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Texas Instruments SN74BCT623NS
- Part No.:
- SN74BCT623NS
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74BCT623NS.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,410
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Product details
Overview
SN74BCT623NS from Texas Instruments is a dual-bus 8-bit transceiver with independent A→B and B→A direction control, designed for asynchronous data bus communication in 5-V TTL systems. It features true output logic, dual output-enable inputs (OEAB/OEBA), 128-mA low-level output drive on B port, and operates from 0°C to 70°C.
For engineers reviewing the SN74BCT623NS datasheet, SN74BCT623NS pinout, SN74BCT623NS application, or SN74BCT623NS equivalent, this page delivers verified electrical specs, functional timing behavior, package mapping to SO-20 (NS), isolation and bidirectional storage modes, and real-world substitution guidance for legacy TTL bus interface designs.
Technical Context
The SN74BCT623NS implements a BiCMOS architecture that reduces ICCZ quiescent current while maintaining TTL-compatible input thresholds (VIH = 2 V, VIL = 0.8 V) and driving capability. Its dual-enable logic supports four distinct operational states: A→B transmission, B→A transmission, full bus isolation, and simultaneous enable for data latching via bus-line reinforcement.
Switching performance is characterized under 50-pF load conditions, with tPLH/tPHL propagation delays ranging from 0.5 ns to 7.4 ns depending on direction and enable path. Output drive strength differs by port: B-port sinks up to 64 mA (IOL), while A-port sinks 24 mA - a design choice enabling asymmetric bus loading and termination flexibility.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures compatibility with standard 5-V TTL and mixed-voltage backplane systems. |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade industrial and computing equipment environments. |
| B-port Low-Level Output Current | 64 mA - enables direct drive of multiple TTL loads or termination resistors without external buffers. |
| A-port High-Level Output Voltage | 2.4 V min at IOH = −3 mA - guarantees robust noise margin against TTL VIH threshold (2 V). |
| Propagation Delay (A→B) | 0.5 ns (min) to 5.2 ns (max) - supports high-speed synchronous bus handshaking in legacy controllers. |
| Quiescent Supply Current | 6 mA max (ICCZ) - BiCMOS optimization reduces power during bus-isolation mode. |
| ESD Protection | >2000 V per MIL-STD-883C Method 3015 - enhances reliability in manual handling and board-level assembly. |
Pinout & Package
SN74BCT623NS is supplied in a 20-pin plastic small-outline (SO) package with NS drawing, 0.300-inch body width, and gull-wing leads. Pin 1 is located at top-left corner with notch or index mark.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | OEBA | Output-enable for B→A data path; active-low control signal. |
| 2–9 | A1–A8 | Input/output terminals for A-side 8-bit bus; bidirectional I/O with TTL-compatible thresholds. |
| 10 | GND | Ground reference for all internal circuitry and I/O structures. |
| 11 | VCC | Positive supply terminal (4.5–5.5 V); powers BiCMOS output drivers and input buffers. |
| 12–19 | B1–B8 | Input/output terminals for B-side 8-bit bus; higher sink current (64 mA) than A port. |
| 20 | OEAB | Output-enable for A→B data path; active-low control signal, independent of OEBA. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent enable control | OEAB and OEBA allow selective activation of A→B or B→A paths - essential for arbitration in shared-bus microcontroller systems. |
| True output logic | Outputs reflect actual input logic state without inversion - eliminates need for external inverters in data path routing. |
| Bus-isolation mode | When both OEAB and OEBA are high, all 16 I/Os enter high-impedance state - prevents contention between master and slave peripherals. |
| Data latching capability | Simultaneous low on OEAB and OEBA causes outputs to reinforce inputs, holding last valid bus state without clock or latch signal. |
| TTL-compatible input thresholds | VIH = 2 V / VIL = 0.8 V - ensures interoperability with legacy 74LS, 74ALS, and other bipolar TTL families. |
Applications
| Industrial Backplane Interface | Legacy Microcontroller Bus Expansion |
|---|---|
|
Use Scenario: Connecting an 8-bit microcontroller data bus to a parallel I/O expansion module across a 12-inch PCB backplane with stubs. IC Role / Device Role / Timing Role: Bidirectional level-translating transceiver managing A→B and B→A handshaking with independent enable timing. Use Value: 64-mA B-port drive compensates for capacitive loading on long traces; 5.2-ns max A→B delay preserves setup/hold margins at 10-MHz bus rates. |
Use Scenario: Adding external RAM or peripheral ICs to an 8051-based control system using discrete address/data multiplexing. IC Role / Device Role / Timing Role: Isolating CPU data bus from peripheral bus during wait-state insertion and enabling transparent read/write cycles. Use Value: Dual-OE logic allows precise control over bus ownership transitions; high-impedance isolation prevents data corruption during reset or interrupt servicing. |
| Test Equipment Data Capture | Automated Test Fixture Interface |
|
Use Scenario: Capturing parallel digital signals from DUTs in boundary-scan-less production test fixtures with limited FPGA I/O. IC Role / Device Role / Timing Role: Synchronizing and buffering 8-bit status or measurement data from DUT into controller FIFO with minimal skew. Use Value: Matched tPLH/tPHL delays (≤7.4 ns) ensure deterministic sampling window alignment; BiCMOS low ICCZ reduces fixture standby power. |
Use Scenario: Interfacing programmable logic controllers (PLCs) with custom sensor interface cards requiring bidirectional register access. IC Role / Device Role / Timing Role: Acting as configurable bus gate between PLC data bus and sensor card's local memory-mapped registers. Use Value: Simultaneous OEAB/OEBA enable provides nonvolatile bus hold during PLC firmware updates - maintains sensor state without external latches. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT623N | AC-family CMOS; 4.5–5.5 V supply; lower ICCZ (2 mA), but reduced drive (24 mA B-port), no BiCMOS speed advantage. | Lower power consumption, but insufficient for driving terminated 50-Ω buses or multiple TTL loads. | Choose SN74ACT623N only when power budget is critical and bus loading is light (≤2 TTL units). |
| 74F623N | Fast TTL family; identical pinout and function; higher ICC (92 mA typical), no ESD rating >2000 V, obsolete packaging. | Compatible timing and logic, but lacks modern ESD hardening and BiCMOS efficiency - unsuitable for new production. | Use 74F623N only for repair of legacy systems where SN74BCT623NS is unavailable and ESD risk is mitigated externally. |
Compared with SN74ACT623N and 74F623N, the SN74BCT623NS uniquely balances high B-port drive (64 mA), low ICCZ (6 mA), and MIL-grade ESD protection - making it the only option among the three suitable for new designs requiring robustness, speed, and legacy TTL compatibility.
