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Texas Instruments SN74BCT240N
- Part No.:
- SN74BCT240N
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74BCT240N.pdf
- Description:
- IC BUFFER INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,212
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Product details
Overview
SN74BCT240N from Texas Instruments is an octal noninverting buffer/driver with 3-state outputs, designed for memory address driving, clock distribution, and bus interfacing in 5-V TTL-compatible systems. It operates from 4.5 V to 5.5 V, delivers ±64 mA output drive (IOL/IOH), features BiCMOS architecture for low ICCZ (6–9 mA), and supports high-speed propagation delays as low as 0.4 ns (tPHL) and 0.5 ns (tPLH).
For engineers reviewing the SN74BCT240N datasheet, SN74BCT240N pinout, SN74BCT240N application, or SN74BCT240N equivalent, key selection criteria include 3-state bus contention control, TTL-level input compatibility, 20-pin PDIP package thermal performance (θJA = 69°C/W), and guaranteed operation across 0°C to 70°C industrial temperature range.
Technical Context
The SN74BCT240N integrates two independent 4-bit noninverting buffer sections, each with active-low 3-state enable (1OE, 2OE). Its BiCMOS design combines bipolar input stages for TTL-level recognition and CMOS output stages for high current drive and low quiescent power in disabled state.
Each output supports symmetrical 3-state control with fast enable/disable timing (tPZH/tPLZ ≤ 8.1 ns, tPZL/tPLZ ≤ 10.5 ns at VCC = 4.5–5.5 V), and logic inputs tolerate voltages up to 7 V-enabling safe interfacing with higher-voltage peripherals without level shifters.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures robust operation across noisy 5-V rails and brown-out margins. |
| Output Drive (IOL) | 64 mA - Sinks sufficient current to drive multiple TTL loads or terminate stubs on parallel buses. |
| Propagation Delay (tPHL) | 0.4 ns (min) - Enables sub-nanosecond timing-critical address or clock buffering in high-speed memory subsystems. |
| 3-State Enable Time (tPZH) | 1 ns (min) - Guarantees rapid bus release to prevent data contention during multiplexed access cycles. |
| Input Clamp Current | –18 mA - Protects inputs against transient overvoltage events per JESD 22 A114-A (2000-V HBM). |
| Quiescent ICCZ | 6–9 mA - Reduces standby power in 3-state-bus architectures compared to legacy TTL buffers. |
| Package Thermal Impedance | 69°C/W (PDIP-N) - Supports continuous operation at full load in ambient temperatures up to 70°C without forced cooling. |
Pinout & Package
SN74BCT240N uses a 20-pin plastic dual in-line package (PDIP-N) with 0.3-inch body width and standard through-hole mounting. Pin 1 is located at the top-left corner (notch-side indicator), with pins numbered counter-clockwise.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 2OE | Active-low output-enable control | Disables both 4-bit sections simultaneously; must be pulled high via resistor during power-up to ensure Hi-Z default state. |
| 1A1–1A4, 2A1–2A4 | Noninverting input terminals | Accept TTL-compatible logic levels (VIH ≥ 2 V, VIL ≤ 0.8 V); tolerant to 7-V input transients. |
| 1Y1–1Y4, 2Y1–2Y4 | 3-state buffered outputs | Drive bus lines directly; sink/source up to 64 mA/–15 mA while maintaining VOH ≥ 2.0 V and VOL ≤ 0.55 V. |
| VCC, GND | Power supply and reference | Single 5-V rail only; decoupling capacitor required at VCC pin to suppress switching noise coupling into logic paths. |
Key Features
| Feature | Design Value |
|---|---|
| BiCMOS process technology | Combines TTL input compatibility with CMOS output drive strength and low ICCZ, eliminating need for external pull-ups on 3-state control lines. |
| High fan-out capability | Drives ≥10 standard TTL loads per output, enabling direct connection to memory address latches or peripheral I/O buffers without intermediate drivers. |
| ESD protection | Exceeds 2000-V Human-Body Model (JESD 22-A114-A), allowing safe handling and board-level integration without additional ESD suppression components. |
| Bus-hold circuitry | Not integrated - unused inputs must be externally tied to VCC or GND per SCBA004 to prevent floating-node oscillation and increased ICC. |
| Symmetrical OE inputs | 1OE and 2OE share identical electrical characteristics (VIH/VIL, timing), simplifying PCB layout and enabling synchronized bus arbitration across both 4-bit sections. |
Applications
| Memory Address Buffering | System Clock Distribution |
|---|---|
|
Use Scenario: Driving 16-bit address bus between microprocessor and SRAM/ROM chips in embedded controllers. IC Role / Device Role / Timing Role: Noninverting buffer isolating CPU address outputs from capacitive bus loading; enables clean edge transitions at >20 MHz clock rates. Use Value: Prevents address skew and setup-time violations by delivering 64-mA sink current to overcome trace capacitance and multiple device inputs. |
Use Scenario: Distributing a master system clock to multiple peripheral ICs (UART, timer, ADC) with matched skew. IC Role / Device Role / Timing Role: Low-skew clock driver with identical tPLH/tPHL paths across all eight outputs, minimizing inter-channel jitter. Use Value: Achieves <0.5 ns channel-to-channel skew, supporting synchronous sampling of time-critical analog signals at 50+ MSPS. |
| ISA Bus Interface Logic | Legacy Peripheral Expansion |
|
Use Scenario: Interfacing modern microcontrollers to ISA-bus expansion cards requiring TTL-level address/data strobes. IC Role / Device Role / Timing Role: Bidirectional bus transceiver replacement using 3-state control to manage direction and contention on shared data lines. Use Value: Eliminates need for discrete transceivers by providing controlled Hi-Z isolation and 64-mA drive for legacy 8-bit data bus termination. |
