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Texas Instruments SN74BCT240DWR
- Part No.:
- SN74BCT240DWR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74BCT240DWR.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,956
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Product details
Overview
SN74BCT240DWR from Texas Instruments is an octal noninverting buffer/driver with 3-state outputs, designed for memory address and bus driving 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 SN74BCT240DWR datasheet, SN74BCT240DWR pinout, SN74BCT240DWR application, or SN74BCT240DWR equivalent, key selection criteria include 3-state bus interface capability, TTL-level input compatibility, SOIC-20 package thermal performance (θJA = 58°C/W), and guaranteed operation across 0°C to 70°C industrial temperature range.
Technical Context
This device integrates eight independent noninverting buffers, each with active-low 3-state output enable (OE). Two separate OE inputs (1OE and 2OE) control four buffers each, enabling grouped bus isolation. The BiCMOS process reduces quiescent supply current (ICCZ) while maintaining TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2.0 V) and robust output drive.
Switching behavior is characterized under 50-pF load and 500-Ω source impedance, with tPZH/tPZL (enable-to-output) delays of 1–8.8 ns and tPHZ/tPLZ (disable-to-output) delays of 1–10.5 ns. ESD protection exceeds 2000-V HBM, and absolute maximum ratings include 7-V input tolerance and –0.5 V to 5.5 V disabled-output voltage range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures compatibility with standard 5-V TTL and CMOS logic rails. |
| Output Drive | IOL = 64 mA / IOH = –15 mA - Sustains heavy bus loading without signal degradation. |
| Propagation Delay | tPHL = 0.4 ns (min), tPLH = 0.5 ns (min) - Enables high-speed address/data buffering in fast memory systems. |
| 3-State Enable Delay | tPZH = 1 ns (min), tPZL = 1 ns (min) - Supports rapid bus arbitration and multi-master timing. |
| Input Thresholds | VIH = 2.0 V, VIL = 0.8 V - Guarantees reliable interfacing with legacy TTL and LVTTL sources. |
| Quiescent Current | ICCZ = 6–9 mA - Minimizes power during 3-state hold, critical for low-idle-bus applications. |
| ESD Rating | 2000-V HBM - Meets JESD22-A114A for robust handling in manufacturing and field environments. |
Pinout & Package
SN74BCT240DWR uses a 20-pin SOIC (DW) package with 7.5-mm body width, 2.65-mm max height, and 1.27-mm lead pitch. Pin 1 is marked by a beveled corner or notch; the package is RoHS-compliant with NiPdAu lead finish and MSL Level-1 rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 2OE | Active-low output enable | Independent group control: 1OE enables Y1–Y4, 2OE enables Y5–Y8 (labeled 2Y1–2Y4). |
| 1A1–1A4, 2A1–2A4 | Buffer inputs | Eight noninverting data inputs, TTL-compatible, with clamp diodes for overvoltage protection. |
| 1Y1–1Y4, 2Y1–2Y4 | 3-state buffered outputs | Eight totem-pole outputs; high-impedance when respective OE is high. |
| VCC | Power supply | Connects to 4.5–5.5 V rail; decoupling capacitor required near pin 20. |
| GND | Ground reference | Common return path for all signals and supply; connects to system ground plane at pin 10. |
Key Features
| Feature | Design Value |
|---|---|
| BiCMOS output stage | Combines bipolar speed and CMOS low ICCZ, reducing power by >50% vs. pure bipolar equivalents. |
| Grouped 3-state control | Dual OE inputs allow independent enable/disable of two 4-bit buffer banks for flexible bus partitioning. |
| TTL-compatible inputs | Accepts standard TTL logic levels without level-shifting, simplifying integration into mixed-logic systems. |
| High fan-out capability | Drives up to 15 LSTTL loads per output, supporting dense memory address or data bus topologies. |
| Power-up 3-state safety | OE tied to VCC via pullup ensures high-impedance state at power-on, preventing bus contention. |
Applications
| Memory Address Buffering | Bus Transceiver Interface |
|---|---|
Use Scenario: Driving 16-bit address lines from a microcontroller to multiple SRAM or EPROM chips on a shared bus. IC Role / Device Role / Timing Role: Noninverting buffer with 3-state outputs isolates address latches during DMA cycles and prevents bus contention. Use Value: 64-mA sink capability ensures clean edges across long traces; tPHL < 4 ns maintains setup/hold timing margins at 20-MHz bus rates. | Use Scenario: Bidirectional data bus isolation between a CPU and peripheral ASIC in a modular backplane system. IC Role / Device Role / Timing Role: One-directional driver controlled by system bus controller OE signals to enforce unidirectional data flow per transaction phase. Use Value: Dual OE inputs allow synchronized enable of upper/lower byte lanes; tPZH < 8 ns enables sub-100-ns bus turnaround. |
| Clock Distribution Fanout | Legacy System Bus Extension |
Use Scenario: Distributing a 5-V clock signal from a PLD to eight synchronous logic blocks with matched trace lengths. IC Role / Device Role / Timing Role: Low-skew buffer replicating clock with identical edge rates across all outputs. Use Value: Propagation delay matching ≤ 1.5 ns (tPLH–tPHL) minimizes clock skew; 11-pF output capacitance stabilizes edge integrity. | Use Scenario: Interfacing modern FPGA I/O banks to legacy ISA or VME bus peripherals requiring 5-V TTL signaling. IC Role / Device Role / Timing Role: Level-shifting and drive-strengthening buffer for FPGA outputs lacking native 5-V tolerance or current capability. Use Value: VIH/VIL thresholds match TTL specs exactly; 64-mA drive sustains signal integrity over 15-cm ribbon cables with stubs. |
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 |
|---|---|---|---|
| SN74ACT240N | CMOS-based, 4.5–5.5 V supply, lower ICCZ (2 µA), but reduced output drive (24 mA) | Better for low-power, low-noise systems; insufficient for heavy bus loads or long traces | Choose when power budget is critical and bus capacitance < 30 pF |
| SN74LS240N | Bipolar TTL, 4.75–5.25 V, higher ICC (40 mA), slower delays (tPLH up to 25 ns) | Compatible with legacy LS designs but lacks BiCMOS speed and efficiency | Use only for drop-in replacement in existing LS-based boards with no timing margin constraints |
Compared with SN74ACT240N and SN74LS240N, the SN74BCT240DWR uniquely balances high-speed switching (sub-5 ns delays), strong bus drive (64 mA), and moderate quiescent current (6–9 mA), making it optimal for industrial memory and bus interfaces where both performance and reliability are required.
