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Texas Instruments SN74HC240ANSR
- Part No.:
- SN74HC240ANSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74HC240ANSR.pdf
- Description:
- IC BUFFER INVERT 6V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,941
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Product details
Overview
SN74HC240ANSR 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, exhibits 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 SN74HC240ANSR datasheet, SN74HC240ANSR pinout, SN74HC240ANSR application, or SN74HC240ANSR equivalent, this page provides verified functional modes, package-specific pin mapping (PDIP-20), real-world timing behavior under 50pF load, and validated alternatives for bus buffering in legacy and new-design contexts.
Technical Context
The SN74HC240ANSR implements two independent 4-bit inverting buffer sections, each controlled by a dedicated output-enable (OE) input. When OE is low, inverted logic passes from A inputs to Y outputs; when OE is high, all eight outputs enter high-impedance state - enabling bidirectional bus arbitration without external logic.
Its CMOS HCMOS architecture ensures rail-to-rail output swing, low input current (≤1µA), and compatibility with LSTTL loads (up to 15). The device supports wide VCC range (2–6V), making it suitable for mixed-voltage system interfaces where level translation is not required but robust noise immunity and predictable switching thresholds are critical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2V to 6V - enables direct interface with 3.3V and 5V logic domains without level shifters |
| Output Drive | ±6mA at 5V - sufficient to sink/source 15 LSTTL loads, supporting legacy TTL bus termination |
| Propagation Delay | 9ns typical (VCC = 4.5V, CL = 50pF) - ensures sub-10ns timing margin for 50MHz bus cycles |
| ICC (max) | 80µA - enables low-static-power operation in battery-backed or energy-constrained systems |
| Input Current | ≤1µA max - eliminates need for pull-up/pull-down resistors on unused inputs in high-impedance states |
| 3-State Enable Time | 25ns max (VCC = 4.5V, CL = 50pF) - guarantees fast bus release during multi-master arbitration |
Pinout & Package
SN74HC240ANSR is supplied in a 20-pin plastic dual in-line package (PDIP), with 0.300-inch body width and through-hole mounting. 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 |
|---|---|---|
| 1OE | Active-low enable for first 4-bit section | Drives Y1–Y4 high-impedance when high; enables inverted A1–A4 → Y1–Y4 when low |
| 1A1–1A4 | Inputs for first inverting buffer group | Accept logic signals; outputs Y1–Y4 reflect logical inversion when 1OE is active |
| 1Y1–1Y4 | Inverted outputs for first group | Drive bus lines or memory address registers; high-Z when 1OE is inactive |
| 2OE | Active-low enable for second 4-bit section | Independent control of Y5–Y8; allows asymmetric bus partitioning |
| 2A1–2A4 | Inputs for second inverting buffer group | Electrically isolated from first group; supports separate data paths |
| 2Y1–2Y4 | Inverted outputs for second group | Match timing and drive strength of first group; share same VCC/GND rails |
| VCC (Pin 20) | Positive supply | Must be bypassed with 0.1µF ceramic capacitor placed within 5mm of pin for stable switching |
| GND (Pin 10) | Ground reference | Common return for all I/O and supply currents; connects to system ground plane |
Key Features
| Feature | Design Value |
|---|---|
| Inverting 3-state buffers | Two independent 4-bit sections with separate OE pins enable selective bus isolation without external gating logic |
| Wide VCC range (2–6V) | Supports direct integration into both 3.3V microcontroller buses and 5V legacy peripheral interfaces |
| High-output current (±6mA @ 5V) | Drives standard LSTTL loads without external transistors, reducing component count in address/data latching circuits |
| Low ICC (≤80µA) | Minimizes quiescent power in always-on bus controllers, extending runtime in standby-mode industrial gateways |
| Fast tpd (9ns typ) | Meets timing budgets for 50MHz synchronous bus protocols such as ISA-compatible memory expansion |
Applications
| Memory Address Buffering | Industrial Bus Transceiver |
|---|---|
|
Use Scenario: Driving 20-bit address bus between microcontroller and SRAM/ROM in programmable logic controllers. IC Role / Device Role / Timing Role: Inverts and buffers address lines while enabling/disabling bus access via OE control during DMA cycles. Use Value: Eliminates timing skew across address bits and prevents bus contention during peripheral handshaking. |
Use Scenario: Isolating CAN controller address/data lines from shared backplane in modular automation racks. IC Role / Device Role / Timing Role: Provides direction-controlled signal conditioning between microcontroller GPIO and bus transceivers. Use Value: Enables hot-swap capability by placing unused bus segments in high-Z state during module insertion/removal. |
| Legacy Peripheral Interface | Test Equipment Signal Conditioning |
|
Use Scenario: Interfacing FPGA-based test pattern generator with vintage 8086-based instrumentation hardware. IC Role / Device Role / Timing Role: Converts modern 3.3V logic levels to 5V-compatible inverted signals for address latch enable and chip select decoding. Use Value: Maintains setup/hold timing integrity across voltage domain boundaries without active level translators. |
