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Texas Instruments SN74S240N
- Part No.:
- SN74S240N
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74S240N.pdf
- Description:
- IC BUFFER INVERT 5.25V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:188
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Product details
Overview
SN74S240N from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for memory address and bus driving applications in TTL-compatible systems. It features two independent 4-bit channels (1A→1Y, 2A→2Y), active-low output-enable inputs (1G, 2G/2G), 7 ns typical propagation delay at 5 V, ±64 mA output drive capability, and operates over 0°C to 70°C.
For engineers reviewing the SN74S240N datasheet, SN74S240N pinout, SN74S240N application, or SN74S240N equivalent, this page delivers verified electrical specs, functional pin mapping, real-world use cases in bus buffering and memory addressing, and validated alternative parts for design continuity and sourcing flexibility.
Technical Context
The SN74S240N implements Schottky transistor logic (S-TTL) with PNP input stages that reduce DC loading on driven buses and built-in input hysteresis (0.2–0.4 V) to improve noise immunity. Its dual-channel architecture supports independent enable control per 4-bit group, enabling bidirectional bus management without contention when one channel is enabled and the other disabled.
It delivers high-current 3-state outputs capable of driving terminated lines down to 133 Ω and exhibits fast switching: tPLH/tPHL = 4.5–7 ns (RL = 90 Ω, CL = 50 pF), with tPZL/tPZH ≤15 ns. Power consumption is higher than LS variants-ICC up to 135 mA (outputs high) -reflecting its S-TTL speed-power trade-off.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | Schottky TTL (S-TTL), compatible with standard TTL and LSTTL interfaces |
| Propagation Delay (tPLH/tPHL) | 4.5–7 ns @ VCC = 5 V, RL = 90 Ω, CL = 50 pF - enables high-speed memory/address bus timing |
| Output Drive (IOL/IOH) | 64 mA sink / –15 mA source - drives heavy capacitive loads and terminated transmission lines |
| Input Hysteresis | 0.2–0.4 V - increases noise margin on shared bus lines in electrically noisy environments |
| Supply Voltage Range | 4.75 V to 5.25 V - tight tolerance ensures stable operation in regulated 5-V systems |
| Operating Temperature | 0°C to +70°C - commercial-grade rating suitable for industrial and telecom infrastructure |
| ESD Rating (HBM) | 500 V - meets JEDEC JS-001 for safe handling in standard manufacturing environments |
Pinout & Package
SN74S240N is supplied in a 20-pin plastic dual in-line package (PDIP-N), body size 24.33 mm × 6.35 mm, with through-hole mounting and standard 0.3-inch row spacing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1G, 2G/2G | Active-low output-enable inputs - independently disable Channel 1 (pins 1–9, 12, 14, 16, 18) or Channel 2 (pins 11, 13, 15, 17, 3, 5, 7, 9) |
| 2, 4, 6, 8 | 1A1–1A4 | Inverting input data lines for Channel 1 - each drives corresponding 1Y output with inversion |
| 11, 13, 15, 17 | 2A1–2A4 | Inverting input data lines for Channel 2 - identical function to 1Ax but controlled by 2G |
| 12, 14, 16, 18 | 1Y1–1Y4 | Inverting 3-state outputs for Channel 1 - high-impedance when 1G = HIGH |
| 3, 5, 7, 9 | 2Y1–2Y4 | Inverting 3-state outputs for Channel 2 - high-impedance when 2G = HIGH |
| 10 | GND | Ground reference for all logic and power connections |
| 20 | VCC | +5 V power supply - must be decoupled locally with 0.1 µF ceramic capacitor |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 4-bit inverting buffers | Enables simultaneous or staggered control of two memory/address sub-buses without inter-channel coupling |
| PNP input structure | Reduces DC input current (IIL = –400 µA max), minimizing loading on upstream drivers and improving fan-out |
| Input hysteresis (0.2–0.4 V) | Rejects bus noise up to ±200 mV, preventing false toggling in high-noise server or telecom backplane environments |
| High-current 3-state outputs | 64 mA sink capability allows direct driving of unterminated PCB traces up to 15 cm or 133-Ω terminated lines |
| Compatible with 3.3-V and 5-V logic | Inputs tolerate VIH ≥ 2 V and VIL ≤ 0.8 V - supports mixed-voltage system interfacing without level shifters |
Applications
| Memory Address Buffering | System Bus Driver |
|---|---|
|
Use Scenario: Driving 16-bit memory address lines from a microprocessor or address latch across a 10-cm PCB trace to SRAM/ROM chips. IC Role / Device Role / Timing Role: Inverting 3-state buffer providing signal integrity, noise immunity, and bus isolation during DMA cycles. Use Value: 7 ns propagation delay and 64 mA drive ensure setup/hold timing margins are met even with 50 pF net capacitance. |
Use Scenario: Isolating and strengthening control signals (RD, WR, IO/M) between CPU and peripheral I/O chips on a legacy industrial controller board. IC Role / Device Role / Timing Role: Dual-channel bus driver enabling independent enable/disable of read vs. write signal groups. Use Value: Independent 1G/2G pins allow precise timing control - e.g., disable write drivers while read drivers remain active. |
| LED Display Multiplexing | Telecom Line Repeater |
|
Use Scenario: Driving common-anode 7-segment LED displays in multiplexed configurations requiring high sink current per segment. IC Role / Device Role / Timing Role: Inverting buffer acting as column driver with 64 mA per output to illuminate multiple segments simultaneously. Use Value: High sink current eliminates need for external transistors, reducing BOM count and layout area in space-constrained front panels. |
