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onsemi DM74LS240WM
- Part No.:
- DM74LS240WM
- Manufacturer:
- onsemi
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
DM74LS240WM.pdf
- Description:
- IC BUFFER INVERT 5.25V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,346
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Product details
Overview
DM74LS240WM from Fairchild Semiconductor is an octal 3-STATE inverting buffer/line driver with PNP inputs, 0.4 V hysteresis per input, 24 mA sink and −15 mA source output drive, and 10.5 ns typical propagation delay (inverting), designed for memory address and clock bus driving in TTL-compatible systems.
For engineers reviewing the DM74LS240WM datasheet, pinout, applications, or equivalent options, key selection criteria include 3-STATE enable timing (18 ns typical), bus noise immunity via input hysteresis, high-fanout capability into 133 Ω terminated lines, and SOIC-20 package compatibility with JEDEC MS-013 footprint.
Technical Context
The DM74LS240WM implements eight independent inverting buffer channels, each with dual active-low 3-STATE enable inputs (G1̅ and G2̅) controlling all outputs simultaneously. Its PNP-based input structure reduces DC loading on shared bus lines while providing 0.4 V typical hysteresis to suppress noise-induced switching.
Each output delivers 24 mA sink current and −15 mA source current under VCC = 5 V, TA = 25 °C, supporting direct connection to terminated transmission lines down to 133 Ω. Output disable times are 18 ns (tPHZ) and 25 ns (tPLZ), enabling fast bus arbitration in bidirectional data paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.75 V to 5.25 V - ensures stable operation within standard TTL supply tolerance |
| Propagation Delay (tPLH) | 14 ns max at CL = 45 pF - enables reliable timing in 70 MHz-class address/clock distribution |
| IOL / IOH | 24 mA sink / −15 mA source - drives heavy capacitive loads and low-impedance terminated buses |
| Hysteresis (HYS) | 0.2–0.4 V - improves noise margin on shared data/address lines in noisy industrial environments |
| Enable Time (tPZH) | 23 ns max - supports rapid bus turnaround in multiplexed memory or I/O interfaces |
| Power Dissipation (enabled) | 130 mW typical (inverting) - compatible with dense PCB layouts without forced cooling |
| Operating Temperature | 0 °C to +70 °C - rated for commercial-grade embedded and computing applications |
Pinout & Package
DM74LS240WM is housed in a 20-lead Small Outline Integrated Circuit (SOIC) package per JEDEC MS-013, 0.300" wide, with standard 1.27 mm pitch and gull-wing leads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | Active-low Output Enable (G1̅, G2̅) | Both must be LOW to enable all eight inverting outputs; HIGH places outputs in high-impedance state |
| 2–9 | Inverting Data Inputs (1A–8A) | PNP-input logic signals; 0.4 V hysteresis improves noise rejection on shared buses |
| 11–18 | Inverting Outputs (1Y–8Y) | 3-STATE CMOS/TTL-compatible outputs; 24 mA sink capability drives 133 Ω terminated lines |
| 10 | GND | Ground reference for all logic and power functions |
| 20 | VCC | +5 V supply rail; decoupling capacitor required near pin for stable switching |
Key Features
| Feature | Design Value |
|---|---|
| Octal inverting 3-STATE buffers | Eight independent channels with common dual enable control for synchronized bus access |
| PNP input structure | Reduces DC loading on driven bus lines, preserving signal integrity in multi-drop configurations |
| 0.4 V typical input hysteresis | Rejects transient noise up to ±200 mV on address or control lines without external filtering |
| 18 ns typical enable/disable time | Enables fast bus sharing between CPU, DMA, and peripheral controllers in legacy systems |
| SOIC-20 JEDEC MS-013 footprint | Direct replacement for PDIP-20 in space-constrained designs without layout redesign |
Applications
| Memory Address Buffering | Clock Distribution |
|---|---|
Use Scenario: Driving 16-bit address bus from microprocessor to multiple memory ICs in 8080/Z80-based systems. IC Role / Device Role / Timing Role: Inverting 3-STATE buffer isolating CPU address outputs and enabling memory chip select arbitration. Use Value: 24 mA sink current and 10.5 ns propagation delay ensure setup/hold timing compliance across 4–8 memory devices. | Use Scenario: Distributing system clock to multiple synchronous peripherals with matched skew. IC Role / Device Role / Timing Role: Low-skew inverting line driver buffering and fanout expansion of master clock signal. Use Value: 0.4 V hysteresis prevents false triggering from clock edge noise; 133 Ω drive capability matches common PCB trace impedance. |
| Bus Transceiver Interface | Legacy I/O Expansion |
Use Scenario: Bidirectional data bus isolation between CPU and peripheral cards in ISA-style backplanes. IC Role / Device Role / Timing Role: 3-STATE-enabled inverting buffer acting as controlled direction gate for shared data lines. Use Value: 18 ns enable/disable time allows sub-50 ns bus turnaround, meeting early PC/industrial bus timing budgets. | Use Scenario: Expanding parallel I/O ports on 8-bit microcontrollers with limited drive strength. IC Role / Device Role / Timing Role: Level-shifting and current-boosting buffer for GPIO-connected displays, keypads, or relays. Use Value: −15 mA source and 24 mA sink support LED arrays and small solenoids without external drivers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting 3-STATE buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS240N | Dual active-low enables; identical electrical specs; PDIP-20 package only | No SOIC option; higher thermal resistance; requires through-hole assembly | Select when legacy through-hole manufacturing or socket-based prototyping is required |
| MC74LS240NG | Same logic function and timing; ON Semiconductor rebrand; SOIC-20 and PDIP-20 variants available | Identical pinout and DC/AC specs; minor packaging branding difference | Select when sourcing continuity post-Fairchild acquisition is prioritized |
Compared with SN74LS240N and MC74LS240NG, the DM74LS240WM offers identical functional behavior and timing but provides JEDEC MS-013 SOIC-20 packaging optimized for surface-mount production, reduced board area, and improved thermal performance over PDIP alternatives.
