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Texas Instruments SN74AHCT240NSRE4
- Part No.:
- SN74AHCT240NSRE4
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHCT240NSRE4.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,624
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Product details
Overview
SN74AHCT240NSRE4 from Texas Instruments is an octal inverting buffer/driver with tri-state outputs, designed for bus-oriented receivers and transmitters in 5-V systems. It features TTL-compatible inputs (VIH = 2 V, VIL = 0.8 V), ±8 mA output drive, 9.5 ns max propagation delay at 5 V/50 pF, and operates from –40°C to 125°C. Used in network switches and television signal routing where level translation and bus isolation are required.
For engineers reviewing the SN74AHCT240NSRE4 datasheet, SN74AHCT240NSRE4 pinout, SN74AHCT240NSRE4 application, or SN74AHCT240NSRE4 equivalent, key selection criteria include its 20-pin SOP (NS) package, dual 4-bit inverting tri-state architecture, 5-V supply operation, input overvoltage tolerance up to 5.5 V, and compatibility with 3.3-V-to-5-V level translation in memory address and clock driver circuits.
Technical Context
The SN74AHCT240NSRE4 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 high, outputs enter high-impedance state. This architecture enables bidirectional bus control without external logic.
It uses advanced CMOS technology optimized for 5-V operation with TTL-voltage compatible inputs, allowing direct interfacing with legacy 3.3-V and 5-V logic families. Slow edge rates minimize output ringing and overshoot, critical in high-density PCB layouts with light capacitive loads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures stable operation across industrial 5-V rail tolerances. |
| Propagation Delay | 9.5 ns max (CL = 50 pF) - Supports ≤100-MHz bus timing in synchronous applications. |
| Output Drive | ±8 mA - Sufficient to drive standard TTL loads and short PCB traces without external buffering. |
| Input Compatibility | TTL-level (VIH = 2 V, VIL = 0.8 V) - Enables direct connection to 3.3-V microcontrollers and FPGAs without level shifters. |
| Operating Temperature | –40°C to +125°C - Qualified for automotive under-hood and industrial control environments. |
| Tri-State Enable Time | 13 ns max (tPZH/tPZL, CL = 50 pF) - Allows fast bus arbitration in multi-master systems. |
| ESD Rating | ±2000 V HBM - Meets IEC 61000-4-2 Level 2 for board-level ESD robustness. |
Pinout & Package
SN74AHCT240NSRE4 is packaged in a 20-pin SOP (Small Outline Package) with body dimensions of 12.6 mm × 5.3 mm and overall package size of 12.60 mm × 7.8 mm. The NS package is RoHS-compliant, tape-and-reel delivered (2000 pcs/reel), and rated MSL-1 (unlimited floor life).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 19OE | Active-Low Output Enable | Controls Group 1 (pins 2,4,6,8 → 18,16,14,12) and Group 2 (pins 11,13,15,17 → 9,5,3,1) independently; tie to VCC via pull-up for power-up high-Z safety. |
| 1A1–1A4, 2A1–2A4 | Inverting Input | Eight buffered inputs accepting TTL logic levels; inverted data appears on corresponding Y outputs when OE is asserted. |
| 1Y1–1Y4, 2Y1–2Y4 | Inverting Tri-State Output | Eight outputs providing inverted, high-drive signals; enter high-impedance state when respective OE is high. |
| VCC (Pin 20) | Power Supply | 5-V nominal supply; requires local 0.1 µF ceramic bypass capacitor placed adjacent to pin. |
| GND (Pin 10) | Ground Reference | Common return path for all internal logic and output drivers; must be low-inductance connection to system ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| 5-V CMOS with TTL input thresholds | Enables seamless integration with both legacy 5-V TTL and modern 3.3-V logic without external level-shifting circuitry. |
| Slow edge rate control | Reduces EMI and output ringing on unterminated transmission lines, improving signal integrity in compact layouts. |
| Input overvoltage tolerance | Accepts input voltages up to 5.5 V regardless of VCC, supporting hot-swap and mixed-voltage debug scenarios. |
| High-impedance state leakage | IOZ ≤ ±2.5 µA ensures minimal bus loading during disable, critical for shared-bus contention avoidance. |
| Latch-up immunity | Exceeds 250 mA per JESD17 - prevents destructive latch-up during transient overvoltage events on I/O pins. |
Applications
| Network Switches | Television Signal Routing |
|---|---|
Use Scenario: Isolating and buffering address/data buses between ASICs and DDR memory controllers in Layer 2/Layer 3 switching fabric. IC Role / Device Role / Timing Role: Octal inverting tri-state buffer providing direction-controlled, noise-immune bus interface with precise enable timing. Use Value: Prevents bus contention during state transitions while maintaining <10 ns propagation skew across all eight channels. |
Use Scenario: Translating and driving HDMI CEC or tuner control signals between 3.3-V SoC and 5-V analog front-end modules. IC Role / Device Role / Timing Role: Level-translating inverting driver enabling interoperability between mixed-voltage subsystems in broadcast-grade video equipment. Use Value: Eliminates need for discrete MOSFET translators, reducing BOM count and layout area while preserving signal edge monotonicity. |
| Industrial Power Infrastructure Monitoring | Health & Fitness Equipment Control |
Use Scenario: Buffering isolated sensor readouts (e.g., current shunt ADC outputs) to microcontroller GPIOs in AC/DC power supplies and UPS systems. IC Role / Device Role / Timing Role: High-noise-immunity inverting buffer isolating sensitive analog domain from noisy digital control logic. Use Value: TTL-compatible inputs reject common-mode noise on long sensor traces; ±8 mA drive ensures reliable sampling at MCU input thresholds. |