Availability
SN74BCT623NS is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy microcontroller bus expansion, test equipment data capture, automated test fixture interfaces, and embedded control subsystems requiring stable component supply across extended product lifecycles.
Supply support for SN74BCT623NS 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, delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74BCT623NS belongs to TI's BCT (Bipolar-CMOS Transceiver) logic family, engineered specifically to replace high-power TTL bus interfaces with improved speed, lower quiescent current, and enhanced ESD resilience in commercial-grade systems.
FAQ
What is the maximum operating temperature range for the SN74BCT623NS?
The SN74BCT623NS is characterized for operation from 0°C to 70°C - a commercial-grade temperature range suitable for indoor industrial controls, computing peripherals, and test instrumentation. This differs from the military-grade SN54BCT623, which operates from −55°C to 125°C. The SN74BCT623NS datasheet specifies absolute maximum junction temperature as 150°C, but sustained operation above 70°C ambient requires derating and thermal analysis. Always verify PCB layout and airflow in high-temperature enclosures before deployment.
Does the SN74BCT623NS support hot-swapping or live insertion?
The SN74BCT623NS does not include built-in hot-swap protection features such as power-on reset, slew-rate limiting, or undervoltage lockout. While its BiCMOS structure offers better immunity than pure bipolar TTL, the device is not rated for hot insertion per JEDEC JESD63. Applying VCC before or after signal voltages may cause latch-up or excessive current flow. For hot-swap applications, external protection circuitry - including series resistors, TVS diodes, and controlled power sequencing - must be implemented. TI recommends verifying stress limits in Section 2.1 of the SCBS020A datasheet before designing live-insertion systems.
Can the SN74BCT623NS be used with 3.3-V logic systems?
No - the SN74BCT623NS is strictly a 5-V TTL-compatible device. Its input thresholds (VIH = 2 V, VIL = 0.8 V) and output voltage levels (VOH ≥ 2.4 V at −3 mA) are specified only for VCC = 4.5–5.5 V. Driving its inputs directly from 3.3-V logic violates the minimum VIH requirement and risks unreliable switching. Likewise, connecting its 5-V outputs to 3.3-V inputs exceeds absolute maximum input voltage ratings (−0.5 V to 5.5 V) and may damage downstream components. Use level-shifting buffers like TXB0108 or discrete resistor dividers if interfacing with 3.3-V systems.
What happens when both OEAB and OEBA are low on the SN74BCT623NS?
When both OEAB and OEBA are low (active), the SN74BCT623NS enters bidirectional data transfer mode: A1–A8 drives B1–B8, and B1–B8 simultaneously drives A1–A8. In this configuration, each output reinforces its corresponding input - effectively creating a wired-OR bus-hold function. If all external drivers on both buses are in high-impedance state, the 16 lines retain their last logic states without external latches. This behavior is explicitly documented in the FUNCTION TABLE and logic diagram of the SN74BCT623NS datasheet (SCBS020A, page 2–1).
Is the SN74BCT623NS RoHS compliant and lead-free?
Yes - the SN74BCT623NS is RoHS compliant and lead-free. According to TI's Packaging Information Addendum (July 2015), the orderable device SN74BCT623NSR carries the "Green (RoHS & no Sb/Br)" eco-plan designation, with CU NIPDAU lead finish and Level-1 moisture sensitivity rating (unlimited floor life at ≤30°C/60% RH). The "NS" suffix denotes the SO-20 package variant, and TI confirms full compliance with EU Directive 2011/65/EU and China RoHS II. Always verify the date code and reel label on incoming reels to confirm Green compliance for your specific lot.
SN74BCT623NS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74BCT
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- 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:
- 3mA, 24mA; 15mA, 64mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74BCT623NS FAQ
1.How can I place an order for SN74BCT623NS through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74BCT623NS 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 SN74BCT623NS reliable?
The price and inventory of SN74BCT623NS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT623NS is usually 5 days.
3.What payment methods are accepted for SN74BCT623NS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74BCT623NS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74BCT623NS?
SN74BCT623NS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74BCT623NS 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 SN74BCT623NS?
For technical support, including SN74BCT623NS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT623NS requirements.
6.How does Aetrix verify that SN74BCT623NS is sourced from the original manufacturer or authorized distributors?
All SN74BCT623NS 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 SN74BCT623NS meets industry standards.
7.What is the process for return or replacement of SN74BCT623NS?
All SN74BCT623NS units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT623NS, 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 SN74BCT623NS part is unused and in its original packaging.
Return procedure for SN74BCT623NS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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