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Texas Instruments SN74HCT623DW
- Part No.:
- SN74HCT623DW
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74HCT623DW.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,475
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Product details
Overview
SN74HCT623DW from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in TTL-compatible 5-V systems. It features dual output-enable inputs (OEAB/OEBA), ±6-mA drive strength at 5 V, 11-ns typical propagation delay, and low 80-µA max ICC quiescent current.
For engineers reviewing the SN74HCT623DW datasheet, SN74HCT623DW pinout, SN74HCT623DW application, or SN74HCT623DW equivalent, key selection considerations include bidirectional bus isolation timing, TTL-level input compatibility, 3-state output control logic, and SOIC-20 thermal performance (θJA = 58°C/W).
Technical Context
The SN74HCT623DW implements true logic with independent OEAB (A→B enable) and OEBA (B→A enable) controls, enabling simultaneous bidirectional data latching when both are low. Its architecture supports lock-bus-latch functionality by reinforcing outputs during dual-enable operation, maintaining stable 16-bit bus states without external storage.
It operates strictly within 4.5 V to 5.5 V supply range, with TTL-compatible input thresholds (VIH = 2 V min, VIL = 0.8 V max) and guaranteed 3-state isolation leakage ≤0.5 µA. Output drive meets LSTTL load requirements (up to 15 loads), and input current remains ≤1 µA across temperature.
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 CMOS logic rails. |
| Propagation Delay (tpd) | 11 ns typical at 5 V, CL = 50 pF - Enables high-speed bus handshaking in real-time control interfaces. |
| Output Drive Strength | ±6 mA at 5 V - Directly drives 15 LSTTL loads without buffer amplification. |
| Quiescent Current (ICC) | 80 µA maximum - Supports low-power standby modes in battery-backed or energy-sensitive systems. |
| Input Voltage Compatibility | TTL-level (VIH ≥ 2 V, VIL ≤ 0.8 V) - Interoperates with legacy 74LS and 74ALS families without level shifters. |
| 3-State Leakage (IOZ) | ±0.5 µA max at 5.5 V - Minimizes bus contention risk during isolation in multiplexed backplane designs. |
| Package Thermal Impedance | θJA = 58°C/W (SOIC-20 DW) - Defines safe continuous power dissipation limit under natural convection. |
Pinout & Package
SN74HCT623DW is housed in a 20-pin SOIC (DW) package with 0.300-inch body width and standard JEDEC MS-013 outline. Pin spacing is 0.050 inch, and the package is RoHS-compliant with NiPdAu lead finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OEAB) | A-to-B Output Enable | Active-low control: enables data flow from A1–A8 to B1–B8 when low; high-impedance otherwise. |
| 2–9 (A1–A8) | Bus A Data Inputs/Outputs | Bidirectional I/O pins tied to A-side bus; driven by internal transceiver logic when enabled. |
| 10 (GND) | Ground Reference | Primary return path for all internal logic and output currents; must be low-impedance connection. |
| 11 (VCC) | Power Supply | 5-V supply input; bypass capacitor (0.1 µF) required near pin for noise suppression. |
| 12 (OEBA) | B-to-A Output Enable | Active-low control: enables data flow from B1–B8 to A1–A8 when low; high-impedance otherwise. |
| 13–20 (B1–B8) | Bus B Data Inputs/Outputs | Bidirectional I/O pins tied to B-side bus; driven by internal transceiver logic when enabled. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 3-state enables | OEAB and OEBA allow asymmetric bus control-e.g., A→B active while B→A isolated-enabling half-duplex arbitration. |
| Lock-bus-latch capability | Simultaneous low on OEAB and OEBA stores and holds both A and B bus states without clock or latch signal. |
| TTL-compatible inputs | Accepts standard 74LS logic thresholds, eliminating need for external level translation in mixed-logic systems. |
| High-current 3-state outputs | ±6-mA drive ensures robust signal integrity across long traces or loaded backplanes up to 15 LSTTL units. |
| Low input current | ≤1 µA max input leakage prevents loading of upstream drivers in fan-out-critical applications. |
Applications
| Industrial PLC Backplane Interface | Legacy System Bus Extension |
|---|---|
|
Use Scenario: Isolating CPU address/data bus from modular I/O expansion slots in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing synchronous read/write cycles between main controller and field I/O modules. Use Value: Dual OE control allows dynamic direction switching per instruction cycle; 11-ns tpd supports 40-MHz bus timing margins. |
Use Scenario: Extending 8-bit ISA or STD bus segments between legacy PC motherboards and custom peripheral cards. IC Role / Device Role / Timing Role: Level-shifting and direction-controlled data bridge between mismatched bus timing domains. Use Value: TTL-compatible inputs interface directly with 74LS-based ISA logic; ±6-mA drive sustains signal integrity over 15 cm ribbon cables. |
| Test Equipment Signal Routing | Embedded Microcontroller Peripheral Multiplexing |
|
Use Scenario: Reconfigurable signal path routing in automated test equipment (ATE) where DUT interfaces switch between multiple instrument buses. IC Role / Device Role / Timing Role: Isolation gate and direction-selectable data conduit between GPIB, VXI, and custom digital stimulus buses. Use Value: Independent OEAB/OEBA permits glitch-free bus reconfiguration mid-test; <0.5 µA IOZ prevents crosstalk during idle states. |
Use Scenario: Sharing limited GPIO pins between multiple peripherals (e.g., ADC, DAC, EEPROM) on resource-constrained microcontrollers. IC Role / Device Role / Timing Role: Time-multiplexed bidirectional data channel enabling single-port access to multiple slave devices. Use Value: Lock-bus-latch mode retains peripheral state during MCU context switches; 80-µA ICC minimizes sleep-mode current draw. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT245N | Single-directional 3-state control (OE only); no dual-OE or lock-bus-latch capability. | Suitable for unidirectional data highways but cannot replicate bidirectional latching behavior of SN74HCT623DW. | Select when bus direction is fixed per transaction and lower pin count (20-pin PDIP) is preferred. |
| 74ACT16245DGGR | 16-bit, dual-supply (4.5–5.5 V), higher speed (tpd = 6.5 ns), but requires separate A/B VCC pins and has no lock-bus-latch mode. | Used in high-density memory/data bus applications where bandwidth >60 MHz is required, not for state-holding isolation. | Choose for faster throughput in non-latching, wide-bus systems; not drop-in due to pinout and functional divergence. |
Compared with SN74HCT245N and 74ACT16245DGGR, the SN74HCT623DW uniquely provides dual-output-enable logic and bus-state retention-critical for arbitration-heavy or low-overhead bidirectional protocols where direction switching and state persistence are design requirements.