Use Scenario: Driving LED segment displays and tactile feedback indicators from low-power ARM Cortex-M0+ MCUs in portable fitness trackers. IC Role / Device Role / Timing Role: Inverting tri-state driver managing shared display bus while enabling dynamic power gating of unused segments. Use Value: Low ICC (40 µA max) extends battery life; 125°C rating supports operation inside thermally constrained wearable enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting tri-state buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AHCT240DWR | SOIC-20 (DW) package; 12.8 mm × 7.5 mm body; RθJA = 81.1°C/W vs. NS's 80.4°C/W. | Same electrical specs but larger footprint; preferred for manual assembly or legacy board compatibility. | Select DWR if existing PCB layout uses SOIC-20 land pattern or requires higher thermal mass for intermittent high-current bursts. |
| SN74LVC240APWR | 3.3-V only (1.65–3.6 V); lower drive (±24 mA); faster tPLH (5.1 ns typ); no TTL input compatibility. | Not suitable for 5-V or mixed-voltage systems; requires level shifting when interfacing with 5-V peripherals. | Choose LVC240APWR only in fully 3.3-V designs prioritizing speed and lower power over voltage flexibility. |
Compared with SN74AHCT240DWR and SN74LVC240APWR, SN74AHCT240NSRE4 uniquely balances 5-V operation, TTL input compatibility, and SOP packaging-making it optimal for cost-sensitive, mixed-voltage industrial and consumer electronics where board space and legacy interface support are critical.
Availability
SN74AHCT240NSRE4 is available at Aetrix Electronics and suitable for network switches, television signal routing, and industrial power infrastructure monitoring requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SN74AHCT240NSRE4 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 connectivity technologies, with over 50 years of innovation in logic IC design and manufacturing.
The SN74AHCT240NSRE4 belongs to TI's AHCT logic family, engineered for 5-V systems requiring TTL-compatible inputs, robust noise immunity, and reliable tri-state bus control in industrial and automotive applications.
FAQ
What is the maximum operating temperature for SN74AHCT240NSRE4?
The SN74AHCT240NSRE4 is rated for operation from –40°C to +125°C ambient temperature. This specification is validated per JEDEC JESD78 and applies to the NS package variant under recommended operating conditions (VCC = 4.5 V to 5.5 V). Thermal derating is not required within this range when mounted on standard FR-4 PCB with adequate copper pour.
Does SN74AHCT240NSRE4 support 3.3-V input logic levels?
Yes, SN74AHCT240NSRE4 accepts 3.3-V logic inputs reliably: its VIH threshold is specified at 2.0 V min, and VIL at 0.8 V max, making it fully compatible with 3.3-V CMOS and TTL outputs. Inputs tolerate up to 5.5 V regardless of VCC, enabling safe interfacing with overvoltage-prone sources.
Can SN74AHCT240NSRE4 be used as a non-inverting buffer?
No - SN74AHCT240NSRE4 is strictly an inverting octal buffer. Each A input drives a complementary Y output (e.g., A1 → Y1 with inversion). For non-inverting functionality, TI recommends SN74AHCT244NSRE4, which shares identical package, pinout, and electrical specs but provides true (non-inverted) buffering.
What is the recommended bypass capacitor for SN74AHCT240NSRE4?
A 0.1 µF X7R ceramic capacitor placed within 3 mm of the VCC (pin 20) and GND (pin 10) terminals is mandatory for stable operation. TI further recommends adding a 1.0 µF bulk capacitor nearby to suppress low-frequency supply ripple, especially in systems with multiple logic devices sharing the same 5-V rail.
Is SN74AHCT240NSRE4 pin-compatible with other AHCT240 variants?
Yes - all SN74AHCT240 variants (including DWR, PWR, DBR, and NSR) share identical 20-pin functional pinout and logic behavior. The NS package differs only in mechanical dimensions and thermal characteristics; no PCB redesign is needed when substituting among these variants, provided layout clearances accommodate the chosen body size.
SN74AHCT240NSRE4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Logic Type:
- Buffer, Inverting
- Number of Elements:
- 2
- Number of Bits per Element:
- 4
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 8mA, 8mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74AHCT240NSRE4 FAQ
1.How can I place an order for SN74AHCT240NSRE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT240NSRE4 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 SN74AHCT240NSRE4 reliable?
The price and inventory of SN74AHCT240NSRE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT240NSRE4 is usually 5 days.
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We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT240NSRE4 transactions.
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4.How is shipping managed for SN74AHCT240NSRE4?
SN74AHCT240NSRE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT240NSRE4 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 SN74AHCT240NSRE4?
For technical support, including SN74AHCT240NSRE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT240NSRE4 requirements.
6.How does Aetrix verify that SN74AHCT240NSRE4 is sourced from the original manufacturer or authorized distributors?
All SN74AHCT240NSRE4 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 SN74AHCT240NSRE4 meets industry standards.
7.What is the process for return or replacement of SN74AHCT240NSRE4?
All SN74AHCT240NSRE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT240NSRE4, 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 SN74AHCT240NSRE4 part is unused and in its original packaging.
Return procedure for SN74AHCT240NSRE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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