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Texas Instruments SN74BCT540ANSR
- Part No.:
- SN74BCT540ANSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74BCT540ANSR.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,680
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Product details
Overview
SN74BCT540ANSR from Texas Instruments is an octal buffer/driver with 3-state outputs, designed for bus line driving and memory address register buffering in 5-V TTL-compatible systems. It operates from 4.5 V to 5.5 V, features biCMOS technology for low ICCZ (3–6 mA), supports 64 mA low-level output current, and uses a dual active-low 3-state enable (OE1/OE2) architecture.
For engineers reviewing the SN74BCT540ANSR datasheet, SN74BCT540ANSR pinout, SN74BCT540ANSR application, or SN74BCT540ANSR equivalent, key selection criteria include its 20-pin SOP-NS package, data flow-through pinout (inputs on one side, outputs on the other), P-N-P input structure for reduced DC loading, and JESD22-compliant ESD protection (2000-V HBM).
Technical Context
This device implements two independent 4-bit 3-state buffers, each controlled by a dedicated active-low enable input (OE1, OE2). The 3-state control logic is a 2-input AND gate with inverted inputs - either OE high forces all eight corresponding outputs into high-impedance state.
Its biCMOS design integrates bipolar drivers with CMOS input stages, delivering TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2.0 V), fast switching (tPHL ≤ 4.0 ns, tPLH ≤ 6.9 ns at 5 V), and low quiescent current in 3-state mode (ICCZ ≤ 6 mA).
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 mixed-voltage logic systems. |
| Output Drive | 64 mA sink per output - sufficient to drive heavy capacitive bus loads without external buffering. |
| Propagation Delay | tPHL ≤ 4.0 ns, tPLH ≤ 6.9 ns (VCC = 4.5–5.5 V, CL = 50 pF) - enables high-speed address/data path timing in memory subsystems. |
| Input Structure | P-N-P input stage - reduces DC input loading, minimizing power supply current draw from upstream logic. |
| ESD Protection | 2000-V HBM, 200-V MM, 1000-V CDM - exceeds JEDEC JESD22 standards for robust board-level handling and assembly. |
| 3-State Enable Logic | Active-low dual OE (OE1, OE2) - allows independent control of two 4-bit groups, supporting flexible bus arbitration schemes. |
| Package | SOP-NS (20-pin) - surface-mount package with 0.65 mm pitch, optimized for automated PCB assembly and space-constrained layouts. |
Pinout & Package
SOP-NS package: 20-pin small-outline plastic package, 7.6 mm × 13.0 mm body, 0.65 mm lead pitch, 2.65 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A1–A8 (Inputs) | Non-inverting data inputs - accept TTL-level signals; P-N-P structure minimizes DC loading on source logic. |
| 9 | GND | Ground reference for all internal circuitry and output drivers. |
| 10 | VCC | Positive supply (4.5–5.5 V) - powers both input and output stages; decoupling near this pin is critical for noise immunity. |
| 11, 12 | OE1, OE2 | Active-low 3-state enables - each controls four outputs (OE1 → Y1–Y4, OE2 → Y5–Y8); tied to VCC via pull-up for power-up safety. |
| 13–20 | Y1–Y8 (Outputs) | 3-state totem-pole outputs - drive buses bidirectionally when enabled; high-Z state prevents contention during bus sharing. |
Key Features
| Feature | Design Value |
|---|---|
| Data Flow-Through Pinout | Inputs (pins 1–8) and outputs (pins 13–20) are on opposite sides - simplifies PCB routing, reduces crosstalk, and enables straight-through trace layout. |
| BiCMOS Architecture | Combines bipolar output drivers (for speed/current) with CMOS input stages (for low ICCZ) - achieves 3–6 mA ICCZ vs. >20 mA in legacy TTL. |
| Dual Independent 3-State Control | Separate OE1/OE2 pins allow partitioning of the octal bus into two 4-bit segments - supports interleaved memory addressing or multi-master arbitration. |
| TTL-Compatible Input Thresholds | VIH = 2.0 V min, VIL = 0.8 V max - ensures reliable interfacing with legacy 74LS/74ALS and modern 5-V microcontrollers without level shifters. |
| Low Capacitance I/O | Ci = 5 pF (input), Co = 10 pF (output) - minimizes signal degradation and timing skew on high-frequency parallel buses. |
Applications
| Memory Address Buffering | System Bus Driver |
|---|---|
Use Scenario: Buffering 8-bit address lines between a microcontroller and SRAM or EPROM in embedded control systems. IC Role / Device Role / Timing Role: Non-inverting octal buffer with 3-state outputs - isolates address bus during DMA cycles and enables clean signal integrity across 10+ cm traces. Use Value: Delivers 64 mA sink capability and sub-7 ns propagation delay to meet tight address setup/hold timing in 10–25 MHz memory interfaces. |
Use Scenario: Driving shared data/address bus in industrial PLC backplanes with multiple masters (CPU, DMA, peripheral controllers). IC Role / Device Role / Timing Role: Bidirectional bus driver with dual OE control - allows dynamic bus ownership handoff without contention or glitches. Use Value: Dual active-low OE inputs (OE1/OE2) enable independent gating of two 4-bit lanes, supporting split-bus protocols and reducing arbitration logic complexity. |
| Legacy TTL System Interface | Industrial I/O Expansion |
Use Scenario: Interfacing modern 5-V MCUs to legacy TTL-based peripheral cards (e.g., ISA-style add-on modules) requiring strict voltage and timing compliance. IC Role / Device Role / Timing Role: Level-shifting and fanout buffer - matches 74LS input thresholds while driving multiple TTL loads with minimal skew. Use Value: P-N-P input structure draws only 0.6 mA max input current, preventing excessive loading on MCU GPIOs or older TTL outputs. |