Availability
SN74BCT240DWR is available at Aetrix Electronics and suitable for memory address buffering, bus transceiver interfaces, clock distribution, and legacy system bus extension requiring stable component supply and industrial-temperature operation.
Supply support for SN74BCT240DWR 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 SN74BCT240DWR belongs to TI's 'BCT logic family, engineered for high-speed, high-drive 3-state bus interfacing in 5-V systems where BiCMOS efficiency and TTL compatibility are essential.
FAQ
What is the recommended power-up sequence for SN74BCT240DWR to avoid bus contention?
TI specifies that OE pins must be held high (disabled) during power-up to ensure all outputs remain in high-impedance state until system control logic is ready. Tie 1OE and 2OE to VCC through a 10-kΩ pullup resistor; minimum value depends on driver sink capability but ≥4.7 kΩ is typical. This prevents unintended output activation before VCC stabilizes and control signals settle. The SN74BCT240DWR does not include internal power-on reset, so external OE management is mandatory.
Can SN74BCT240DWR drive a 50-pF bus load at 10 MHz without signal integrity issues?
Yes - the SN74BCT240DWR is characterized with CL = 50 pF and R1/R2 = 500 Ω, delivering tPLH/tPHL < 5.6 ns and clean edges. Its 64-mA sink strength and 11-pF typical output capacitance maintain rise/fall times < 3 ns under this load. For sustained 10-MHz operation, ensure proper PCB layout: minimize trace length, use ground plane, and place 0.1-µF ceramic decoupling capacitors within 5 mm of VCC/GND pins. The SN74BCT240DWR's BiCMOS design inherently suppresses ringing better than pure bipolar drivers.
Does SN74BCT240DWR support mixed-voltage interfacing, such as 3.3-V microcontrollers driving its inputs?
No - the SN74BCT240DWR requires VIH ≥ 2.0 V and VIL ≤ 0.8 V for valid logic recognition, which aligns with 5-V TTL, not 3.3-V CMOS. A 3.3-V microcontroller output (VOH ≈ 3.3 V) meets VIH but may fall below noise margin; direct connection risks marginal switching. Use a level translator (e.g., TXB0108) or a resistor divider + Schmitt trigger if interfacing with 3.3-V logic. The SN74BCT240DWR itself has no internal level-shifting capability and must operate with 4.5–5.5 V supply to meet its input threshold specs.
What is the thermal resistance (θJA) of SN74BCT240DWR in its SOIC-20 package, and how does it affect continuous operation?
The SN74BCT240DWR in SOIC-20 (DW) package has θJA = 58°C/W, measured per JESD51-7 on a 1-in² 2-layer board with 2-oz copper. At maximum rated ICC = 71 mA and VCC = 5.5 V, worst-case power dissipation is ~390 mW, resulting in ~22.6°C junction-to-ambient rise above ambient. With 70°C max ambient, junction temperature stays below 125°C. For high-density layouts or elevated ambient, add thermal vias under the exposed pad (if present) or reduce output loading - the SN74BCT240DWR's BiCMOS process inherently lowers dynamic heating versus LS equivalents.
Are the 3-state outputs of SN74BCT240DWR compatible with hot-swap or live-insertion scenarios?
Not inherently - the SN74BCT240DWR lacks bus-hold, power-off protection, or Ioff circuitry. When VCC is removed while inputs remain active, outputs may enter undefined states or conduct excessive current. For hot-swap use, add series current-limiting resistors (e.g., 100 Ω) on all outputs and ensure OE is actively driven low before insertion. TI recommends using dedicated hot-swap buffers (e.g., SN74CBT3244) instead. The SN74BCT240DWR's 2000-V HBM ESD rating helps withstand handling discharge but does not guarantee live-insertion robustness.
SN74BCT240DWR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74BCT
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74BCT240DWR FAQ
1.How can I place an order for SN74BCT240DWR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74BCT240DWR 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 SN74BCT240DWR reliable?
The price and inventory of SN74BCT240DWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT240DWR is usually 5 days.
3.What payment methods are accepted for SN74BCT240DWR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74BCT240DWR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74BCT240DWR?
SN74BCT240DWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74BCT240DWR 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 SN74BCT240DWR?
For technical support, including SN74BCT240DWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT240DWR requirements.
6.How does Aetrix verify that SN74BCT240DWR is sourced from the original manufacturer or authorized distributors?
All SN74BCT240DWR 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 SN74BCT240DWR meets industry standards.
7.What is the process for return or replacement of SN74BCT240DWR?
All SN74BCT240DWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT240DWR, 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 SN74BCT240DWR part is unused and in its original packaging.
Return procedure for SN74BCT240DWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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