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onsemi DM74ALS240AWMX
- Part No.:
- DM74ALS240AWMX
- Manufacturer:
- onsemi
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
DM74ALS240AWMX.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,994
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Product details
Overview
DM74ALS240AWMX from Fairchild Semiconductor is an octal 3-STATE bus driver IC designed for bidirectional data bus interfacing in memory and microprocessor systems. It features two independent 4-bit groups with active-low enable control, 24mA low-level output drive, 5V supply operation, and guaranteed switching performance into 500Ω/50pF loads across 0°C to +70°C.
For engineers reviewing the DM74ALS240AWMX datasheet, pinout, applications, or equivalent options, this device serves as a legacy-compatible, low-power Schottky TTL buffer for industrial control backplanes, legacy instrumentation data buses, and embedded system address/data latching interfaces where controlled bus contention avoidance is required.
Technical Context
The DM74ALS240AWMX implements dual-group 3-STATE gating with symmetric active-low enables (1G, 2G), enabling independent control of two 4-bit output banks. Its PNP input structure reduces input loading, and internal power-up/power-down protection holds outputs in high-impedance state during VCC ramp transitions.
It operates strictly within 4.5V–5.5V VCC, delivers –15mA high-level and 24mA low-level output current, and guarantees propagation delays of 2–9ns (tPLH/tPHL) and enable/disable times of 2–18ns under 50pF/500Ω load conditions across full temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5V to 5.5V - Ensures compatibility with standard 5V TTL logic rails and noise margin stability |
| IOL / IOH | 24mA / –15mA - Supports direct driving of multiple LS-TTL inputs without external buffers |
| tPLH / tPHL | 2ns to 9ns - Enables reliable operation in sub-10ns timing-critical bus cycles |
| 3-STATE Enable/Disable | tPZH ≤13ns, tPLZ ≤12ns - Minimizes bus float duration during direction switching |
| Input Loading | IIL = –0.1mA, IIH = 20µA - Reduces fanout burden on upstream drivers |
| Operating Temp | 0°C to +70°C - Qualified for commercial-grade industrial control and instrumentation environments |
Pinout & Package
DM74ALS240AWMX is housed in a 20-lead SOIC package (JEDEC MS-013, 0.300" wide, Package Code M20B), with 1.27mm pitch and gull-wing leads suitable for surface-mount reflow assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | Group 1 & 2 Output Enable (Active Low) | Simultaneously places Y1–Y4 or Y5–Y8 into high-impedance when HIGH |
| 2–5, 13–16 | Data Inputs (A1–A4, A5–A8) | CMOS/TTL-compatible inputs accepting 0.8V/2.0V thresholds |
| 6–9, 11–14 | 3-STATE Outputs (Y1–Y4, Y5–Y8) | Drive capability up to 24mA sink; clamped to –1.5V for ESD protection |
| 10 | GND | Signal and power reference plane for noise-sensitive bus interface |
| 20 | VCC | 5V supply pin with 10mA typical ICC (3-STATE mode) for low static power |
Key Features
| Feature | Design Value |
|---|---|
| Advanced ALS process | Ion-implanted Schottky TTL delivering 30% lower power vs. LS while maintaining speed |
| Power-ramp 3-STATE hold | Internal circuitry forces outputs to high-Z during VCC rise/fall, eliminating bus glitches |
| PNP input structure | Reduces input current loading to –0.1mA (LOW) and 20µA (HIGH), easing driver requirements |
| Guaranteed load switching | Specified performance into 500Ω series + 50pF parallel load - matches real-world PCB trace + receiver capacitance |
Applications
| Industrial Backplane Bus Interface | Legacy Microprocessor Address Latching |
|---|---|
Use Scenario: Interfacing multiple peripheral cards to a shared 8-bit data bus in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: Bidirectional bus driver providing isolated, enable-controlled data path between CPU and I/O modules. Use Value: Dual 4-bit enables allow staggered arbitration; 24mA drive ensures signal integrity across 15cm backplane traces. | Use Scenario: Latching 8-bit address segments from Z80 or 8085 CPUs to decode memory-mapped peripherals. IC Role / Device Role / Timing Role: Unidirectional address buffer with 3-STATE control synchronized to ALE/IO/M signals. Use Value: Sub-10ns propagation delay meets tight setup/hold windows; low input loading avoids clock skew on shared address lines. |
| Test Equipment Signal Routing | Embedded Instrumentation Data Multiplexing |
Use Scenario: Switching analog-to-digital converter outputs onto a common diagnostic bus in automated test systems. IC Role / Device Role / Timing Role: Digital multiplexer substitute using enable-controlled 3-STATE outputs to prevent bus contention. Use Value: Guaranteed 0.35V VOL at 24mA ensures clean logic LOW detection by downstream comparators or FPGA inputs. | Use Scenario: Sharing sensor data streams (e.g., thermocouple digitizers, pressure transducers) across a single RS-485 controller interface. IC Role / Device Role / Timing Role: Data concentrator buffer isolating individual sensor modules from shared communication bus. Use Value: Power-ramp 3-STATE hold prevents false readings during cold-start sequencing of modular sensor nodes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal 3-STATE bus driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS240N | Dual-in-line (PDIP) package; identical electrical specs and pinout | Suitable for through-hole prototyping or legacy repair; lacks SOIC thermal performance (θJA = 60.5°C/W vs. 79.8°C/W) | Select when board rework or hand-soldering is required; same logic behavior and timing |
| MC74ALS240N | Motorola second-source version; identical function, timing, and DC specs per datasheet Rev. 3 | Same industrial temperature range and bus-driving capability; minor packaging marking variance | Use for supply chain diversification where Fairchild sourcing is constrained |
Compared with SN74ALS240N and MC74ALS240N, the DM74ALS240AWMX offers superior thermal resistance in SOIC format for higher-density layouts, while retaining full functional and timing equivalence - making it optimal for new SMT-based industrial control designs requiring long-term component availability.
