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Texas Instruments SN74AHCT240DBR
- Part No.:
- SN74AHCT240DBR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHCT240DBR.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,798
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Product details
Overview
SN74AHCT240DBR from Texas Instruments is an octal inverting buffer/driver with tri-state outputs, designed for bus-oriented receivers and transmitters in 5-V systems. It features TTL-compatible inputs (VIH = 2 V, VIL = 0.8 V), ±8 mA output drive, 9.5 ns max propagation delay (CL = 15 pF), and operates from –40°C to 125°C. It enables level translation from 3.3-V logic to 5-V buses in network switches and industrial control interfaces.
For engineers reviewing the SN74AHCT240DBR datasheet, SN74AHCT240DBR pinout, SN74AHCT240DBR application, or SN74AHCT240DBR equivalent, key selection criteria include its 20-pin SSOP package, dual 4-bit inverting tri-state architecture, guaranteed 5-V operation with 3.3-V input compatibility, and latch-up immunity exceeding 250 mA per JESD 17.
Technical Context
The SN74AHCT240DBR implements two independent 4-bit inverting buffer sections, each controlled by a dedicated output-enable (OE) input. When OE is low, inverted data passes from A inputs to Y outputs; when OE is high, all eight outputs enter high-impedance state. This architecture supports bidirectional bus isolation and memory address driving without contention.
Its CMOS design with TTL-input thresholds enables seamless interfacing between legacy 3.3-V logic and 5-V systems. Slow edge rates minimize output ringing and overshoot, while input overvoltage tolerance (up to 5.5 V) ensures robustness during mixed-voltage transitions and power sequencing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Supply Voltage | 4.5 V to 5.5 V - Ensures stable operation across standard 5-V rail tolerances and brown-out margins. |
| VOH / VOL (IOL = 8 mA) | ≥3.8 V / ≤0.44 V - Guarantees clean logic-high and logic-low levels into typical 5-V CMOS loads. |
| tPLH / tPHL (CL = 15 pF) | ≤9.5 ns - Supports reliable timing in 100-MHz bus applications with margin for trace delays. |
| Input Compatibility | TTL-level (VIH = 2 V, VIL = 0.8 V) - Directly accepts 3.3-V LVTTL outputs without level shifters. |
| Output Drive | ±8 mA per output - Sufficient for driving multiple 5-V CMOS inputs or short PCB traces. |
| Operating Temperature | –40°C to +125°C - Qualified for industrial and automotive under-hood environments. |
| ESD Rating (HBM) | ±2000 V - Meets IEC 61000-4-2 Level 2 for board-level ESD robustness. |
Pinout & Package
SN74AHCT240DBR uses a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm pitch, body size 7.50 mm × 5.30 mm, and overall footprint 7.2 mm × 7.8 mm. The package is RoHS-compliant, moisture-sensitive level 1, and rated for reflow up to 260°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1OE, 2OE | Active-low output enable controls for Group 1 (pins 2–9) and Group 2 (pins 11–18). |
| 2, 4, 6, 8 | 1A1–1A4 | Inverting input group for first 4-bit section; drives corresponding Y outputs when OE low. |
| 3, 5, 7, 9 | 2Y4–2Y1 | Inverted outputs of second 4-bit section; high-Z when 2OE high. |
| 10 | GND | Ground reference for all logic and output stages; must be low-impedance connection. |
| 11, 13, 15, 17 | 2A1–2A4 | Inverting input group for second 4-bit section; paired with Y outputs on pins 3,5,7,9. |
| 12, 14, 16, 18 | 1Y1–1Y4 | Inverted outputs of first 4-bit section; driven only when 1OE is low. |
| 20 | VCC | 5-V supply pin; requires local 0.1 µF bypass capacitor placed adjacent to pin. |
Key Features
| Feature | Design Value |
|---|---|
| Inverting tri-state buffer function | Two independent 4-bit groups allow selective bus isolation and direction control without external logic. |
| TTL-compatible input thresholds | VIH = 2 V and VIL = 0.8 V enable direct interface with 3.3-V LVTTL sources in mixed-voltage systems. |
| Slow edge rate control | Minimizes output ringing and EMI on unterminated or lightly loaded PCB traces. |
| Latch-up immunity | Exceeds 250 mA per JESD 17 - ensures survivability during transient overcurrent events. |
| Overvoltage-tolerant inputs | Accepts up to 5.5 V regardless of VCC state - simplifies hot-swap and power-sequence-critical designs. |
Applications
| Network Switch Interface | Industrial PLC Backplane |
|---|---|
Use Scenario: Isolating and buffering address/data lines between 3.3-V CPU and 5-V peripheral ASICs in Layer 2 Ethernet switch control planes. IC Role / Device Role / Timing Role: Inverting tri-state buffer providing voltage translation, bus contention prevention, and timing-controlled signal gating. Use Value: Eliminates need for discrete level shifters while maintaining <9.5 ns propagation delay for synchronous register access. |
Use Scenario: Driving 5-V optocoupler inputs from 3.3-V microcontroller GPIO in programmable logic controller I/O modules. IC Role / Device Role / Timing Role: Octal inverting driver delivering TTL-compatible logic levels with high noise immunity in electrically noisy factory environments. Use Value: ±2000 V HBM ESD rating and –40°C to 125°C operation ensure reliability in uncontrolled industrial enclosures. |
| Consumer TV Mainboard | Power Infrastructure Monitoring |
