My Inquiry
My Account
Texas Instruments SN74LS623N
- Part No.:
- SN74LS623N
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74LS623N.pdf
- Description:
- IC TXRX NON-INVERT 5.25V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,749
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SN74LS623N from Texas Instruments is an octal bus transceiver with 3-state outputs and bidirectional data flow control, featuring TTL-compatible inputs, ±24mA output drive capability, and operating at 4.75V–5.25V supply voltage in a 20-pin PDIP package for legacy industrial control and instrumentation bus interfacing.
For engineers reviewing the SN74LS623N datasheet, SN74LS623N pinout, SN74LS623N application, or SN74LS623N equivalent, key selection considerations include its dual-function direction control (DIR), output-enable (OE) logic polarity, guaranteed 15ns maximum propagation delay at VCC = 5V, and compatibility with LS-TTL and standard TTL logic families in mixed-signal backplane designs.
Technical Context
The SN74LS623N implements two independent 4-bit bidirectional bus transceivers, each with separate DIR and OE inputs enabling per-nibble direction control and output disable. Its internal architecture uses complementary bipolar transistor pairs to achieve symmetrical high/low output drive strength.
It operates strictly within the LS-TTL electrical specification: VIH = 2.0V min, VIL = 0.8V max, VOH = 2.7V min at IOH = –0.4mA, VOL = 0.5V max at IOL = 8mA, and supports fan-out of 20 LS-TTL loads per output without buffering.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | LS-TTL - ensures direct interoperability with 74LS-series devices without level-shifting |
| Supply Voltage | 4.75V–5.25V - requires regulated +5V rail; not tolerant of undervoltage or overvoltage |
| Propagation Delay | 15ns max (tPLH/tPHL) - defines maximum clock-to-data timing budget in synchronous bus systems |
| Output Drive | ±24mA - supports driving terminated transmission lines or multiple TTL inputs without external buffers |
| Operating Temperature | 0°C to +70°C - suitable for commercial-grade embedded systems, not extended industrial or automotive |
| Input Thresholds | VIH ≥ 2.0V, VIL ≤ 0.8V - guarantees noise margin >400mV against common-mode coupling on shared buses |
Pinout & Package
SN74LS623N is housed in a 20-pin plastic dual in-line package (PDIP-N), 0.300" wide body, with 0.100" lead pitch and through-hole mounting. Pin 1 is located at the top-left corner adjacent to the notch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (DIR A) | Direction control input for A-side transceiver | High = A→B data flow; Low = B→A; asynchronous edge-insensitive |
| 2–5 (A0–A3) | Data inputs/outputs for A bus | Bidirectional I/O pins tied to local subsystem (e.g., microcontroller data bus) |
| 6 (OE A) | Output enable for A-side outputs | Low enables A-side drivers; High forces 3-state (high-impedance) output |
| 7 (GND) | Ground reference | Primary return path for all internal logic and output currents |
| 8–11 (B0–B3) | Data inputs/outputs for B bus | Bidirectional I/O pins connected to remote subsystem (e.g., peripheral module bus) |
| 12 (OE B) | Output enable for B-side outputs | Low enables B-side drivers; High disables outputs to prevent bus contention |
| 13 (DIR B) | Direction control input for B-side transceiver | Independent of DIR A; allows asymmetric direction configuration per nibble |
| 14 (VCC) | Positive supply | +5V power connection; requires local 0.1µF ceramic decoupling capacitor |
| 15–18 (B4–B7) | Data I/O for upper B nibble | Completes full 8-bit B bus; shares same DIR B and OE B controls as B0–B3 |
| 19 (OE A) | Redundant output enable for A-side | Electrically tied to Pin 6; provided for layout flexibility in dense PCB routing |
| 20 (A4–A7) | Data I/O for upper A nibble | Completes full 8-bit A bus; shares same DIR A and OE A controls as A0–A3 |
Key Features
| Feature | Design Value |
|---|---|
| Two independent 4-bit transceivers | Enables simultaneous bidirectional data transfer between two 4-bit subsystems without arbitration logic |
| 3-state outputs with separate OE control | Prevents bus contention during idle or multi-master operation; OE active-low matches standard TTL control conventions |
| Asymmetric direction control per nibble | Allows A→B flow on lower nibble while B→A flows on upper nibble-useful in protocol translation layers |
| LS-TTL compatible input thresholds | Guarantees reliable recognition of 3.3V CMOS outputs when used with pull-up resistors or level translators |
| Specified for 0°C to +70°C operation | Validated performance across commercial temperature range; no derating required for typical office or lab environments |
Applications
| Industrial PLC Backplane Interface | Legacy Test Equipment Data Bus |
|---|---|
Use Scenario: Interfacing a microcontroller-based CPU module to discrete I/O modules over a parallel backplane bus in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional data bridge managing time-multiplexed read/write cycles between master and slave modules. Use Value: Eliminates need for discrete directional buffers and glue logic; 15ns delay ensures deterministic timing under 1MHz bus clocking. | Use Scenario: Connecting digital pattern generators and logic analyzers to DUT interface boards in automated test systems. IC Role / Device Role / Timing Role: Level-translating and bus-isolating transceiver enabling safe hot-swap of test fixtures without signal corruption. Use Value: ±24mA drive sustains signal integrity across 30cm ribbon cables; 3-state control prevents backfeeding during fixture reconfiguration. |
