My Inquiry
My Account
Texas Instruments SN74HCT240DW
- Part No.:
- SN74HCT240DW
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74HCT240DW.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,888
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SN74HCT240DW from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for memory address and bus driving in industrial control and embedded systems. It operates at 4.5–5.5 V, delivers ±6 mA output drive, exhibits 12 ns typical propagation delay, and supports TTL-compatible inputs. Its dual 4-bit structure with independent OE pins enables selective bus isolation in multi-drop data paths.
For engineers reviewing the SN74HCT240DW datasheet, SN74HCT240DW pinout, SN74HCT240DW application, or SN74HCT240DW equivalent, this page provides verified functional identity, SOIC-20 package mapping, confirmed 3-state inversion behavior, thermal resistance (RθJA = 109.1°C/W), and validated alternatives for bus interface redesigns requiring high-current drive and logic-level compatibility.
Technical Context
The SN74HCT240DW implements two independent 4-bit inverting buffers, each controlled by a dedicated output-enable (OE) input. When OE is low, inverted data passes from A inputs to Y outputs; when OE is high, all eight outputs enter high-impedance state-enabling bidirectional bus sharing without contention.
Its HCT logic family ensures CMOS power efficiency with TTL voltage-level compatibility: VIH = 2.0 V min, VIL = 0.8 V max at VCC = 4.5–5.5 V. Input leakage remains ≤1 μA, and ICC stays ≤80 μA under static conditions, supporting low-power system standby modes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures stable operation across standard 5 V rail tolerances and brown-out margins. |
| Propagation Delay (tpd) | 12 ns typical at 5.5 V, CL = 50 pF - Enables reliable timing in 33 MHz bus cycles with setup/hold margin. |
| Output Drive | ±6 mA at 5 V - Sufficient to drive 15 LSTTL loads directly, eliminating need for external fanout buffers. |
| Input Compatibility | TTL-voltage compatible (VIH ≥ 2.0 V, VIL ≤ 0.8 V) - Interoperates seamlessly with legacy 74LS and microcontroller GPIOs. |
| Quiescent Current (ICC) | 80 μA max - Supports low-static-power designs in always-on industrial controllers and sensor nodes. |
| 3-State Enable Timing (ten/tdis) | 19–40 ns (5.5 V, CL = 50 pF) - Guarantees clean bus release before next driver activation, preventing glitches. |
| Operating Temperature | –40°C to +85°C - Qualified for extended-temperature industrial environments including motor drives and PLC I/O modules. |
Pinout & Package
SN74HCT240DW uses a 20-pin SOIC (DW) package measuring 12.80 mm × 10.3 mm (body: 12.80 mm × 7.50 mm), with gull-wing leads and standard JEDEC MO-152 outline. Pin 1 index is marked by a beveled corner or dot.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1OE, 2OE | Active-low output enable controls for Group 1 (pins 2–9) and Group 2 (pins 11–18); independent gating prevents bus contention. |
| 2, 4, 6, 8, 11, 13, 15, 17 | 1A1–1A4, 2A1–2A4 | Inverting input terminals; logic low → high output, logic high → low output; TTL-compatible thresholds ensure robust noise immunity. |
| 3, 5, 7, 9, 12, 14, 16, 18 | 1Y1–1Y4, 2Y1–2Y4 | Inverting 3-state outputs; high-impedance when respective OE is high - essential for shared data/address bus arbitration. |
| 10 | GND | Ground reference for all logic and output stages; requires low-inductance connection to minimize switching noise coupling. |
| 20 | VCC | Positive supply (4.5–5.5 V); must be decoupled with 0.1 μF ceramic capacitor placed within 5 mm of pin per TI layout guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| Inverting 3-state buffering | Enables bidirectional bus control with deterministic signal polarity and contention-free release via separate OE pins. |
| TTL-compatible input thresholds | VIH = 2.0 V min / VIL = 0.8 V max ensures interoperability with 74LS, microcontrollers, and FPGA I/O banks without level shifters. |
| High-output current drive | ±6 mA per output supports direct interfacing to 15 LSTTL loads, reducing component count in address/data latching circuits. |
| Low quiescent power | 80 μA max ICC allows integration into power-sensitive applications like battery-backed real-time clocks and remote I/O modules. |
| Industrial temperature range | –40°C to +85°C operation meets requirements for factory automation, HVAC controllers, and transportation electronics. |
Applications
| Memory Address Buffering | Microcontroller Bus Expansion |
|---|---|
|
Use Scenario: Driving 16-bit address lines from an 8-bit MCU with external RAM/ROM. IC Role / Device Role / Timing Role: Inverting 3-state buffer isolating MCU address bus from memory chip inputs during wait states. Use Value: Prevents bus contention during memory access arbitration while maintaining TTL-compatible signal integrity at 12 ns propagation delay. |
Use Scenario: Expanding GPIO count for peripheral control in an industrial PLC baseboard. IC Role / Device Role / Timing Role: Octal buffer translating MCU GPIO logic levels to higher-current signals for relay drivers and LED indicators. Use Value: Delivers ±6 mA per channel to directly drive optocouplers and discrete transistors without external amplification. |
| Legacy System Bus Interface | Test Equipment Signal Conditioning |
|
Use Scenario: Interfacing modern FPGA-based logic analyzers to vintage 74LS-based computer backplanes. IC Role / Device Role / Timing Role: Level-shifting and fanout buffer matching LS-TTL voltage thresholds and loading requirements. Use Value: TTL-compatible inputs accept LS logic highs (2.4 V) and lows (0.4 V), while 3-state outputs prevent backfeeding into legacy bus segments. |
Use Scenario: Isolating DUT signals from test fixture wiring in automated board-level testers. IC Role / Device Role / Timing Role: Controlled-enable buffer inserting known propagation delay and impedance-matched drive into signal paths. Use Value: 12 ns tpd and 50 pF load capability provide predictable timing windows for jitter-sensitive parametric measurements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT240N | Same logic function and electrical specs, but in PDIP-20 package (24.33 mm × 9.4 mm); no moisture sensitivity level rating. | Better suited for prototyping, through-hole assembly, or legacy PCBs with DIP footprints; lacks SOIC's thermal performance (RθJA = 84.6°C/W vs. 109.1°C/W). | Select SN74HCT240N only when manual soldering or socket-based testing is required; not recommended for high-density reflow production. |
| SN74LV240APWR | LV-family variant: 2.0–5.5 V supply, lower drive (±8 mA), faster tpd (7.5 ns typ), but non-TTL-compatible inputs (VIH = 70% VCC). | Applicable in mixed-voltage systems (e.g., 3.3 V MCU + 5 V peripherals), but requires level validation at interface points due to ratio-based input thresholds. | Choose SN74LV240APWR only when operating below 4.5 V or needing sub-10 ns timing; verify VIH/VIL against source logic family to avoid misreads. |
Compared with SN74HCT240N and SN74LV240APWR, the SN74HCT240DW uniquely balances TTL compatibility, SOIC manufacturability, and industrial temperature support - making it optimal for volume-produced 5 V bus interfaces where legacy interoperability and reflow reliability are mandatory.
