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Texas Instruments SN74ALS620ADW
- Part No.:
- SN74ALS620ADW
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS620ADW.pdf
- Description:
- IC TXRX INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,110
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Product details
Overview
SN74ALS620ADW from Texas Instruments is an octal bus transceiver with 3-state inverting outputs, designed for asynchronous bidirectional data transfer between A and B buses in TTL-compatible systems. It features dual output-enable controls (OEAB/OEBA), local bus-latch capability via simultaneous enable, and operates over 0°C to 70°C at 4.5–5.5 V supply. Used in legacy industrial backplanes and memory-mapped I/O interfaces where signal inversion and bus isolation are required.
For engineers reviewing the SN74ALS620ADW datasheet, SN74ALS620ADW pinout, SN74ALS620ADW application, or SN74ALS620ADW equivalent, key selection criteria include its inverting logic polarity, 24 mA low-level drive capability, 10 ns typical propagation delay (A↔B), SOIC-20 package compatibility, and support for bus-hold latching via concurrent OEAB/OEBA assertion.
Technical Context
The SN74ALS620ADW implements a dual-bus transceiver architecture with independent directional control: OEAB enables A→B transmission, OEBA enables B→A transmission. When both enables are active, the device enters bus-latch mode-outputs reinforce inputs, preserving bus states without external latching.
Its ALS (Advanced Low-Power Schottky) logic family delivers TTL-compatible voltage thresholds (VIH = 2 V, VIL = 0.8 V), 3-state output disable isolation, and guaranteed operation up to 5.5 V. The inverting function means A-bus inputs appear as complemented signals on the B-bus outputs, and vice versa-critical for polarity-sensitive bus arbitration schemes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | ALS (Advanced Low-Power Schottky) - ensures TTL compatibility, lower power than standard LS, and robust noise immunity in noisy industrial environments. |
| Output Type | 3-state inverting - allows bidirectional bus sharing with hardware-controlled direction and high-impedance isolation when disabled. |
| Supply Voltage | 4.5 V to 5.5 V - supports standard +5 V rail with ±10% tolerance; absolute max 7 V prevents damage during transient overvoltage events. |
| Propagation Delay | 2–10 ns (A↔B) - enables high-speed data handshaking in sub-100 ns timing-critical control paths like microprocessor address/data bus extensions. |
| Output Drive | IOL = 24 mA (min) - sufficient to drive 10+ TTL loads or terminate stubs in parallel bus topologies without external buffers. |
| Operating Temp | 0°C to 70°C - qualified for commercial/industrial ambient conditions; not rated for extended temperature or automotive use. |
| Input Thresholds | VIH = 2.0 V, VIL = 0.8 V - matches standard TTL logic levels, ensuring interoperability with 74LS, 74F, and microcontroller GPIOs. |
Pinout & Package
SN74ALS620ADW uses a 20-pin SOIC (DW) package, 7.5 mm wide, 12.83 mm long, 2.65 mm max height, with 1.27 mm pitch and NiPdAu lead finish. RoHS-compliant, MSL Level-1, tube-packaged (25 pcs).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OEAB) | Output Enable A→B | Active-low control: asserts A→B data path; high-impedance B-bus when high. |
| 2–9 (A1–A8) | A-bus inputs/outputs | Bidirectional I/O pins; driven by A-side sources or reflect B-bus state when OEBA active. |
| 10 (GND) | Ground reference | Primary return path for all internal logic and output currents; must be low-impedance for noise control. |
| 11–18 (B1–B8) | B-bus inputs/outputs | Bidirectional I/O pins; driven by B-side sources or reflect A-bus state when OEAB active. |
| 19 (OEBA) | Output Enable B→A | Active-low control: asserts B→A data path; high-impedance A-bus when high. |
| 20 (VCC) | Power supply | +5 V supply input; requires local 0.1 µF ceramic decoupling adjacent to pin for switching noise suppression. |
Key Features
| Feature | Design Value |
|---|---|
| Local bus-latch capability | Simultaneous assertion of OEAB and OEBA holds both A and B bus states indefinitely-eliminates need for external latch ICs in hold-mode applications. |
| Inverting logic polarity | Complementary data transfer ensures signal inversion across buses-required in legacy systems using inverted control/address signaling (e.g., certain Z80 or 8085 peripheral interfaces). |
| Dual independent enable inputs | OEAB and OEBA allow asymmetric bus control-e.g., A→B only while B remains isolated, enabling time-multiplexed bus arbitration without contention. |
| ALS process technology | Reduces power consumption vs. standard LS while maintaining speed-typical ICC = 33–47 mA (active), critical for dense backplane designs with thermal constraints. |
| TTL-compatible interface | Meets VIH/VIL, VOH/VOL, and IOL/IOH specs per JEDEC Std 7A-guarantees interoperability with 74LS, 74F, and 74AS families without level-shifting. |
Applications
| Industrial Backplane Interface | Legacy Microprocessor I/O Expansion |
|---|---|
|
Use Scenario: Isolating and extending parallel data/address buses between CPU module and peripheral cards in modular PLC chassis. IC Role / Device Role / Timing Role: Bidirectional bus transceiver providing direction-controlled data routing and bus-hold latching during interrupt acknowledge cycles. Use Value: Eliminates bus contention during hot-swap transitions and maintains stable bus states during microcode wait states-reducing system-level timing margin requirements. |
Use Scenario: Connecting Z80 CPU data bus to dual-port RAM and peripheral ASICs in retro-computing hardware restoration projects. IC Role / Device Role / Timing Role: Inverting transceiver enabling proper signal polarity alignment between Z80's non-inverted data bus and legacy peripherals requiring complemented handshake lines. Use Value: Matches native Z80 bus timing (10 ns tPHL/tPLH) and drive strength (24 mA IOL), avoiding added propagation delay from discrete inverters or level shifters. |
| Memory-Mapped Peripheral Bridge | Test Equipment Bus Arbitration |
|