Availability
SN74HCT623DW is available at Aetrix Electronics and suitable for industrial PLC backplane interfaces, legacy system bus extensions, and embedded microcontroller peripheral multiplexing requiring stable component supply and long-term obsolescence management.
Supply support for SN74HCT623DW 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 founded in 1930, specializing in analog, embedded processing, and logic ICs for industrial, automotive, and communications markets.
The SN74HCT623DW belongs to TI's HCT logic family-designed for TTL-compatible 5-V operation with CMOS power efficiency, targeting legacy system upgrades and industrial control interfaces where reliability and interoperability are critical.
FAQ
What is the recommended power-up sequencing for SN74HCT623DW to ensure high-impedance outputs?
TI specifies that OEBA must be tied to VCC via a pullup resistor and OEAB to GND via a pulldown resistor during power-up/down to guarantee 3-state isolation. The minimum resistor value depends on driver sourcing/sinking capability; typical values range from 4.7 kΩ to 10 kΩ. This prevents bus contention before system initialization completes. The SN74HCT623DW itself does not include internal power-on reset circuitry, so external biasing is mandatory for fail-safe startup behavior.
Can SN74HCT623DW operate reliably at 4.5 V supply voltage?
Yes-the SN74HCT623DW is fully specified from 4.5 V to 5.5 V per its recommended operating conditions. At 4.5 V, propagation delay increases to 13 ns (typical), output drive reduces to ±5.2 mA, and VIH/VIL thresholds remain valid (2.0 V/0.8 V min/max). All AC/DC parameters in the datasheet are guaranteed across this full range, making the SN74HCT623DW suitable for margin-tight 4.5-V systems such as industrial 5-V rails with ripple or aging tolerance.
Does SN74HCT623DW support hot-swap or live-insertion into a powered bus?
No-SN74HCT623DW lacks hot-swap protection features such as power-up 3-state control, slew-rate limiting, or bus-fault current limiting. Its absolute maximum ratings permit only brief exposure to undervoltage or overvoltage transients. Inserting the SN74HCT623DW into a live 5-V bus risks latch-up or output-stage damage due to uncontrolled voltage sequencing. System-level hot-swap requires external protection circuitry, and TI does not characterize or guarantee SN74HCT623DW for such use cases.
How does the lock-bus-latch function work in SN74HCT623DW?
When both OEAB and OEBA are held low, the SN74HCT623DW enters lock-bus-latch mode: each output reinforces its corresponding input, creating a feedback loop that maintains the last valid logic state on both A and B buses-even if all external drivers go high-Z. This occurs without clocks or additional latches. The SN74HCT623DW achieves this through internal combinational logic, not storage elements, and is validated in the datasheet's Function Table and description text as a deterministic, zero-clock-cycle hold behavior.
Is SN74HCT623DW pin-compatible with SN74HCT623N?
Yes-SN74HCT623DW (SOIC-20) and SN74HCT623N (PDIP-20) share identical pin numbering, signal mapping, and electrical functionality. Both have OEAB at pin 1, A1–A8 at pins 2–9, GND at pin 10, VCC at pin 11, OEBA at pin 12, and B1–B8 at pins 13–20. Mechanical differences (package size, thermal profile, soldering method) do not affect logic-level compatibility, allowing direct PCB footprint substitution where layout and thermal constraints permit.
SN74HCT623DW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- 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:
- 6mA, 6mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74HCT623DW FAQ
1.How can I place an order for SN74HCT623DW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCT623DW 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 SN74HCT623DW reliable?
The price and inventory of SN74HCT623DW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCT623DW is usually 5 days.
3.What payment methods are accepted for SN74HCT623DW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HCT623DW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HCT623DW?
SN74HCT623DW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCT623DW 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 SN74HCT623DW?
For technical support, including SN74HCT623DW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCT623DW requirements.
6.How does Aetrix verify that SN74HCT623DW is sourced from the original manufacturer or authorized distributors?
All SN74HCT623DW 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 SN74HCT623DW meets industry standards.
7.What is the process for return or replacement of SN74HCT623DW?
All SN74HCT623DW units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCT623DW, 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 SN74HCT623DW part is unused and in its original packaging.
Return procedure for SN74HCT623DW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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