Availability
DM74LS240WM is available at Aetrix Electronics and suitable for memory address buffering, clock distribution, and bus-oriented transmitter/receiver applications requiring stable component supply and long-term industrial availability.
Supply support for DM74LS240WM 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 designer and manufacturer of analog and mixed-signal semiconductors, acquired by ON Semiconductor in 2016.
The DM74LS240WM belongs to the 74LS logic family, engineered for high-speed, low-power TTL-compatible digital interfacing in computing, instrumentation, and industrial control systems.
FAQ
What is the logic function of the DM74LS240WM?
The DM74LS240WM is an octal inverting 3-STATE buffer with dual active-low enable inputs (G1̅ and G2̅). Each of its eight channels accepts a logic input (1A–8A), inverts it, and drives the corresponding output (1Y–8Y) when both enables are LOW. When either enable is HIGH, all outputs enter high-impedance state. This function is confirmed in the device's Function Table and General Description sections of the Fairchild DS006411 datasheet.
Does the DM74LS240WM support noninverting operation?
No, the DM74LS240WM provides inverting logic only. The DM74LS241WM is the noninverting counterpart in the same family, sharing identical pinout, package, and timing specifications except for polarity. The DM74LS240WM's Function Table explicitly shows Y = A̅, confirming inversion; no internal configuration or external wiring enables noninverting mode.
What is the maximum load impedance the DM74LS240WM can drive reliably?
The DM74LS240WM is specified to drive terminated lines down to 133 Ω, as stated in the General Description. This capability derives from its 24 mA sink and −15 mA source output drive strength under VCC = 5 V and TA = 25 °C. Driving lower impedances risks exceeding absolute maximum ratings and is not characterized or guaranteed in the DS006411 datasheet.
Is the DM74LS240WM RoHS compliant?
The original DM74LS240WM, manufactured prior to Fairchild's RoHS transition, is not RoHS compliant. It contains lead in solder and die attach materials per JEDEC MS-013 SOIC construction of that era. For RoHS-compliant alternatives, consider ON Semiconductor's MC74LS240DR2G (SOIC-20, lead-free), which maintains pin and function compatibility with updated environmental compliance.
Can the DM74LS240WM operate at 3.3 V?
No, the DM74LS240WM is designed for 5 V nominal operation, with recommended VCC range of 4.75 V to 5.25 V. Its input thresholds (VIH = 2.0 V min, VIL = 0.8 V max) and output drive characteristics are specified only at VCC = 5 V. Operation at 3.3 V falls outside recommended conditions and results in undefined logic levels, degraded noise margins, and unreliable 3-STATE control.
DM74LS240WM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74LS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bag
- 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:
- 4.75V ~ 5.25V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
DM74LS240WM FAQ
1.How can I place an order for DM74LS240WM through Aetrix?
Please submit a Request for Quotation (RFQ) for DM74LS240WM 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 DM74LS240WM reliable?
The price and inventory of DM74LS240WM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DM74LS240WM is usually 5 days.
3.What payment methods are accepted for DM74LS240WM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DM74LS240WM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DM74LS240WM?
DM74LS240WM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DM74LS240WM 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 DM74LS240WM?
For technical support, including DM74LS240WM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DM74LS240WM requirements.
6.How does Aetrix verify that DM74LS240WM is sourced from the original manufacturer or authorized distributors?
All DM74LS240WM 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 DM74LS240WM meets industry standards.
7.What is the process for return or replacement of DM74LS240WM?
All DM74LS240WM units undergo pre-shipment inspection (PSI). If there is an issue with DM74LS240WM, 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 DM74LS240WM part is unused and in its original packaging.
Return procedure for DM74LS240WM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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