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onsemi DM74ALS640AN
- Part No.:
- DM74ALS640AN
- Manufacturer:
- onsemi
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
DM74ALS640AN.pdf
- Description:
- IC TRANSCEIVER INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,191
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Product details
Overview
DM74ALS640AN from Fairchild Semiconductor is an inverting octal bus transceiver in a 20-lead PDIP package, designed for asynchronous bidirectional data transfer between parallel busses. It supports 5V operation (4.5–5.5V), delivers ±24mA output drive, and features 1–11ns propagation delay at 50pF load-used in legacy industrial control backplanes and TTL-level system interconnects.
For engineers reviewing the DM74ALS640AN datasheet, pinout, applications, or equivalent options, key selection criteria include its inverting logic behavior, DIR/G dual-control architecture, guaranteed switching over 0°C to +70°C, and compatibility with standard 5V TTL bus loading requirements.
Technical Context
The DM74ALS640AN implements true bidirectional data flow via separate direction (DIR) and output enable (G) inputs, where G = LOW enables transmission and DIR determines A→B or B→A path. Its inverting transceiver function means each data bit passes through complementary logic before output.
All eight data channels share identical electrical characteristics: VOH ≥ 2.4V at IOH = −3mA, VOL ≤ 0.4V at IOL = 12mA, and tPLH/tPHL ≤ 11ns/10ns under VCC = 4.5–5.5V and CL = 50pF conditions-ensuring deterministic timing in synchronous bus arbitration schemes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5V to 5.5V - operates reliably across full TTL supply tolerance without regulation. |
| Propagation Delay | 1–11ns - ensures sub-10ns worst-case timing margin for 50MHz bus cycles. |
| Output Drive | −15mA (IOH), 24mA (IOL) - directly drives up to 20 standard TTL loads per pin. |
| Input Thresholds | VIL = 0.8V, VIH = 2.0V - compatible with standard TTL logic levels and noise margins. |
| Operating Temp | 0°C to +70°C - qualified for commercial-grade embedded systems and industrial controllers. |
| 3-State Enable Time | tPZH ≤ 21ns, tPZL ≤ 24ns - supports fast bus turnaround in shared-memory architectures. |
Pinout & Package
DM74ALS640AN uses a 20-lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" wide, with through-hole mounting and standard 0.1" pin pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G) | Output Enable | Active-low global enable; HIGH isolates both A and B busses (3-state). |
| 2 (DIR) | Direction Control | LOW = B-to-A data flow; HIGH = A-to-B data flow (inverting transceiver). |
| 3–10 (A0–A7) | Input/Output Port A | Inverting bidirectional data lines; driven by B when DIR=LOW, drive B when DIR=HIGH. |
| 11 (GND) | Ground | Reference return for all signals and power dissipation path. |
| 12–19 (B0–B7) | Input/Output Port B | Inverting bidirectional data lines; driven by A when DIR=HIGH, drive A when DIR=LOW. |
| 20 (VCC) | Supply Voltage | +5V DC power input; decoupling required within 0.5" of pin for noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Inverting Transceiver Logic | Each data bit inverted on pass-through-enables direct connection to non-inverting receivers without external inverters. |
| PNP Input Structure | Reduces input loading to ≤20µA (IIH) and ≤−100µA (IIL), minimizing bus capacitance impact. |
| Guaranteed Switching | Specified over full temperature (0°C to +70°C) and VCC (4.5–5.5V) range-no derating needed in design. |
| 50pF Load Timing | Propagation and enable/disable delays validated at 50pF-matches typical PCB trace + TTL input capacitance. |
| Oxide-Isolated Schottky Process | Enables high-speed performance with low power consumption (ICC ≤ 55mA max under active drive). |
Applications
| Industrial Backplane Interconnect | Legacy CPU Bus Extension |
|---|---|
Use Scenario: Connecting multiple 8-bit peripheral modules to a central controller bus in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: Bidirectional inverting transceiver managing data flow between isolated I/O slots and main CPU bus. Use Value: Enables hot-swap isolation via G control and eliminates need for discrete inverters in address/data paths. |
Use Scenario: Extending Z80 or 8085 processor data/address bus to external memory banks in retro-computing systems. IC Role / Device Role / Timing Role: Level-shifting and direction-controlled bus repeater supporting asynchronous read/write handshaking. Use Value: Meets strict 11ns tPHL requirement for 4MHz CPU clock domains with no added setup/hold penalty. |
| TTL-Compatible Test Equipment | Automated Test Fixture Interface |
Use Scenario: Signal routing between DUT interface board and pattern generator/analyzer in benchtop ATE systems. IC Role / Device Role / Timing Role: Isolating and inverting test vectors during stimulus/response capture phases. Use Value: 3-state disable (G = HIGH) prevents bus contention during test mode transitions. |
Use Scenario: Interfacing microcontroller-based fixture controllers to legacy 8-bit sensor/actuator modules. IC Role / Device Role / Timing Role: Direction-flexible data bridge synchronizing command and status transfers. Use Value: DIR-controlled flow allows single device to handle both command-out and status-in on shared wiring. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS640N | Identical pinout, timing, and DC specs; manufactured by Texas Instruments with same ALS process. | No functional deviation-direct drop-in replacement in all legacy designs using DM74ALS640AN. | Select SN74ALS640N when TI-sourced ALS logic is preferred for supply chain diversification. |
| 74F640PC | Faster propagation (tPLH ≤ 6ns), higher ICC (≤75mA), non-inverting logic-requires signal polarity adjustment. | Not pin-compatible; requires PCB redesign and logic inversion in firmware/hardware for A/B data paths. | Choose 74F640PC only when sub-7ns timing is mandatory and system-level inversion can be accommodated. |
Compared with SN74ALS640N (identical function and pinout) and 74F640PC (faster but non-inverting and higher power), the DM74ALS640AN provides verified legacy compatibility, predictable 5V TTL loading, and minimal layout impact in maintenance and repair contexts.
