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Texas Instruments SN74HC240NE4
- Part No.:
- SN74HC240NE4
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74HC240NE4.pdf
- Description:
- 8-CH, 2-V TO 6-V INVERTERS WITH
- Quantity:
- Payment:
- Shipping:
Inventory:4,454
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Product details
Overview
SN74HC240NE4 from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for memory address and bus driving applications. It operates from 2V to 6V, delivers ±6mA output drive at 5V, features typical propagation delay of 9ns, and consumes ≤80µA ICC - enabling high-density, low-power bus interfacing in industrial control and embedded systems.
For engineers reviewing the SN74HC240NE4 datasheet, SN74HC240NE4 pinout, SN74HC240NE4 application, or SN74HC240NE4 equivalent, key selection criteria include its dual 4-bit inverting architecture, independent OE control per group, 3-state output behavior, and PDIP-20 package compatibility with legacy through-hole designs.
Technical Context
The SN74HC240NE4 implements two independent 4-bit inverting buffer/driver sections, each with dedicated output-enable (OE) inputs. 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 external logic.
Its CMOS HC-family design ensures TTL-compatible input thresholds, rail-to-rail output swing, and robust noise immunity across the full 2V–6V supply range. The device supports memory address latching, clock distribution, and peripheral interface buffering where signal inversion and bus contention avoidance are required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2V to 6V - enables interoperability with 3.3V and 5V logic domains without level shifters |
| Output Drive | ±6mA at 5V - sufficient to directly drive 15 LSTTL loads, eliminating need for external buffers |
| Propagation Delay | 9ns typical at VCC = 4.5V, CL = 50pF - supports high-speed address/data bus operation up to ~50MHz |
| Quiescent Current | ≤80µA max - enables use in low-power standby modes without significant current draw |
| Input Leakage | ≤1µA max - prevents unintended logic transitions on unterminated or high-impedance inputs |
| 3-State Enable Time | 25ns max (ten) at VCC = 4.5V - ensures fast bus release for time-critical arbitration protocols |
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade embedded and control applications |
Pinout & Package
SN74HC240NE4 is supplied in a 20-pin plastic dual in-line package (PDIP), with 0.300-inch body width, 0.100-inch lead pitch, and through-hole mounting compatibility. Pin 1 is located at the left end of the top row, identified by a notch or dot marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1OE, 2OE | Active-low enable inputs controlling Group 1 (pins 2–9) and Group 2 (pins 11–18) independently |
| 2, 4, 6, 8 11, 13, 15, 17 | 1A1–1A4, 2A1–2A4 | Inverting input terminals - logic high yields low output; logic low yields high output |
| 3, 5, 7, 9 12, 14, 16, 18 | 1Y1–1Y4, 2Y1–2Y4 | Inverting 3-state outputs - driven only when respective OE is low; otherwise high-Z |
| 10 | GND | Ground reference for all internal circuitry and output current return path |
| 20 | VCC | Positive supply rail - must be bypassed with 0.1µF ceramic capacitor near pin for stable switching |
Key Features
| Feature | Design Value |
|---|---|
| Inverting 3-state outputs | Enables bidirectional bus control with deterministic signal polarity and contention-free release |
| Dual independent OE inputs | Allows selective activation of either 4-bit group - simplifies partial bus access and reduces power during idle cycles |
| Wide 2V–6V supply range | Supports mixed-voltage system integration and brown-out tolerant operation down to 2V |
| Low ICC and IIL | Minimizes system-level quiescent current and prevents loading of upstream drivers or pull-up networks |
| TTL-compatible input thresholds | Ensures reliable interfacing with legacy 5V TTL and modern 3.3V CMOS without external biasing |
Applications
| Memory Address Buffering | Industrial Bus Interface |
|---|---|
Use Scenario: Driving address lines from microcontroller to multiple SRAM or EPROM devices on shared bus. IC Role / Device Role / Timing Role: Inverting 3-state buffer isolating CPU address outputs and enabling chip-select controlled memory access. Use Value: Prevents bus contention during memory read/write cycles while maintaining signal integrity over 15cm traces. | Use Scenario: Interfacing PLC I/O modules with backplane data buses operating at 10–20MHz. IC Role / Device Role / Timing Role: Level-shifting and bus-driving buffer for RS-485 transceiver control signals and status lines. Use Value: Delivers ±6mA drive into 50Ω terminated lines, ensuring clean edge transitions and noise margin >0.8V. |
| Legacy System Upgrade | Test Equipment Signal Conditioning |
Use Scenario: Replacing obsolete 74LS240 in aging instrumentation chassis requiring pin-compatible upgrade. IC Role / Device Role / Timing Role: Drop-in CMOS replacement providing identical pinout, function, and timing with lower power and wider voltage range. Use Value: Eliminates need for 5V-only supply rails and reduces board-level heat dissipation by >90% vs. LS family. | Use Scenario: Conditioning digital trigger and gate signals in automated test equipment with variable load capacitance. IC Role / Device Role / Timing Role: Controlled-impedance driver stage isolating FPGA outputs from reactive probe loads up to 100pF. Use Value: Maintains <9ns tpd variation across CL = 50–150pF, preserving sub-100ns timing margins in high-speed test sequences. |
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 | CMOS input with TTL-compatible thresholds; identical pinout and function but optimized for 5V-only operation | Better noise immunity in noisy 5V industrial environments; not suitable for 2V–3.3V mixed-supply systems | Select when system uses strict 5V logic and requires tighter VIH/VIL margins than HC family |
| 74AC240PC | Faster tpd (5.5ns typ), higher drive (±24mA), but higher ICC (40µA typical) and narrower 2V–6V range (2V–5.5V) | Preferred for high-speed data acquisition front-ends requiring minimal skew between channels | Select when propagation delay and output slew rate are critical, and power budget allows higher ICC |
Compared with SN74HCT240N and 74AC240PC, SN74HC240NE4 provides the broadest supply voltage flexibility (2V–6V), lowest quiescent current (≤80µA), and proven reliability in long-lifecycle industrial PCBs - making it optimal for cost-sensitive, multi-voltage, and legacy-compatible designs.