Use Scenario: Adding parallel port functionality to industrial PLC modules using legacy printer-port protocols. IC Role / Device Role / Timing Role: Output latch driver for 8-bit status/control signals (STROBE, ACK, BUSY) with simultaneous assertion capability. Use Value: Delivers deterministic 3.5-ns max tPHL delay and 0.55-V max VOL under 64-mA load, ensuring reliable handshake timing with mechanical printers and scanners. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal 3-state buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS240N | Lower drive (IOL = 24 mA), higher ICC (48–71 mA), slower tPHL (15 ns min), TTL-only process. | Compatible in static 5-V systems but unsuitable for high-speed bus loading or low-power designs. | Select when cost sensitivity outweighs speed/power requirements and legacy LS logic families dominate the BOM. |
| SN74ACT240N | Wider VCC range (4.5–5.5 V), CMOS input (VIH = 3.5 V), lower ICCZ (1 µA), same pinout. | Requires level-shifting for TTL input sources; superior noise immunity but incompatible with direct TTL fan-in. | Prefer for mixed-signal systems where CMOS input thresholds and ultra-low standby current are critical. |
Compared with SN74LS240N and SN74ACT240N, the SN74BCT240N uniquely balances TTL input compatibility, 64-mA drive, and BiCMOS efficiency-making it optimal for upgrading legacy bus interfaces without redesigning input signal conditioning or compromising timing margins.
Availability
SN74BCT240N is available at Aetrix Electronics and suitable for memory subsystem buffering, industrial bus interface design, and legacy system upgrades requiring stable component supply and long-term obsolescence management.
Supply support for SN74BCT240N 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 90 years of innovation in industrial, automotive, and communications markets.
The SN74BCT240N belongs to TI's 'BCT logic family-engineered for high-density, high-performance 3-state bus interfacing in 5-V systems where TTL compatibility, drive strength, and power efficiency are jointly critical.
FAQ
What is the maximum operating temperature range for the SN74BCT240N?
The SN74BCT240N is rated for industrial operation from 0°C to +70°C. This range is validated per TI's recommended operating conditions and supported by thermal characterization (θJA = 69°C/W in PDIP-N package), making it suitable for enclosed control panels and non-ventilated embedded enclosures without active cooling.
Does the SN74BCT240N require external pull-up resistors on its OE pins?
Yes-the SN74BCT240N OE inputs are active-low and lack internal pull-ups. To guarantee high-impedance outputs during power-up or reset, 1OE and 2OE must be tied to VCC via external pull-up resistors. The minimum resistance value depends on the driver's current-sinking capability, as specified in TI's application guidance (SCBA004).
Can the SN74BCT240N drive standard TTL loads directly?
Yes-the SN74BCT240N is explicitly designed for TTL compatibility. Its outputs deliver 64 mA sink current and –15 mA source current while maintaining VOH ≥ 2.0 V and VOL ≤ 0.55 V, meeting or exceeding standard TTL fan-out requirements (≥10 loads) without external buffering.
Is the SN74BCT240N pin-compatible with other '240-series devices like SN74LS240 or SN74ACT240?
Yes-the SN74BCT240N shares identical 20-pin PDIP pinout and functional mapping (1A1–1Y4, 2A1–2Y4, 1OE, 2OE, VCC, GND) with SN74LS240N and SN74ACT240N. However, electrical differences (drive strength, input thresholds, ICC) require validation in the target circuit before substitution.
What is the purpose of the BiCMOS design in the SN74BCT240N?
The BiCMOS architecture in the SN74BCT240N merges bipolar transistor inputs for robust TTL-level recognition (VIH = 2 V, VIL = 0.8 V) with CMOS output stages for high current drive (64 mA) and low quiescent power (ICCZ = 6–9 mA). This eliminates trade-offs between speed, power, and compatibility found in pure bipolar or CMOS alternatives.
SN74BCT240N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74BCT
- 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:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74BCT240N FAQ
1.How can I place an order for SN74BCT240N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74BCT240N 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 SN74BCT240N reliable?
The price and inventory of SN74BCT240N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT240N is usually 5 days.
3.What payment methods are accepted for SN74BCT240N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74BCT240N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74BCT240N?
SN74BCT240N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74BCT240N 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 SN74BCT240N?
For technical support, including SN74BCT240N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT240N requirements.
6.How does Aetrix verify that SN74BCT240N is sourced from the original manufacturer or authorized distributors?
All SN74BCT240N 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 SN74BCT240N meets industry standards.
7.What is the process for return or replacement of SN74BCT240N?
All SN74BCT240N units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT240N, 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 SN74BCT240N part is unused and in its original packaging.
Return procedure for SN74BCT240N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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