Availability
DM74ALS640AN is available at Aetrix Electronics and suitable for industrial backplane interconnect, legacy CPU bus extension, and automated test fixture interface requiring stable component supply across long-lifecycle programs.
Supply support for DM74ALS640AN 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
Fairchild Semiconductor was a leading designer of analog and mixed-signal ICs, acquired by ON Semiconductor in 2016; its legacy TTL and ALS logic families remain widely supported.
The DM74ALS640AN belongs to Fairchild's advanced low-power Schottky (ALS) logic family, engineered for high-speed, low-noise bidirectional bus communication in commercial and industrial control systems.
FAQ
What logic family does the DM74ALS640AN belong to?
The DM74ALS640AN belongs to the Advanced Low-Power Schottky (ALS) TTL logic family. It uses oxide-isolated ion-implanted Schottky technology to achieve faster switching than standard LS TTL while maintaining compatibility with 5V TTL voltage levels. The DM74ALS640AN exhibits typical propagation delays of 1–11ns and operates across the full commercial temperature range (0°C to +70°C).
Does the DM74ALS640AN invert data during transmission?
Yes, the DM74ALS640AN is explicitly an inverting octal bus transceiver. Each data bit passing from A to B or B to A undergoes logical inversion-so a HIGH on A0 appears as LOW on B0, and vice versa. This behavior is inherent to the device's internal gate structure and is documented in the logic diagram and function table of the DM74ALS640AN datasheet.
What are the absolute maximum ratings for DM74ALS640AN?
The DM74ALS640AN has an absolute maximum supply voltage of 7V, input voltage limit of 7V on control pins and 5.5V on I/O ports, and operating free-air temperature range of 0°C to +70°C. Storage temperature spans −65°C to +150°C. Exceeding these limits may cause permanent damage; the DM74ALS640AN must be operated within recommended conditions (VCC = 4.5–5.5V, TA = 0–70°C) for guaranteed functionality.
Can DM74ALS640AN drive standard TTL loads directly?
Yes, the DM74ALS640AN can drive up to 20 standard TTL unit loads per output. Its IOL rating of 24mA and IOH rating of −15mA meet or exceed the current requirements of legacy TTL inputs (IIL = −1.6mA, IIH = 40µA). The DM74ALS640AN's PNP input design further reduces loading on upstream drivers, making it suitable for fan-out-critical bus topologies.
Is DM74ALS640AN pin-compatible with other octal transceivers?
The DM74ALS640AN is pin-compatible with SN74ALS640N and shares identical pinout, electrical specs, and timing. However, it is not pin-compatible with non-inverting variants like 74ALS245 or F-series 74F640-those differ in DIR/G assignment and logic polarity. Always verify pin functions using the DM74ALS640AN connection diagram before substitution.
DM74ALS640AN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74ALS
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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:
- Through Hole
- Supplier Device Package:
- 20-PDIP
DM74ALS640AN FAQ
1.How can I place an order for DM74ALS640AN through Aetrix?
Please submit a Request for Quotation (RFQ) for DM74ALS640AN 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 DM74ALS640AN reliable?
The price and inventory of DM74ALS640AN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DM74ALS640AN is usually 5 days.
3.What payment methods are accepted for DM74ALS640AN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DM74ALS640AN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DM74ALS640AN?
DM74ALS640AN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DM74ALS640AN 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 DM74ALS640AN?
For technical support, including DM74ALS640AN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DM74ALS640AN requirements.
6.How does Aetrix verify that DM74ALS640AN is sourced from the original manufacturer or authorized distributors?
All DM74ALS640AN 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 DM74ALS640AN meets industry standards.
7.What is the process for return or replacement of DM74ALS640AN?
All DM74ALS640AN units undergo pre-shipment inspection (PSI). If there is an issue with DM74ALS640AN, 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 DM74ALS640AN part is unused and in its original packaging.
Return procedure for DM74ALS640AN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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