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Texas Instruments SN74AHCT540DBR
- Part No.:
- SN74AHCT540DBR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHCT540DBR.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,783
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Product details
Overview
SN74AHCT540DBR from Texas Instruments is an octal noninverting buffer/driver with 3-state outputs, designed for bus line driving and memory address register buffering in 5-V digital systems. It features TTL-compatible inputs, ±8 mA output drive, 4.4 V minimum VOH at 4.5 V VCC, and dual active-low output-enable controls (OE1/OE2) enabling independent control of two groups of four channels.
For engineers reviewing the SN74AHCT540DBR datasheet, SN74AHCT540DBR pinout, SN74AHCT540DBR application, or SN74AHCT540DBR equivalent, key selection criteria include 3-state timing (tPZH ≤ 9 ns), latch-up immunity (>250 mA), ESD robustness (±2000 V HBM), and SSOP-20 package compatibility with high-density PCB layouts.
Technical Context
The SN74AHCT540DBR implements dual 4-bit noninverting buffers with independent 3-state control logic: OE1 enables Y1–Y4, OE2 enables Y5–Y8. Each output enters high-impedance when its respective OE is high, supporting bidirectional bus contention management. The device uses standard CMOS circuitry with TTL-level input thresholds (VIH = 2 V, VIL = 0.8 V).
Its propagation delay (tPLH/tPHL = 6.0 ns typ. at CL = 50 pF) and enable/disable times (tPZH/tPLZ = 8.0 ns typ.) are specified across –40°C to 125°C, ensuring reliable operation in industrial environments. Power dissipation is minimized via low ICC (4 µA typ.) and Cpd (12 pF), making it suitable for low-noise, low-power bus interface applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Supply | 4.5 V to 5.5 V - ensures compatibility with standard 5-V logic rails and noise margin stability |
| VOH / VOL | ≥3.94 V / ≤0.36 V at IOL = 8 mA - guarantees clean logic-high and logic-low signaling into 50-Ω loads |
| Output Drive | ±8 mA - sufficient to drive multiple TTL/CMOS inputs or short PCB traces without signal degradation |
| Propagation Delay | 6.0 ns typical (CL = 50 pF) - supports >100 MHz bus toggle rates in point-to-point configurations |
| ESD Rating | ±2000 V HBM - meets industrial handling requirements without external protection diodes |
| Operating Temp | –40°C to +125°C - qualified for extended-temperature industrial and automotive under-hood applications |
| Power Dissipation | 12 pF Cpd - limits dynamic power consumption during high-frequency switching in dense logic arrays |
Pinout & Package
SN74AHCT540DBR is housed in a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, body size 7.2 mm × 5.3 mm, and total footprint 7.2 mm × 7.8 mm. This compact surface-mount package supports automated assembly and thermal performance with RθJA = 70°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | OE1, OE2 | Active-low output enables - independently control Y1–Y4 (OE1) and Y5–Y8 (OE2); tie high to disable group |
| 2–9 | A1–A8 | Noninverting data inputs - accept TTL-compatible signals (0.8 V/2.0 V thresholds) directly from microcontrollers or FPGAs |
| 11–18 | Y1–Y8 | 3-state buffered outputs - present high-impedance state when OE is high, eliminating bus contention |
| 10 | GND | Ground reference - must be connected to system ground plane for stable noise immunity and switching behavior |
| 20 | VCC | Positive supply - requires local 0.1 µF ceramic bypass capacitor placed within 3 mm of pin for transient suppression |
Key Features
| Feature | Design Value |
|---|---|
| TTL-compatible inputs | Accepts 0.8 V/2.0 V logic thresholds without level-shifting, simplifying interface with legacy microcontrollers and ASICs |
| Dual 3-state control | Independent OE1/OE2 pins allow partitioned bus management - e.g., isolate memory address vs. data lanes |
| Latch-up immunity | Exceeds 250 mA per JESD17 - prevents destructive latch-up during voltage transients or hot-plug events |
| Low dynamic power | 12 pF power dissipation capacitance minimizes switching current in high-frequency bus applications |
| Industrial temperature range | –40°C to +125°C operation enables use in motor drives, PLCs, and industrial gateways without derating |
Applications
| Memory Address Buffering | Microcontroller Bus Expansion |
|---|---|
Use Scenario: Driving 8-bit address lines from an MCU to external SRAM or flash memory with minimal skew and fanout loading. IC Role / Device Role / Timing Role: Noninverting buffer with 3-state outputs isolates MCU address bus during memory read/write cycles. Use Value: Enables clean address latching with tPLH ≤ 6.0 ns and eliminates contention when memory is deselected via OE control. | Use Scenario: Expanding GPIO count on an ARM Cortex-M4 by adding parallel I/O ports via 8-bit data bus interfacing. IC Role / Device Role / Timing Role: Bidirectional bus driver that buffers and isolates peripheral data lines using OE-controlled 3-state outputs. Use Value: Supports simultaneous read/write operations with <9 ns enable/disable timing, reducing bus arbitration overhead. |
| Industrial Sensor Hub Interface | Legacy System Logic Translation |
Use Scenario: Aggregating digital sensor outputs (e.g., 8-channel temperature or pressure sensors) onto a shared SPI or parallel diagnostic bus. IC Role / Device Role / Timing Role: Signal conditioner and bus driver that translates sensor logic levels to robust 5-V CMOS-compatible signals. Use Value: Delivers ±8 mA drive strength and ±2000 V HBM ESD protection, ensuring reliability in noisy factory-floor environments. | Use Scenario: Interfacing modern 3.3-V FPGA I/O banks with legacy 5-V peripheral logic (e.g., ISA-bus peripherals or discrete glue logic). IC Role / Device Role / Timing Role: Level-tolerant buffer that accepts TTL inputs while sourcing/sinking full 5-V CMOS currents. Use Value: Eliminates need for external level shifters due to native 0.8 V/2.0 V input thresholds and 5-V rail compatibility. |
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 |
|---|---|---|---|
| SN74AHCT240DBR | Inverting outputs (Y = A̅), same pinout and electrical specs - requires logic inversion in firmware or upstream logic | Suitable where inverted bus control is acceptable (e.g., active-low enable schemes) | Select SN74AHCT240DBR only if system design accommodates inverted data paths; otherwise retain SN74AHCT540DBR for direct signal pass-through. |
| 74LVC244APW,118 | 3.3-V only (1.65–3.6 V), lower drive (±24 mA), different pinout - not pin-compatible and requires level translation for 5-V systems | Targeted for low-voltage portable or battery-powered designs, not 5-V industrial buses | Choose 74LVC244APW,118 only in new 3.3-V designs; SN74AHCT540DBR remains optimal for existing 5-V infrastructure. |
Compared with SN74AHCT240DBR and 74LVC244APW,118, the SN74AHCT540DBR uniquely delivers noninverting 5-V bus buffering with dual OE control and industrial temperature support - making it the preferred choice for legacy-compatible, noise-immune, and thermally demanding applications.