Use Scenario: Buffering HDMI CEC and IR receiver signals between SoC and front-panel control ICs in smart television platforms. IC Role / Device Role / Timing Role: Signal conditioner enabling bidirectional communication with precise enable timing and low-output ringing. Use Value: Dual OE pins allow independent control of upstream/downstream signal paths, reducing firmware complexity. |
Use Scenario: Interfacing isolated ADC SPI buses to 5-V FPGA configuration logic in solar inverter monitoring subsystems. IC Role / Device Role / Timing Role: Tri-state level translator ensuring clean clock/data edges across isolation barriers without added jitter. Use Value: Input capacitance of 10 pF and 2.5 pF output capacitance minimize loading on high-impedance sensor interface lines. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AHCT240PW | TSSOP-20 package (6.5 mm × 6.4 mm); higher RθJA (116.8°C/W) than DBR's 99.9°C/W. | Better suited for space-constrained layouts but requires more thermal margin at full load. | Choose PW for ultra-dense boards where SSOP footprint is prohibitive; verify thermal derating above 60°C ambient. |
| SN74LVC240APWR | 3.3-V supply only (1.65–3.6 V); non-inverting logic; lower drive (±24 mA) and faster speed (tPD = 5.5 ns). | Not compatible for 5-V bus translation; requires separate level-shifting circuitry for 5-V interfaces. | Select only for pure 3.3-V domains; avoid when interfacing to legacy 5-V peripherals or memory subsystems. |
Compared with SN74AHCT240PW and SN74LVC240APWR, SN74AHCT240DBR uniquely combines 5-V operation, TTL input compatibility, and SSOP packaging-making it the only drop-in solution for retrofitting 3.3-V logic into existing 5-V industrial backplanes without layout changes.
Availability
SN74AHCT240DBR is available at Aetrix Electronics and suitable for network switches, industrial PLC backplanes, and consumer TV mainboards requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SN74AHCT240DBR 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 connectivity technologies, with decades of experience in industrial-grade logic and interface solutions.
SN74AHCT240DBR belongs to the SNx4AHCT logic family, engineered for robust 5-V bus interfacing in harsh environments-emphasizing voltage translation, ESD resilience, and thermal stability over raw speed.
FAQ
What is the maximum operating temperature for SN74AHCT240DBR?
The SN74AHCT240DBR is rated for continuous operation from –40°C to +125°C ambient temperature. This specification is validated per JEDEC standards and applies to the DB (SSOP-20) package variant. Thermal derating is not required within this range when mounted on standard FR-4 PCBs with recommended copper pour and 0.1 µF local bypassing at VCC.
Does SN74AHCT240DBR support 3.3-V input logic levels?
Yes, SN74AHCT240DBR accepts 3.3-V logic inputs directly: its VIH threshold is 2.0 V minimum and VIL is 0.8 V maximum, fully compatible with LVTTL and 3.3-V CMOS outputs. No external level-shifting circuitry is needed when driving the device from 3.3-V microcontrollers or FPGAs.
Can SN74AHCT240DBR be used as a non-inverting buffer?
No-SN74AHCT240DBR is strictly an inverting octal buffer. Each A input drives a complementary Y output (e.g., 1A1 → 1Y1 with inversion). For non-inverting functionality, TI recommends SN74AHCT244DBR, which shares identical pinout, package, and electrical specs but provides true (non-inverting) buffering.
What is the recommended bypass capacitor for SN74AHCT240DBR?
A 0.1 µF ceramic capacitor placed as close as possible to the VCC pin (pin 20) and GND (pin 10) is mandatory for stable operation. TI further recommends adding a 1.0 µF bulk capacitor nearby to suppress low-frequency supply noise, especially in systems with multiple logic devices sharing the same 5-V rail.
Is SN74AHCT240DBR pin-compatible with other AHCT240 variants?
Yes-SN74AHCT240DBR is pin-compatible with all 20-pin AHCT240 packages (e.g., DW, NS, PW, N) sharing the same functional pinout: dual OE controls, interleaved A/Y assignments, and standard VCC/GND placement. Mechanical dimensions differ, but PCB layout remains identical across DB, DW, NS, and PW footprints.
SN74AHCT240DBR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- 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:
- 8mA, 8mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74AHCT240DBR FAQ
1.How can I place an order for SN74AHCT240DBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT240DBR 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 SN74AHCT240DBR reliable?
The price and inventory of SN74AHCT240DBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT240DBR is usually 5 days.
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SN74AHCT240DBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT240DBR 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 SN74AHCT240DBR?
For technical support, including SN74AHCT240DBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT240DBR requirements.
6.How does Aetrix verify that SN74AHCT240DBR is sourced from the original manufacturer or authorized distributors?
All SN74AHCT240DBR 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 SN74AHCT240DBR meets industry standards.
7.What is the process for return or replacement of SN74AHCT240DBR?
All SN74AHCT240DBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT240DBR, 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 SN74AHCT240DBR part is unused and in its original packaging.
Return procedure for SN74AHCT240DBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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