Use Scenario: Expanding parallel I/O on programmable logic controllers where field wiring connects to buffered address/data lines routed over long cable runs. IC Role / Device Role / Timing Role: Robust bus driver with ESD-hardened I/O - protects against induced transients in noisy factory environments. Use Value: 2000-V HBM ESD rating and 5.5-V absolute max output voltage tolerance ensure reliability in unshielded industrial enclosures with frequent operator contact. |
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 | Bipolar TTL design; higher ICCZ (25 mA), slower tPLH (15 ns), no biCMOS power savings. | Limited to lower-speed (< 10 MHz) legacy systems; lacks ESD hardening and flow-through pinout. | Choose only if drop-in replacement in existing LS-based designs is required and power/ESD are not constraints. |
| SN74LVC244APW | 3.3-V CMOS; 3.6-V max VCC; VIH/VIL scaled to 3.3 V; lower drive (24 mA), smaller SOP-20 package. | Requires level translation for 5-V systems; unsuitable for direct 5-V bus driving without interface logic. | Select for new 3.3-V designs prioritizing ultra-low ICC and smaller footprint; not a functional substitute in 5-V applications. |
Compared with SN74LS240N, SN74BCT540ANSR delivers 2× faster switching and 80% lower standby current; versus SN74LVC244APW, it provides native 5-V operation and 2.7× higher output drive - making it the only direct-fit solution for high-current, 5-V bus buffering with ESD resilience.
Availability
SN74BCT540ANSR is available at Aetrix Electronics and suitable for memory address buffering, system bus driving, and industrial I/O expansion requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for SN74BCT540ANSR 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 heritage in industry-standard logic families.
The SN74BCT540A belongs to TI's BCT (Bipolar-CMOS Transistor) logic series, engineered specifically for high-speed, low-power 5-V bus interface applications in industrial and computing systems.
FAQ
What is the recommended power-up sequence for SN74BCT540ANSR to avoid bus contention?
TI recommends tying both OE1 and OE2 to VCC through a pull-up resistor (value determined by driver sink capability) to ensure outputs remain in high-impedance state during power ramp-up. This prevents unintended bus driving before system initialization completes. The SN74BCT540ANSR datasheet specifies this as mandatory for safe power sequencing, especially in multi-driver bus configurations.
Does SN74BCT540ANSR support hot-swap or live-insertion applications?
No - SN74BCT540ANSR is not rated for hot-swap operation. Its absolute maximum ratings do not include powered insertion stress, and the 3-state enable logic lacks built-in slew-rate control or fault detection. For hot-swap use, TI recommends dedicated hot-swap controllers (e.g., TPS2375x) paired with isolated buffers, not the SN74BCT540ANSR.
Can SN74BCT540ANSR drive a 50-pF load at 25 MHz without signal integrity issues?
Yes - with tPHL ≤ 4.0 ns and tPLH ≤ 6.9 ns into 50 pF (per datasheet Figure 1 test conditions), the SN74BCT540ANSR maintains clean edges and meets setup/hold margins for 25-MHz clocked bus systems. Its 10-pF output capacitance and 64-mA drive strength ensure <1 ns rise/fall times under typical PCB trace loads.
What is the thermal resistance (θJA) of the SN74BCT540ANSR in its SOP-NS package?
The SN74BCT540ANSR in the SOP-NS (NS) package has a junction-to-ambient thermal resistance (θJA) of 60°C/W, as specified in the "Absolute Maximum Ratings" table of the SCBS012E datasheet. This value assumes standard JEDEC 2-layer board conditions and is critical for calculating maximum allowable power dissipation at elevated ambient temperatures.
Is SN74BCT540ANSR pin-compatible with SN74BCT540AN or SN74BCT540ADW?
Yes - SN74BCT540ANSR, SN74BCT540AN (PDIP), and SN74BCT540ADW (SOIC-DW) share identical 20-pin functional pinouts and electrical specifications. All three variants implement the same logic function, timing, and drive strength; only package type (SOP-NS vs. PDIP vs. SOIC-DW), marking, and packaging format differ.
SN74BCT540ANSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74BCT
- Package/Case:
- 20-SOIC (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:
- 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-SO
SN74BCT540ANSR FAQ
1.How can I place an order for SN74BCT540ANSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74BCT540ANSR 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 SN74BCT540ANSR reliable?
The price and inventory of SN74BCT540ANSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT540ANSR is usually 5 days.
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SN74BCT540ANSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74BCT540ANSR 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 SN74BCT540ANSR?
For technical support, including SN74BCT540ANSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT540ANSR requirements.
6.How does Aetrix verify that SN74BCT540ANSR is sourced from the original manufacturer or authorized distributors?
All SN74BCT540ANSR 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 SN74BCT540ANSR meets industry standards.
7.What is the process for return or replacement of SN74BCT540ANSR?
All SN74BCT540ANSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT540ANSR, 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 SN74BCT540ANSR part is unused and in its original packaging.
Return procedure for SN74BCT540ANSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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