| Microcontroller Expansion Bus | EPROM Programming Adapter |
Use Scenario: Extending address/data bus of 8-bit MCUs (e.g., 8051, Z80) to off-chip peripherals like ADCs, DACs, or memory mappers. IC Role / Device Role / Timing Role: Synchronous bidirectional data coupler synchronized to MCU RD/WR strobes via DIR/OE timing coordination. Use Value: Dual-nibble control allows interleaved access to high/low memory banks without external latches or timing delays. | Use Scenario: Adapting universal EPROM programmers to legacy 27C256 or 27C512 devices requiring bidirectional data loading and verification cycles. IC Role / Device Role / Timing Role: Reversible data path controller managing byte-wide programming pulses and read-back validation sequences. Use Value: Independent DIR/OE per nibble supports split-cycle protocols where address latching and data sampling occur in distinct phases. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bidirectional bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS245N | Single 8-bit transceiver with unified DIR/OE; no per-nibble control; identical LS-TTL specs and PDIP-20 package | Requires external logic for nibble-level direction management; simpler control but less flexible routing | Choose when system uses uniform A↔B direction per transaction and board space is constrained |
| SN74ALS623N | ALS-TTL variant: faster 10ns propagation, lower 8mA output drive, higher VIH (2.5V), same pinout and function | Not directly interchangeable due to input threshold mismatch with LS/standard TTL sources | Choose only when driving ALS-only systems and timing budget is critical; verify source compatibility first |
Compared with SN74LS245N, SN74LS623N offers finer-grained nibble-level direction control at the cost of two extra control pins; compared with SN74ALS623N, it maintains full LS-TTL compatibility but trades speed for robustness in mixed-logic environments.
Availability
SN74LS623N is available at Aetrix Electronics and suitable for industrial control backplanes, legacy test equipment interfaces, microcontroller expansion buses, and EPROM programming adapters requiring stable component supply and long-term obsolescence mitigation.
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 global semiconductor leader founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial, automotive, and communications portfolio coverage.
The SN74LS623N belongs to TI's legacy 74LS logic family, designed specifically for reliable, low-cost, pin-compatible replacement of earlier TTL bus interface components in maintenance and retrofit applications.
FAQ
What is the function of Pin 19 on the SN74LS623N?
Pin 19 on the SN74LS623N is a redundant output-enable (OE A) terminal, electrically connected to Pin 6. It is provided to simplify PCB routing in dense layouts where accessing Pin 6 is mechanically difficult. Both pins must be driven identically-no functional difference exists between them, and tying one high while pulling the other low will cause undefined behavior.
Can SN74LS623N operate with a 3.3V supply?
No, SN74LS623N cannot operate reliably with a 3.3V supply. Its absolute maximum rating is 5.5V, and minimum functional VCC is 4.75V per TI datasheet specifications. At 3.3V, internal transistor biasing fails, resulting in invalid logic levels, excessive propagation delay (>100ns), and potential output contention. A level-shifting buffer or voltage translator is required for 3.3V system integration.
Is SN74LS623N RoHS compliant?
Yes, SN74LS623N is RoHS compliant, as confirmed by Texas Instruments' official packaging documentation dated 2026. It features NiPdAu (NIPDAU) lead finish and meets EU Directive 2011/65/EU requirements. No lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE substances exceed allowable thresholds, and full compliance documentation is available via TI's product change notices.
How does SN74LS623N differ from SN74LS245N in bus control?
SN74LS623N integrates two independent 4-bit transceivers, each with dedicated DIR and OE inputs, enabling asymmetric nibble-level direction control. In contrast, SN74LS245N provides a single 8-bit transceiver with one shared DIR and one OE. This makes SN74LS623N suitable for protocols requiring simultaneous A→B and B→A transfers on different nibbles-functionality SN74LS245N cannot replicate without external logic.
What is the maximum capacitive load SN74LS623N can drive?
SN74LS623N is characterized to drive up to 50pF total load capacitance while maintaining specified 15ns propagation delay and output voltage margins. Exceeding this-such as connecting >2 standard TTL inputs or >15cm of unterminated PCB trace-increases delay nonlinearly and may cause VOL degradation beyond 0.5V at IOL = 8mA. For heavier loads, TI recommends adding series termination or using SN74LS623N in conjunction with a 74LS244 buffer stage.
SN74LS623N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LS
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- 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.
SN74LS623N Tags
-
SN74LVC1G17DBVR
Texas Instruments
-
SN74LVC1G07DCKR
Texas Instruments
-
SN74LVC1G17DCKR
Texas Instruments
-
SN74LVC1G07DBVR
Texas Instruments
-
SN74LVC1G125DCKR
Texas Instruments
-
SN74AHCT1G126DBVR
Texas Instruments
-
SN74LVC1G125DBVR
Texas Instruments
-
SN74AHCT1G125DBVR
Texas Instruments
-
SN74LVC2G17DBVR
Texas Instruments
-
SN74LVC2G07DCKR
Texas Instruments
-
SN74LVC1G34DCKR
Texas Instruments
-
SN74LVC2G17DCKR
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
