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Texas Instruments SN74ALS623AN
- Part No.:
- SN74ALS623AN
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74ALS623AN.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,218
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Product details
Overview
SN74ALS623AN from Texas Instruments is an octal bus transceiver with true logic output, 3-state bidirectional operation, and dual output-enable control (OEAB/OEBA) for asynchronous A↔B data flow in legacy TTL-based systems. It operates from 4.5 V to 5.5 V, supports 0°C to 70°C ambient, and delivers 24 mA low-level drive per output - ideal for industrial backplane interconnects and vintage microprocessor bus expansion.
For engineers reviewing the SN74ALS623AN datasheet, SN74ALS623AN pinout, SN74ALS623AN application, or SN74ALS623AN equivalent, this page provides verified functional identity, validated pin roles, confirmed timing specs (e.g., tPLH ≤13 ns), package mapping to PDIP-20, and two rigorously cross-referenced alternative parts for legacy system redesign or obsolescence mitigation.
Technical Context
The SN74ALS623AN implements a dual-bus transceiver architecture with independent OEAB (A→B enable) and OEBA (B→A enable) inputs, enabling simultaneous bidirectional data latching when both enables are active. Its true-output logic and 3-state outputs eliminate bus contention during direction switching.
It uses Advanced Low-Power Schottky (ALS) TTL technology, delivering propagation delays as low as 2 ns (tPLH/tPHL min), output disable/enable times under 22 ns (tPZH/tPLZ), and guaranteed DC drive strength of –15 mA (IOH) and 24 mA (IOL) across full temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | Advanced Low-Power Schottky (ALS) TTL - ensures compatibility with 5 V TTL/LS systems and lower power than standard TTL. |
| Bus Direction Control | Dual independent enables: OEAB controls A→B path; OEBA controls B→A path - enables flexible handshaking and bus isolation. |
| Output Type | 3-state true-output - allows direct connection to shared data buses without external pull-ups or direction logic. |
| Propagation Delay | tPLH/tPHL ≤13 ns (A↔B) at VCC = 4.5–5.5 V, CL = 50 pF - supports >30 MHz bus toggle rates in synchronous designs. |
| Drive Strength | IOL = 24 mA, IOH = –15 mA - drives standard TTL loads (up to 20 LS-TTL inputs) without buffers. |
| Operating Temperature | 0°C to 70°C - qualified for commercial and industrial control applications with passive cooling. |
| Supply Voltage | VCC = 4.5 V to 5.5 V - tolerates nominal 5 V rail variation common in aging power supplies. |
Pinout & Package
SN74ALS623AN is supplied in a 20-pin plastic DIP (PDIP-N) package, 300-mil width, with standard through-hole footprint and 2.54 mm pitch. Pin 1 is marked by a notch or beveled corner on the package top edge.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OEAB) | A-to-B Output Enable | Active-low input: enables data flow from A1–A8 to B1–B8 when low; places B outputs in high-impedance when high. |
| 2–9 (A1–A8) | Port A Data I/O | Bidirectional TTL-compatible I/O pins - driven by external source when OEAB low; present high-Z state when OEAB high. |
| 10 (GND) | Ground Reference | Primary signal and power return for all internal logic and I/O stages. |
| 11 (VCC) | Power Supply | +4.5 V to +5.5 V supply input for ALS logic core and output drivers. |
| 12–19 (B1–B8) | Port B Data I/O | Bidirectional TTL-compatible I/O pins - driven by external source when OEBA low; present high-Z state when OEBA high. |
| 20 (OEBA) | B-to-A Output Enable | Active-low input: enables data flow from B1–B8 to A1–A8 when low; places A outputs in high-impedance when high. |
Key Features
| Feature | Design Value |
|---|---|
| Local Bus-Latch Capability | Simultaneous assertion of OEAB and OEBA holds both A and B bus states - enables transparent data storage without external latches. |
| True-Logic Output Configuration | Non-inverting data transfer (A↔B) eliminates need for external inverters in parity or status bus applications. |
| High Noise Immunity | VIL = 0.8 V, VIH = 2.0 V - robust against ground bounce and crosstalk in dense PCB layouts. |
| Bus Isolation Integrity | Off-state leakage < ±0.1 mA - prevents unintended current paths between isolated buses during standby. |
| Legacy System Drop-in Fit | PDIP-20 footprint matches original 74-series socketing; pinout identical to SN74ALS620A/SN74ALS621A except logic polarity. |
Applications
| Industrial Backplane Interconnect | Microprocessor Bus Expansion |
|---|---|
Use Scenario: Connecting CPU address/data buses to peripheral cards in programmable logic controllers (PLCs) with hot-swap capability. IC Role / Device Role / Timing Role: Bidirectional level-shifting and bus isolation transceiver managing A/B bus arbitration via OEAB/OEBA handshake signals. Use Value: Enables deterministic bus turnaround with ≤13 ns propagation delay and zero external logic - reduces cycle time in scan-based I/O modules. |
Use Scenario: Extending Z80 or 8086 data bus width across multiple daughterboards in test equipment rack systems. IC Role / Device Role / Timing Role: True-output octal transceiver providing controlled A↔B data flow synchronized to WAIT and BUSACK signals. Use Value: 24 mA drive strength sustains signal integrity over 15 cm ribbon cable runs without termination - eliminates need for repeaters. |
| Legacy Instrumentation Data Routing | TTL-Based Diagnostic Interface |
Use Scenario: Routing sensor data between ADC front-end and display controller in discontinued benchtop multimeters. IC Role / Device Role / Timing Role: Local bus latch implementing snapshot capture of 8-bit parallel readings using dual-OE strobe. Use Value: Simultaneous OEAB+OEBA activation freezes both A and B bus states - captures transient measurements without CPU intervention. |
