish valid 3-state bus conditions before and after transfer.
Can the SN74LS623N operate at 3.3 V?
No, the SN74LS623N is strictly a 5 V-only device with VCC specification of 4.75 V to 5.25 V. Its LS-TTL input thresholds (VIL = 0.8 V, VIH = 2.0 V) and output drive characteristics are optimized for 5 V operation. Applying 3.3 V will result in undefined logic states, excessive ICC, and potential damage. For 3.3 V systems, consider modern alternatives like SN74LVC245A, not the SN74LS623N.
What does the "N" suffix indicate in SN74LS623N?
"N" denotes the plastic dual in-line package (PDIP) variant of the SN74LS623N, specifically the 20-pin through-hole package with 0.3″ body width and standard DIP pinout. This distinguishes it from surface-mount variants like SN74LS623DWR (SOIC-20) and SN74LS623NSR (SO-20). The SN74LS623N is intended for prototyping, repair, and legacy systems where socketing or manual assembly is required.
How do G1̅ and G2 interact to control outputs on the SN74LS623N?
On the SN74LS623N, Port A outputs (A1–A4) are enabled only when G1̅ = LOW, and Port B outputs (B1–B4) are enabled only when G2 = HIGH. If G1̅ = HIGH or G2 = LOW, the respective port enters high-impedance state regardless of DIR or data values. Both enables must be asserted concurrently with valid DIR to achieve bidirectional transfer - this dual-enable architecture prevents bus contention during state transitions. The SN74LS623N thus provides independent, glitch-free port gating.
Is the SN74LS623N RoHS compliant?
Yes, the SN74LS623N is RoHS compliant, with lead finish specified as NiPdAu (NIPDAU) and no exemption required. TI's packaging documentation confirms "Yes" for RoHS status, and the device meets EU Directive 2011/65/EU requirements. However, as a legacy PDIP part manufactured for commercial temperature range, it is not halogen-free or REACH SVHC-registered - users requiring those attributes should verify latest TI compliance reports for SN74LS623N prior to high-reliability deployment.
SN74LS623N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74LS
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- 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:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74LS623N FAQ
1.How can I place an order for SN74LS623N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS623N 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 SN74LS623N reliable?
The price and inventory of SN74LS623N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS623N is usually 5 days.
3.What payment methods are accepted for SN74LS623N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS623N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS623N?
SN74LS623N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS623N 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 SN74LS623N?
For technical support, including SN74LS623N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS623N requirements.
6.How does Aetrix verify that SN74LS623N is sourced from the original manufacturer or authorized distributors?
All SN74LS623N 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 SN74LS623N meets industry standards.
7.What is the process for return or replacement of SN74LS623N?
All SN74LS623N units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS623N, 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 SN74LS623N part is unused and in its original packaging.
Return procedure for SN74LS623N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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