Availability
DM74ALS240AWMX is available at Aetrix Electronics and suitable for industrial backplane bus interfaces, legacy microprocessor address latching, and embedded instrumentation data multiplexing requiring stable component supply and long-lifecycle support.
Supply support for DM74ALS240AWMX 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 U.S.-based semiconductor company specializing in analog and mixed-signal ICs, acquired by ON Semiconductor in 2016; its legacy logic portfolio remains widely deployed in industrial systems.
The DM74ALS240AWMX belongs to the Advanced Low-Power Schottky (ALS) logic family, engineered for high-speed, low-power bus interfacing in memory expansion, microprocessor support, and industrial control subsystems.
FAQ
What is the operating voltage range for DM74ALS240AWMX?
The DM74ALS240AWMX operates over a supply voltage range of 4.5V to 5.5V, with recommended nominal VCC at 5.0V. This range ensures compatibility with standard TTL logic families and provides sufficient noise margin for industrial environments. Operation outside this range may cause undefined behavior or damage, as absolute maximum VCC is 7V but not functional.
Does DM74ALS240AWMX support hot insertion or live bus swapping?
The DM74ALS240AWMX does not include explicit hot-swap protection circuitry. However, its built-in power-ramp 3-STATE hold feature maintains outputs in high-impedance during VCC transitions, reducing glitch risk during controlled power sequencing. For true hot-plug applications, external current-limiting and voltage-ramping circuits are required alongside DM74ALS240AWMX.
How does the DM74ALS240AWMX differ from the DM74LS240 in practical use?
The DM74ALS240AWMX delivers faster switching (2–9ns vs. 15–25ns typical for LS), lower power consumption (14–25mA ICC in 3-STATE vs. ~35mA for LS), and reduced input loading due to PNP input design. These differences allow tighter timing margins and lower system power in bus-intensive designs without changing pinout or logic function.
Can DM74ALS240AWMX drive standard LS-TTL loads directly?
Yes, DM74ALS240AWMX can directly drive up to 20 LS-TTL inputs per output, based on its 24mA sink capability and –15mA source rating. Its VOL of 0.35V (max) at 24mA and VOH of ≥2.4V (min) at –0.4mA meet LS-TTL input threshold requirements, eliminating need for additional level-shifting or buffering stages in most legacy system integrations.
Is the DM74ALS240AWMX RoHS compliant?
The DM74ALS240AWMX was manufactured prior to RoHS enforcement and is not RoHS compliant; it contains lead in solder finish and die attach materials. For new designs requiring RoHS compliance, consider modern alternatives such as 74LVC240 or contact Aetrix Electronics for verified drop-in replacements with updated environmental certification.
DM74ALS240AWMX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Logic Type:
- Buffer, Inverting
- Number of Elements:
- 2
- Number of Bits per Element:
- 4
- 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
DM74ALS240AWMX FAQ
1.How can I place an order for DM74ALS240AWMX through Aetrix?
Please submit a Request for Quotation (RFQ) for DM74ALS240AWMX 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 DM74ALS240AWMX reliable?
The price and inventory of DM74ALS240AWMX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DM74ALS240AWMX is usually 5 days.
3.What payment methods are accepted for DM74ALS240AWMX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DM74ALS240AWMX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DM74ALS240AWMX?
DM74ALS240AWMX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DM74ALS240AWMX 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 DM74ALS240AWMX?
For technical support, including DM74ALS240AWMX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DM74ALS240AWMX requirements.
6.How does Aetrix verify that DM74ALS240AWMX is sourced from the original manufacturer or authorized distributors?
All DM74ALS240AWMX 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 DM74ALS240AWMX meets industry standards.
7.What is the process for return or replacement of DM74ALS240AWMX?
All DM74ALS240AWMX units undergo pre-shipment inspection (PSI). If there is an issue with DM74ALS240AWMX, 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 DM74ALS240AWMX part is unused and in its original packaging.
Return procedure for DM74ALS240AWMX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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