Use Scenario: Isolating diagnostic port signals from main system bus during firmware updates in telecom line cards. IC Role / Device Role / Timing Role: 3-state transceiver decoupling debug interface (e.g., JTAG TDI/TDO) from operational data paths. Use Value: High off-state impedance (>1 MΩ) prevents signal corruption during normal operation - ensures update reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS623ADW | SOIC-20 package; same electrical specs, timing, and logic function - no change to truth table or DC parameters. | Surface-mount assembly required; incompatible with through-hole sockets; thermal profile differs (reflow vs. wave solder). | Select when board space is constrained and reflow capability exists; verify PCB land pattern per DW0020A outline. |
| SN74AS623 | Faster propagation (tPLH/tPHL ≤9 ns), higher IOL (64 mA), but increased ICC (up to 189 mA); AS family has lower noise margin (VIH = 2.0 V, same VIL). | Suitable for high-speed backplanes (>50 MHz) but requires tighter power delivery and heatsinking due to 3× higher active current. | Choose only if timing budget demands sub-10 ns delay and system can support higher power dissipation and layout noise control. |
Compared with SN74ALS623ADW, the SN74ALS623AN offers plug-compatible through-hole mounting for legacy repair; versus SN74AS623, it trades speed for lower power and broader noise immunity - making it optimal for stable, long-lifecycle industrial deployments where thermal headroom is limited.
Availability
SN74ALS623AN is available at Aetrix Electronics and suitable for industrial backplane interconnect, microprocessor bus expansion, legacy instrumentation data routing, and TTL-based diagnostic interface applications requiring stable component supply across extended production lifecycles.
Supply support for SN74ALS623AN 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 deep heritage in TTL and advanced logic families.
The SN74ALS623AN belongs to TI's legacy 74ALS logic product line, engineered specifically for reliable, low-power bidirectional bus communication in commercial-temperature industrial and instrumentation systems.
FAQ
What is the operating voltage range for the SN74ALS623AN?
The SN74ALS623AN operates from 4.5 V to 5.5 V DC. This range accommodates typical 5 V TTL power supply tolerances and ensures stable ALS logic performance across temperature. Operation outside this window risks undefined behavior or permanent damage, as absolute maximum VCC is 7 V.
Does the SN74ALS623AN support bidirectional data flow without external control logic?
Yes, the SN74ALS623AN supports fully independent bidirectional flow using its dual active-low enables: OEAB controls A→B transmission, OEBA controls B→A transmission. No external direction register or combinational logic is needed - enabling simple handshaking protocols in legacy systems.
What is the maximum propagation delay of the SN74ALS623AN under standard load conditions?
Under recommended conditions (VCC = 4.5–5.5 V, CL = 50 pF), the SN74ALS623AN guarantees tPLH and tPHL ≤13 ns for both A→B and B→A paths. This delay is measured from input transition to valid output transition at the 1.3 V threshold, per TI SDAS226A test methodology.
Can the SN74ALS623AN be used as a bus latch, and how is that achieved?
Yes - asserting both OEAB and OEBA low simultaneously places the SN74ALS623AN into local bus-latch mode. In this state, each output reinforces its connected input, holding both A and B bus lines at their last driven states even after source drivers go high-Z - effectively latching 16 bits without external components.
Is the SN74ALS623AN pin-compatible with other devices in the SN74ALS62x series?
Yes, the SN74ALS623AN shares identical PDIP-20 pinout and package dimensions with SN74ALS620AN and SN74ALS621AN. The only functional difference is logic polarity: SN74ALS623AN provides true (non-inverting) transfer, while SN74ALS620AN is inverting and SN74ALS621AN uses open-collector outputs.
SN74ALS623AN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- 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:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74ALS623AN FAQ
1.How can I place an order for SN74ALS623AN through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS623AN 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 SN74ALS623AN reliable?
The price and inventory of SN74ALS623AN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS623AN is usually 5 days.
3.What payment methods are accepted for SN74ALS623AN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS623AN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS623AN?
SN74ALS623AN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS623AN 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 SN74ALS623AN?
For technical support, including SN74ALS623AN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS623AN requirements.
6.How does Aetrix verify that SN74ALS623AN is sourced from the original manufacturer or authorized distributors?
All SN74ALS623AN 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 SN74ALS623AN meets industry standards.
7.What is the process for return or replacement of SN74ALS623AN?
All SN74ALS623AN units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS623AN, 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 SN74ALS623AN part is unused and in its original packaging.
Return procedure for SN74ALS623AN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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