Use Scenario: Driving multiple parallel DUT (device-under-test) inputs from a single pattern generator channel in ATE systems. IC Role / Device Role / Timing Role: Splits and inverts one stimulus signal to four synchronized outputs with matched propagation delay. Use Value: Ensures deterministic phase alignment across DUT channels, critical for parametric timing 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 | TTL-compatible input thresholds (VIH = 2V min), otherwise identical pinout and function | Better suited for mixed 5V TTL/CMOS systems where input noise margins must match legacy TTL logic families | Select when interfacing with older 74LS or 74ALS devices requiring guaranteed VIH/VIL thresholds |
| 74AC240PC | Faster tpd (5.5ns typ), higher ICC (40mA max), wider operating temperature (–40°C to +85°C) | Higher speed and drive support demanding high-frequency bus applications but with increased power consumption | Choose for performance-critical designs needing <6ns propagation delay and >10mA drive at 5V |
Compared with SN74HC240ANSR, SN74HCT240N offers superior noise immunity in noisy 5V environments due to TTL input thresholds, while 74AC240PC delivers significantly faster switching at the cost of higher static and dynamic power - making SN74HC240ANSR optimal for balanced power/performance in industrial control and embedded memory interfaces.
Availability
SN74HC240ANSR is available at Aetrix Electronics and suitable for industrial control systems, legacy peripheral interfaces, and embedded memory subsystems requiring stable component supply and long-term obsolescence management.
Supply support for SN74HC240ANSR 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 SN74HC240 series belongs to TI's industry-standard 74HC logic family, engineered for high noise immunity, low power consumption, and seamless interoperability with legacy TTL and modern CMOS systems.
FAQ
What is the maximum operating temperature for SN74HC240ANSR?
The SN74HC240ANSR has a specified operating free-air temperature range of –40°C to +85°C. This rating applies to the PDIP package variant and is validated per JEDEC JESD78 reliability testing. Operation beyond +85°C may cause parameter drift or accelerated wear-out; thermal derating is recommended above 70°C ambient in enclosed enclosures.
Does SN74HC240ANSR support 3.3V-only operation?
Yes, SN74HC240ANSR fully supports 3.3V operation: its recommended VCC range includes 3.3V (2V–6V), input thresholds scale with VCC, and output VOH/VOL meet 3.3V logic levels (VOH ≥ 3.15V, VOL ≤ 0.33V at IOL = 6mA). No level-shifting circuitry is needed when interfacing with 3.3V microcontrollers.
How are the two 4-bit sections of SN74HC240ANSR controlled?
SN74HC240ANSR contains two independent 4-bit inverting buffer groups: pins 1OE/1A1–1A4/1Y1–1Y4 form the first section, and 2OE/2A1–2A4/2Y1–2Y4 form the second. Each OE pin controls only its associated Y outputs - allowing asynchronous enable/disable of either half-bus without affecting the other.
Can unused inputs on SN74HC240ANSR be left floating?
No. All unused inputs on SN74HC240ANSR must be tied to VCC or GND to prevent undefined logic states and excessive ICC. Floating CMOS inputs induce shoot-through current and potential oscillation. TI recommends connecting unused A inputs directly to VCC or GND using short traces - never leaving them unconnected.
What is the pin 1 marking convention for SN74HC240ANSR in PDIP packaging?
SN74HC240ANSR in PDIP-20 uses standard DIP orientation: pin 1 is located at the left end of the top row, identified by a small circular indentation or molded dot adjacent to the lead. The notch on the package body aligns with pins 1–10 (top row); counting proceeds left-to-right on top, then right-to-left on bottom.
SN74HC240ANSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74HC240ANSR FAQ
1.How can I place an order for SN74HC240ANSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC240ANSR 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 SN74HC240ANSR reliable?
The price and inventory of SN74HC240ANSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC240ANSR is usually 5 days.
3.What payment methods are accepted for SN74HC240ANSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC240ANSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC240ANSR?
SN74HC240ANSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC240ANSR 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 SN74HC240ANSR?
For technical support, including SN74HC240ANSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC240ANSR requirements.
6.How does Aetrix verify that SN74HC240ANSR is sourced from the original manufacturer or authorized distributors?
All SN74HC240ANSR 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 SN74HC240ANSR meets industry standards.
7.What is the process for return or replacement of SN74HC240ANSR?
All SN74HC240ANSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC240ANSR, 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 SN74HC240ANSR part is unused and in its original packaging.
Return procedure for SN74HC240ANSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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