Availability
SN74HCT240DW is available at Aetrix Electronics and suitable for industrial control systems, legacy equipment upgrades, and embedded bus expansion requiring stable component supply and long-term sourcing continuity.
Supply support for SN74HCT240DW 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 specializing in analog, embedded processing, and logic solutions, with over 50 years of innovation in industrial and automotive electronics.
The SN74HCT240DW belongs to TI's 74HCT logic family, engineered for 5 V systems requiring TTL compatibility, low power, and robust 3-state bus driving - targeting memory subsystems, microcontroller peripherals, and industrial backplane interfaces.
FAQ
What is the logic function of the SN74HCT240DW?
The SN74HCT240DW contains two independent 4-bit inverting buffers, each with active-low 3-state output enable (OE). When OE is low, inputs A1–A4 pass inverted logic to outputs Y1–Y4; when OE is high, outputs go high-impedance. This architecture enables precise bus arbitration in memory and peripheral interfaces without signal contention.
Does the SN74HCT240DW support 3.3 V operation?
No, the SN74HCT240DW is specified only for 4.5 V to 5.5 V supply operation. Its TTL-compatible input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) and internal HCT circuitry require nominal 5 V biasing. For 3.3 V systems, consider SN74LV240APWR or SN74LVC240APWR, which are explicitly rated down to 1.65 V.
What is the thermal resistance of the SN74HCT240DW in SOIC package?
The SN74HCT240DW in DW (SOIC-20) package has a junction-to-ambient thermal resistance (RθJA) of 109.1°C/W under standard JEDEC test conditions. This value assumes a 1-inch² copper pad on a 1-layer board; actual board layout and copper area will affect real-world thermal performance.
Can unused inputs on the SN74HCT240DW be left floating?
No - all unused inputs on the SN74HCT240DW must be tied to VCC or GND to prevent undefined logic states and excessive current draw. TI specifies that floating CMOS inputs can cause increased ICC and erratic output behavior. Unused A inputs should connect to GND for logic-low default or VCC for logic-high, depending on desired idle output state.
Is the SN74HCT240DW pin-compatible with other 74HCT240 variants?
Yes - all 74HCT240 variants (e.g., SN74HCT240N, SN74HCT240DWR, SN74HCT240DGSR) share identical pinouts and logic functions across packages. The SN74HCT240DW pin configuration matches the standard 20-pin SOIC layout defined in TI's SCLS174H datasheet, enabling drop-in replacement between DW, N, DGS, NS, and PW variants where mechanical fit permits.
SN74HCT240DW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- 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:
- 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
SN74HCT240DW FAQ
1.How can I place an order for SN74HCT240DW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCT240DW 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 SN74HCT240DW reliable?
The price and inventory of SN74HCT240DW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCT240DW is usually 5 days.
3.What payment methods are accepted for SN74HCT240DW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HCT240DW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HCT240DW?
SN74HCT240DW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCT240DW 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 SN74HCT240DW?
For technical support, including SN74HCT240DW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCT240DW requirements.
6.How does Aetrix verify that SN74HCT240DW is sourced from the original manufacturer or authorized distributors?
All SN74HCT240DW 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 SN74HCT240DW meets industry standards.
7.What is the process for return or replacement of SN74HCT240DW?
All SN74HCT240DW units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCT240DW, 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 SN74HCT240DW part is unused and in its original packaging.
Return procedure for SN74HCT240DW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74HCT240DW Tags
-
SN74LVC1G17DBVR
Texas Instruments
-
SN74LVC1G07DCKR
Texas Instruments
-
SN74LVC1G17DCKR
Texas Instruments
-
SN74LVC1G07DBVR
Texas Instruments
-
SN74LVC1G125DCKR
Texas Instruments
-
SN74AHCT1G126DBVR
Texas Instruments
-
SN74LVC1G125DBVR
Texas Instruments
-
SN74AHCT1G125DBVR
Texas Instruments
-
SN74LVC2G17DBVR
Texas Instruments
-
SN74LVC2G07DCKR
Texas Instruments
-
SN74LVC1G34DCKR
Texas Instruments
-
SN74LVC2G17DCKR
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
