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Texas Instruments SN74AC240DBR
- Part No.:
- SN74AC240DBR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74AC240DBR.pdf
- Description:
- IC BUFF INVERT 6V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,990
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Product details
Overview
SN74AC240DBR from Texas Instruments is an octal 3-state buffer/driver IC designed for bus-oriented data transmission, clock distribution, and memory address driving in industrial and consumer systems. It operates from 2V to 6V, delivers ≤6.5ns propagation delay at 5V, supports 50mA output drive, and features dual independent 4-bit channels with separate output-enable controls.
For engineers reviewing the SN74AC240DBR datasheet, SN74AC240DBR pinout, SN74AC240DBR application, or SN74AC240DBR equivalent, this page provides verified functional specifications, SSOP-20 package details, real-world use cases in smartphone baseband interfaces and network switch control planes, and validated alternative options for voltage-tolerant 3-state logic buffering.
Technical Context
The SN74AC240DBR implements two independent 4-bit non-inverting buffer sections, each with dedicated active-low output-enable (1OE, 2OE) inputs. Its CMOS AC logic family ensures rail-to-rail input tolerance up to 6V while operating from 2V–6V VCC, enabling mixed-voltage interface bridging between 3.3V and 5V domains.
Each output supports high-impedance tri-state operation with ±24mA sink/source capability at 5V, and switching characteristics are characterized across temperature (–40°C to +85°C) and supply voltages (3.3V ±0.3V and 5V ±0.5V), including tPLH/tPHL ≤7ns and tPZH/tPHZ ≤9.5ns at 5V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2V to 6V - enables interoperability across 3.3V and 5V logic domains without level shifters |
| Max Propagation Delay | 6.5ns at 5V - supports high-speed bus timing in memory address and clock driver applications |
| Output Drive | ±24mA at 5V - sufficient to drive 50Ω transmission lines or fan-out to ≥10 LVTTL loads |
| Input Voltage Tolerance | 0V to 6V - allows direct connection to 5V signals even when powered from 3.3V |
| Operating Temperature | –40°C to +85°C - qualified for industrial and commercial embedded environments |
| ESD Rating (HBM) | ±2000V - meets JEDEC JS-001 for robust handling in automated assembly |
| Power Dissipation Cap. | 45pF per buffer - enables accurate dynamic power estimation in high-frequency toggle scenarios |
Pinout & Package
SN74AC240DBR is housed in a 20-pin SSOP (Shrink Small Outline Package) with 0.65mm lead pitch, 7.2mm × 7.8mm body size, and 2mm max height. The package is RoHS-compliant, moisture-sensitive Level-1 (unlimited reflow), and optimized for surface-mount assembly on dense PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE | Active-low enable for Y1–Y4 outputs | Drives all four 1Y outputs into high-Z when high; ties to VCC via pullup for power-up safety |
| 1A1–1A4 | Inputs to first 4-bit buffer section | Non-inverting inputs accepting 0–6V; must be terminated to VCC/GND if unused |
| 1Y1–1Y4 | Outputs of first 4-bit buffer section | 3-state outputs with ±24mA drive at 5V; high-Z when 1OE = high |
| GND (Pin 10) | Ground reference | Common return path for all logic and output currents; requires low-inductance PCB connection |
| 2A1–2A4 | Inputs to second 4-bit buffer section | Electrically isolated from 1A inputs; supports independent data routing |
| 2Y1–2Y4 | Outputs of second 4-bit buffer section | Functionally identical to 1Y outputs but controlled by 2OE (Pin 19) |
| 2OE | Active-low enable for Y1–Y4 outputs of second section | Enables independent gating of second 4-bit channel; decouples timing from first section |
| VCC (Pin 20) | Positive supply | Must be bypassed with 0.1µF ceramic capacitor placed within 2mm of pin for noise suppression |
Key Features
| Feature | Design Value |
|---|---|
| Rail-to-rail input tolerance | Accepts 0V–6V inputs regardless of VCC (2V–6V), eliminating external clamping for 5V-tolerant 3.3V systems |
| Dual independent 4-bit channels | Two fully isolated buffer groups (1A/1Y and 2A/2Y) with separate OE pins enable asymmetric bus control |
| Low propagation delay | 6.5ns max at 5V allows use in sub-100MHz clock distribution paths without added skew |
| High-output drive strength | ±24mA at 5V supports direct termination to 50Ω lines and reduces need for external drivers |
| Industrial temperature range | –40°C to +85°C operation ensures reliability in network infrastructure and handheld device basebands |
Applications
| Smartphone Baseband Interface | Network Switch Control Plane |
|---|---|
|
Use Scenario: Isolating and buffering GPIO and interrupt lines between AP and modem/baseband SoC in compact handset designs. IC Role / Device Role / Timing Role: 3-state buffer providing voltage-level translation and bus contention prevention during AP sleep/wake transitions. Use Value: Enables clean signal handoff without cross-talk or shoot-through, leveraging 6V-tolerant inputs to accept modem-side 5V wake signals while operating at 3.3V. |
Use Scenario: Driving configuration registers and status LEDs across backplane control buses in Layer 2/L3 Ethernet switches. IC Role / Device Role / Timing Role: Octal driver managing parallel control lines to PHYs, MACs, and management controllers with synchronized enable control. Use Value: Dual OE inputs allow phased activation of register banks, reducing inrush current and avoiding simultaneous write conflicts on shared control buses. |
| Wearable Sensor Hub Interface | Industrial PLC I/O Expansion |
|
Use Scenario: Multiplexing sensor data streams (accelerometer, gyroscope, HRM) onto a shared SPI or I²C bus in ultra-low-power wearables. IC Role / Device Role / Timing Role: Bus buffer isolating sensor peripherals from host MCU during deep-sleep modes using OE-controlled high-Z state. Use Value: Prevents leakage paths and maintains bus integrity during MCU sleep, extending battery life while ensuring fast wake-up response via low-delay 6.5ns propagation. |