Use Scenario: Restoring signal integrity on long backplane traces (>20 cm) between line cards in a telecom switch chassis. IC Role / Device Role / Timing Role: Signal repeater with hysteresis-enhanced noise rejection on differential-like single-ended control lines. Use Value: Input hysteresis and fast 7 ns switching maintain edge fidelity and prevent metastability in clock-synchronous control paths. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS240N | Lower drive (24 mA sink), slower speed (14 ns tPLH), lower ICC (44 mA), LS-TTL family | Better suited for low-power, noise-sensitive applications where speed <10 MHz is acceptable | Select SN74LS240N when thermal budget or static power is constrained and 7 ns speed is unnecessary |
| SN74F240N | Fast TTL family: 3.5 ns tPLH, 45 mA IOL, higher ICC (100 mA), no input hysteresis | Requires stricter layout control due to faster edges; less tolerant of bus noise without external filtering | Choose SN74F240N only when sub-5 ns timing is mandatory and noise environment is tightly controlled |
Compared with SN74LS240N and SN74F240N, the SN74S240N uniquely balances speed (7 ns), drive strength (64 mA), and noise immunity (hysteresis), making it optimal for robust bus driving in mixed-signal telecom and industrial systems where reliability trumps minimal power or absolute speed.
Availability
SN74S240N is available at Aetrix Electronics and suitable for memory address buffering, system bus driving, LED display multiplexing, and telecom line repeater applications requiring stable component supply, long-term obsolescence management, and traceable sourcing.
Supply support for SN74S240N 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 delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74S240N belongs to TI's legacy S-TTL logic family, engineered specifically for high-speed, high-drive bus interface and memory addressing in 5-V digital systems where signal integrity and noise resilience are critical.
FAQ
What is the maximum operating temperature for the SN74S240N?
The SN74S240N is rated for commercial temperature operation from 0°C to +70°C. This range is specified in the Recommended Operating Conditions table of the official TI datasheet (SDLS144D). Operation outside this range may result in parametric degradation or functional failure. For extended temperature applications, consider the military-grade SN54S240J variant rated from –55°C to +125°C.
Does the SN74S240N support 3.3-V input logic levels?
Yes, the SN74S240N accepts 3.3-V logic inputs reliably. Its VIH(min) is 2.0 V and VIL(max) is 0.8 V under recommended conditions, allowing direct interfacing with 3.3-V CMOS outputs without level shifting. This compatibility is explicitly confirmed in the "Features" section of the TI datasheet and validated across the SNx4S24x family.
How does the SN74S240N differ from the SN74LS240N in practical use?
The SN74S240N offers significantly faster propagation delay (7 ns vs. 14 ns), higher output drive (64 mA vs. 24 mA), and greater power consumption (135 mA vs. 44 mA ICC). It also includes input hysteresis for improved noise immunity - a feature absent in the LS variant. These differences make the SN74S240N preferable in timing-critical, high-noise, or high-capacitance bus applications.
What is the purpose of the hysteresis specification in the SN74S240N?
The SN74S240N incorporates 0.2–0.4 V of input hysteresis (VT+ − VT−) to increase noise margin on bus lines. This prevents false triggering caused by slow-rising/falling edges or electrical noise, especially in shared-bus environments like server backplanes or industrial control racks. The hysteresis is inherent to the S-TTL input stage and requires no external components.
Can the SN74S240N drive a 133-Ω terminated line?
Yes, the SN74S240N is explicitly characterized to drive terminated lines down to 133 Ω, as stated in the device description section of the TI datasheet. Its 64 mA sink capability and fast edge rates ensure signal integrity on such loads, making it suitable for impedance-controlled routing in telecom and networking hardware where termination is standard practice.
SN74S240N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74S
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- 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:
- 15mA, 64mA
- Voltage - Supply:
- 4.75V ~ 5.25V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74S240N FAQ
1.How can I place an order for SN74S240N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74S240N 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 SN74S240N reliable?
The price and inventory of SN74S240N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74S240N is usually 5 days.
3.What payment methods are accepted for SN74S240N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74S240N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74S240N?
SN74S240N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74S240N 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 SN74S240N?
For technical support, including SN74S240N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74S240N requirements.
6.How does Aetrix verify that SN74S240N is sourced from the original manufacturer or authorized distributors?
All SN74S240N 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 SN74S240N meets industry standards.
7.What is the process for return or replacement of SN74S240N?
All SN74S240N units undergo pre-shipment inspection (PSI). If there is an issue with SN74S240N, 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 SN74S240N part is unused and in its original packaging.
Return procedure for SN74S240N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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