Availability
SN74HC240NE4 is available at Aetrix Electronics and suitable for industrial control panels, legacy test equipment upgrades, and embedded memory subsystems requiring stable component supply and long-term manufacturability.
Supply support for SN74HC240NE4 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 for industrial, automotive, and communications markets.
The SN74HC240NE4 belongs to TI's industry-standard 74HC logic family, engineered for high-density, low-power bus interfacing in memory, clock, and peripheral control applications where reliability and wide voltage operation are essential.
FAQ
What is the function of the OE pins on SN74HC240NE4?
The SN74HC240NE4 has two active-low output-enable pins: 1OE (pin 1) controls the first group of four inverting buffers (1A1–1A4 → 1Y1–1Y4), and 2OE (pin 19) controls the second group (2A1–2A4 → 2Y1–2Y4). When an OE pin is low, its corresponding Y outputs actively drive inverted logic levels; when high, those outputs enter high-impedance state - enabling independent bus segment control without external gating logic.
Can SN74HC240NE4 operate reliably at 3.3V supply?
Yes, SN74HC240NE4 is fully specified for operation from 2V to 6V, including 3.3V. At VCC = 3.3V, it maintains guaranteed VOH ≥ 3.15V and VOL ≤ 0.1V under 6mA load, with typical tpd of ~12ns (CL = 50pF). Its HC-family CMOS process ensures stable performance across this range without derating.
Is SN74HC240NE4 pin-compatible with older 74LS240 devices?
Yes, SN74HC240NE4 uses the same 20-pin PDIP footprint and identical pin configuration as 74LS240, including matching A/Y/OE/GND/VCC assignments. However, it is not electrically drop-in: SN74HC240NE4 draws significantly less current, has higher output drive, and exhibits faster switching - requiring verification of timing margins and bus loading in legacy designs.
What is the maximum capacitive load SN74HC240NE4 can drive while maintaining timing specs?
SN74HC240NE4 is characterized for CL = 50pF and CL = 150pF. At VCC = 4.5V, tpd increases from 25ns (50pF) to 38ns (150pF); transition time (tt) rises from 15ns to 53ns. For designs requiring <30ns tpd, total load (including trace, connector, and input capacitance) should be kept ≤100pF to maintain timing margin.
Does SN74HC240NE4 require external pull-up resistors on its OE inputs?
No - SN74HC240NE4 OE inputs are CMOS-compatible with rail-to-rail voltage thresholds. When driven directly from logic outputs (e.g., MCU GPIO), no pull-ups are needed. If left unconnected, OE floats high (disabling outputs), but TI recommends tying unused OE pins to VCC or GND to prevent noise-induced switching and ensure deterministic behavior.
SN74HC240NE4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Logic Type:
- Buffer, Inverting
- Number of Elements:
- 2
- Number of Bits per Element:
- 4
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 7.8mA, 7.8mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74HC240NE4 FAQ
1.How can I place an order for SN74HC240NE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC240NE4 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 SN74HC240NE4 reliable?
The price and inventory of SN74HC240NE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC240NE4 is usually 5 days.
3.What payment methods are accepted for SN74HC240NE4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC240NE4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC240NE4?
SN74HC240NE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC240NE4 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 SN74HC240NE4?
For technical support, including SN74HC240NE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC240NE4 requirements.
6.How does Aetrix verify that SN74HC240NE4 is sourced from the original manufacturer or authorized distributors?
All SN74HC240NE4 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 SN74HC240NE4 meets industry standards.
7.What is the process for return or replacement of SN74HC240NE4?
All SN74HC240NE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC240NE4, 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 SN74HC240NE4 part is unused and in its original packaging.
Return procedure for SN74HC240NE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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