Use Scenario: Interfacing 8-bit microcontroller GPIO ports to external 8-bit ADC/DAC chips with shared data lines and separate chip-select domains. IC Role / Device Role / Timing Role: Directionally controlled data conduit allowing MCU to read sensor data or write control words without bus conflicts. Use Value: 3-state isolation prevents back-driving during idle periods; OEAB/OEBA sequencing enables deterministic half-duplex communication in firmware-driven protocols. |
Use Scenario: Managing shared GPIB or IEEE-488 bus lines among multiple test instruments in automated calibration racks. IC Role / Device Role / Timing Role: Bus isolator and polarity adapter ensuring correct signal inversion for legacy instrument handshaking (e.g., NRFD, NDAC lines). Use Value: Simultaneous OEAB/OEBA activation latches bus state during instrument handoff-preventing glitches during master/slave transitions in multi-drop configurations. |
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 | True (non-inverting) logic output; otherwise identical pinout, timing, and electrical specs. | Used where bus polarity must be preserved (e.g., direct connection to non-inverting peripherals); not suitable for systems requiring signal inversion. | Select SN74ALS623ADW only if inverting behavior is undesirable-no PCB change needed, but firmware or logic design must accommodate non-inverted data flow. |
| SN74AS623DW | Faster propagation (1–9 ns vs. 2–10 ns), higher drive (IOL = 64 mA), AS (Advanced Schottky) family-higher power consumption (ICC up to 189 mA). | Targeted at high-speed test equipment or military systems needing tighter timing margins; not drop-in due to increased supply current and thermal load. | Choose SN74AS623DW only when sub-10 ns timing is mandatory and board-level power/thermal design accommodates +100% ICC increase. |
Compared with SN74ALS620ADW, SN74ALS623ADW provides identical functionality without inversion-ideal for polarity-sensitive interconnects-while SN74AS623DW trades higher power for 2× speed improvement, making it suitable only where timing dominates thermal and efficiency constraints.
Availability
SN74ALS620ADW is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy microprocessor I/O expansion, and memory-mapped peripheral bridging requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS620ADW 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 SN74ALS620ADW belongs to TI's legacy 74ALS logic family, engineered for high-reliability, TTL-compatible digital interfacing in commercial and industrial control systems where proven stability outweighs ultra-high speed.
FAQ
What logic polarity does the SN74ALS620ADW implement?
The SN74ALS620ADW implements inverting logic: data transmitted from A to B or B to A appears complemented at the destination bus. This is inherent to its design and cannot be configured. The SN74ALS620ADW datasheet confirms complementary bus codes in the functional description and truth table-critical for matching legacy system polarity requirements.
Can SN74ALS620ADW operate at 3.3 V supply?
No, SN74ALS620ADW is not specified for 3.3 V operation. Its recommended supply range is 4.5 V to 5.5 V, with absolute maximum VCC at 7 V. At 3.3 V, VIH/VIL thresholds and output drive fall outside specification-resulting in unreliable switching or failure to meet TTL input compatibility. Use SN74LVC623A for 3.3 V systems.
How does bus-latch mode work on the SN74ALS620ADW?
Bus-latch mode activates when both OEAB and OEBA are asserted (low). In this state, each output reinforces its corresponding input-so A1 drives B1 and B1 drives A1, creating a feedback loop that holds both buses at their last valid logic states. The SN74ALS620ADW maintains this latched condition as long as both enables remain active and no external driver overrides the bus.
Is SN74ALS620ADW pin-compatible with SN74ALS621ADW?
No, SN74ALS620ADW is not pin-compatible with SN74ALS621ADW. While both are 20-pin SOIC octal transceivers, SN74ALS621ADW has open-collector outputs and true (non-inverting) logic, requiring pull-up resistors and different control logic. Their pin functions differ: SN74ALS621ADW lacks 3-state control and uses different output-stage topology-PCB redesign is required for substitution.
What is the maximum capacitive load SN74ALS620ADW can drive reliably?
The SN74ALS620ADW is characterized for CL = 50 pF in switching specifications, with tPLH/tPHL tested under those conditions. Driving >50 pF increases propagation delay nonlinearly and may cause marginal timing in high-speed buses. For loads exceeding 50 pF, add series termination or buffer stages-do not rely on SN74ALS620ADW alone to meet setup/hold timing at elevated capacitance.
SN74ALS620ADW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- Transceiver, 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:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74ALS620ADW FAQ
1.How can I place an order for SN74ALS620ADW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS620ADW 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 SN74ALS620ADW reliable?
The price and inventory of SN74ALS620ADW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS620ADW is usually 5 days.
3.What payment methods are accepted for SN74ALS620ADW?
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4.How is shipping managed for SN74ALS620ADW?
SN74ALS620ADW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS620ADW 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 SN74ALS620ADW?
For technical support, including SN74ALS620ADW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS620ADW requirements.
6.How does Aetrix verify that SN74ALS620ADW is sourced from the original manufacturer or authorized distributors?
All SN74ALS620ADW 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 SN74ALS620ADW meets industry standards.
7.What is the process for return or replacement of SN74ALS620ADW?
All SN74ALS620ADW units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS620ADW, 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 SN74ALS620ADW part is unused and in its original packaging.
Return procedure for SN74ALS620ADW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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