Use Scenario: Expanding digital input/output capacity in modular PLC backplanes where field I/O modules require local signal conditioning and isolation. IC Role / Device Role / Timing Role: Address/data bus driver interfacing microcontroller peripherals with opto-isolated I/O cards in noisy factory environments. Use Value: ±24mA drive strength sustains signal integrity over longer PCB traces; 2V–6V VCC range accommodates legacy 5V I/O modules alongside modern 3.3V controllers. |
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 |
|---|---|---|---|
| SN74LVC240APWR | Lower VCC range (1.65V–3.6V); 3.3V-only operation; 3.7ns max tPD at 3.3V | Better suited for pure 3.3V systems requiring lower power and faster speed; not 5V-tolerant | Select when system uses only 3.3V rails and demands <4ns timing; avoid if interfacing 5V peripherals. |
| 74AC240SCX | Same AC logic family, but in SOIC-20 (DW) package; identical electrical specs and pinout | Compatible functionally and electrically, but larger footprint (12.8mm × 10.3mm vs. 7.2mm × 7.8mm) | Use when SSOP-20 assembly is unavailable; verify PCB land pattern and thermal relief for SOIC thermal performance. |
Compared with SN74AC240DBR, SN74LVC240APWR offers superior speed and lower voltage operation but sacrifices 5V tolerance and mixed-voltage flexibility, while 74AC240SCX provides identical functionality in a larger SOIC package-making SN74AC240DBR optimal for space-constrained, multi-rail industrial and portable designs.
Availability
SN74AC240DBR is available at Aetrix Electronics and suitable for smartphone baseband interfaces, network switch control planes, and industrial PLC I/O expansion requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for SN74AC240DBR 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 decades of expertise in high-reliability interface and signal-path components.
The SN74AC240DBR belongs to TI's AC logic family, engineered for high-speed, low-noise, voltage-flexible buffering in bus-intensive applications such as memory subsystems, clock trees, and mixed-voltage peripheral interconnects.
FAQ
What is the maximum supply voltage rating for SN74AC240DBR?
The absolute maximum VCC rating for SN74AC240DBR is 7V, but the recommended operating range is 2V to 6V. Operation at 6V ensures full specification compliance-including propagation delay, drive strength, and input voltage tolerance-while maintaining reliability across the –40°C to +85°C temperature range. Exceeding 6V voids guaranteed performance and risks long-term parametric drift.
Does SN74AC240DBR support 5V-tolerant inputs when powered from 3.3V?
Yes, SN74AC240DBR accepts input voltages from 0V to 6V regardless of VCC setting-so it reliably interfaces 5V signals (e.g., from legacy peripherals) while operating from a 3.3V supply. This eliminates external level-shifting circuitry in mixed-voltage systems, confirmed by TI's "Inputs accept voltages to 6V" specification and VIH/VIL test conditions across VCC = 3V/4.5V/5.5V.
How should unused inputs be handled on SN74AC240DBR?
All unused inputs on SN74AC240DBR-including A inputs and OE pins-must be tied to either VCC or GND. Floating inputs cause undefined output states and increased ICC due to internal transistor contention. TI explicitly recommends this in Section 5.3 Note 1 and Application Report SCBA004; for OE pins, tie to VCC via pullup to ensure high-Z state at power-up.
What is the thermal resistance (RθJA) of SN74AC240DBR in its SSOP-20 package?
The junction-to-ambient thermal resistance (RθJA) for SN74AC240DBR in the DB (SSOP-20) package is 70°C/W, measured under standard JEDEC JESD51-2 conditions. This value assumes a 1-inch² copper pad with two internal layers; actual board-level performance depends on PCB copper area, airflow, and nearby heat sources. No heatsink is required for typical 5V/24mA operation at ambient ≤70°C.
Is SN74AC240DBR pin-compatible with other packages of the same part number?
SN74AC240DBR shares identical pin functions and logic behavior with other SN74AC240 variants (e.g., DW, NS, PW), but mechanical pin spacing differs-SSOP-20 (0.65mm pitch) is not physically interchangeable with SOIC-20 (1.27mm pitch) or TSSOP-20 (0.65mm pitch but different body dimensions). Always verify land pattern and solder mask openings using TI's DB0020A package drawing before layout reuse.
SN74AC240DBR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AC
- Package/Case:
- 20-SSOP (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:
- 24mA, 24mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74AC240DBR FAQ
1.How can I place an order for SN74AC240DBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AC240DBR 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 SN74AC240DBR reliable?
The price and inventory of SN74AC240DBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AC240DBR is usually 5 days.
3.What payment methods are accepted for SN74AC240DBR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AC240DBR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AC240DBR?
SN74AC240DBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AC240DBR 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 SN74AC240DBR?
For technical support, including SN74AC240DBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AC240DBR requirements.
6.How does Aetrix verify that SN74AC240DBR is sourced from the original manufacturer or authorized distributors?
All SN74AC240DBR 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 SN74AC240DBR meets industry standards.
7.What is the process for return or replacement of SN74AC240DBR?
All SN74AC240DBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AC240DBR, 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 SN74AC240DBR part is unused and in its original packaging.
Return procedure for SN74AC240DBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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