Availability
SN74AHCT540DBR is available at Aetrix Electronics and suitable for industrial automation, embedded control, and test equipment requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant SSOP packaging.
Supply support for SN74AHCT540DBR 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 50 years of innovation in industrial, automotive, and communications markets.
The SN74AHCT540DBR belongs to TI's AHCT logic family - engineered for 5-V TTL-compatible interfacing with enhanced speed, noise immunity, and latch-up resistance in industrial control and instrumentation systems.
FAQ
What is the maximum operating temperature for the SN74AHCT540DBR?
The SN74AHCT540DBR is rated for continuous operation from –40°C to +125°C ambient temperature. This extended industrial temperature range is validated per TI's qualification standards and supports deployment in motor drives, programmable logic controllers, and outdoor industrial gateways without thermal derating. The SN74AHCT540DBR maintains full electrical specifications across this range, including VOH ≥ 3.8 V and tPLH ≤ 7.5 ns at 125°C.
Does the SN74AHCT540DBR require external pull-up resistors on its OE pins?
Yes - to ensure defined high-impedance state during power-up or power-down, OE1 and OE2 should each be tied to VCC through a pull-up resistor. TI recommends a value between 4.7 kΩ and 10 kΩ, selected based on the current-sinking capability of the driving source and required rise time. The SN74AHCT540DBR itself does not integrate internal pull-ups, so external biasing is mandatory for robust system initialization.
Can the SN74AHCT540DBR drive a 50-pF load with guaranteed timing?
Yes - the SN74AHCT540DBR specifies switching characteristics explicitly for CL = 50 pF, including tPLH/tPHL ≤ 10 ns (max) and tPZH/tPLZ ≤ 12 ns (max) across –40°C to 125°C. These values are production-tested and guaranteed, confirming reliable operation into typical PCB trace + connector + receiver input capacitance loads encountered in industrial backplanes and modular I/O systems.
Is the SN74AHCT540DBR pin-compatible with other packages in the AHCT540 family?
No - while all AHCT540 variants share identical logic functionality and pin numbering, the SN74AHCT540DBR (SSOP-20) has different mechanical dimensions, lead pitch (0.65 mm), and thermal characteristics than PDIP (N), SOIC (DW), or TVSOP (DGV) versions. PCB layout must be redesigned for each package; however, schematic symbol and net connectivity remain identical across the family.
What is the recommended bypass capacitor for the SN74AHCT540DBR VCC pin?
Texas Instruments specifies a 0.1 µF ceramic capacitor placed within 3 mm of the VCC pin (pin 20) and GND (pin 10) for the SN74AHCT540DBR. This value is optimized for high-frequency noise suppression up to ~100 MHz. For systems with multiple SN74AHCT540DBR devices or mixed-signal noise concerns, paralleling a 1 µF tantalum or X7R MLCC improves low-frequency decoupling - but the 0.1 µF local cap remains mandatory per TI's layout guidelines.
SN74AHCT540DBR 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:
- 1
- Number of Bits per Element:
- 8
- 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
SN74AHCT540DBR FAQ
1.How can I place an order for SN74AHCT540DBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT540DBR 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 SN74AHCT540DBR reliable?
The price and inventory of SN74AHCT540DBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT540DBR is usually 5 days.
3.What payment methods are accepted for SN74AHCT540DBR?
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SN74AHCT540DBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT540DBR 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 SN74AHCT540DBR?
For technical support, including SN74AHCT540DBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT540DBR requirements.
6.How does Aetrix verify that SN74AHCT540DBR is sourced from the original manufacturer or authorized distributors?
All SN74AHCT540DBR 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 SN74AHCT540DBR meets industry standards.
7.What is the process for return or replacement of SN74AHCT540DBR?
All SN74AHCT540DBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT540DBR, 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 SN74AHCT540DBR part is unused and in its original packaging.
Return procedure for SN74AHCT540DBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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