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Texas Instruments SN74BCT540AN
- Part No.:
- SN74BCT540AN
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74BCT540AN.pdf
- Description:
- IC BUFFER INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,600
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Product details
Overview
SN74BCT540AN 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 dual active-low 3-state enable inputs (OE1, OE2), and delivers ±64 mA output drive capability per channel at VCC = 4.5 V.
For engineers reviewing the SN74BCT540AN datasheet, SN74BCT540AN pinout, SN74BCT540AN application, or SN74BCT540AN equivalent, key selection criteria include its BiCMOS architecture for low ICCZ standby current (3–6 mA), data flow-through pinout for PCB layout optimization, and compatibility with legacy TTL bus systems requiring high sink/source drive and robust ESD protection (2000-V HBM).
Technical Context
This device implements eight independent non-inverting buffers, each with a dedicated input (A1–A8) and output (Y1–Y8), controlled by two shared 2-input AND gates (OE1, OE2) that force all corresponding outputs into high-impedance when either enable is high. The P-N-P input structure reduces DC loading on upstream logic.
Its BiCMOS design merges bipolar switching speed with CMOS low-power quiescent behavior, achieving tPLH/tPHL propagation delays as low as 1.9 ns (min) and tPZH/tPZL enable/disable times under 3.3 ns (min), while maintaining TTL-level input thresholds (VIH = 2 V, VIL = 0.8 V) and output voltage compliance (VOH ≥ 2.4 V, VOL ≤ 0.55 V at IOL = 64 mA).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures stable operation across industrial-grade 5-V rail tolerances. |
| Output Drive (IOL) | 64 mA per channel - Sufficient to drive 50-pF bus loads with fast edge rates and minimal voltage droop. |
| Propagation Delay (tPLH) | 2.0 ns (min) at VCC = 4.5 V - Enables high-speed address/data buffering in memory subsystems. |
| ICCZ Quiescent Current | 3–6 mA - Significantly lower than bipolar-only equivalents, reducing system power in idle states. |
| ESD Protection | 2000-V HBM - Meets JEDEC JESD22-A114A, supporting robust handling in manufacturing and field environments. |
| Input Clamp Current | –18 mA - Allows safe overvoltage transient suppression without external clamping diodes. |
| Operating Temperature | 0°C to 70°C - Qualified for commercial-grade embedded and computing applications. |
Pinout & Package
SN74BCT540AN is housed in a 20-pin plastic dual in-line package (PDIP-N), with 3.97 mm pitch, 13.97 mm body width, and 506 mm tube length. Its data flow-through layout places all eight inputs (A1–A8) on the left side and all eight outputs (Y1–Y8) on the right side, simplifying layer routing on double-sided PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A1–A8 Inputs | Non-inverting data inputs; P-N-P structure minimizes DC loading on preceding TTL or CMOS drivers. |
| 9 | GND | Power ground reference for all internal circuitry and output stage return path. |
| 10 | VCC | Positive supply rail (4.5–5.5 V); decoupling capacitor placement near this pin is critical for noise immunity. |
| 11, 19 | OE1, OE2 | Active-low 3-state enables; OR'd internally-either high forces all Y1–Y8 into high-Z state. |
| 12, 13, 14, 15, 16, 17, 18, 20 | Y1–Y8 Outputs | Buffered, totem-pole outputs capable of sinking 64 mA or sourcing 15 mA; compatible with 50-Ω transmission lines. |
Key Features
| Feature | Design Value |
|---|---|
| BiCMOS Process Technology | Combines bipolar speed and CMOS low ICCZ, enabling <6 mA standby current without sacrificing 2 ns propagation performance. |
| Data Flow-Through Pinout | Inputs (pins 1–8) and outputs (pins 12–20) on opposite sides reduce trace crossovers and improve signal integrity in dense bus layouts. |
| Dual 3-State Enable Logic | OE1/OE2 form a wired-OR interface-any one high disables all eight outputs, simplifying bus arbitration control logic. |
| TTL-Compatible Input Thresholds | VIH = 2.0 V, VIL = 0.8 V ensures reliable interfacing with standard 74LS/74ALS and microcontroller GPIOs without level shifting. |
| High Sink Current Capability | 64 mA per output supports direct connection to terminated 50-Ω buses or multiple TTL inputs without external drivers. |
Applications
| Memory Address Buffering | Parallel Bus Isolation |
|---|---|
|
Use Scenario: Driving 16-bit address lines from a microprocessor to multiple SRAM or EPROM chips on a shared memory bus. IC Role / Device Role / Timing Role: Non-inverting octal buffer providing fanout and drive strength; enables clean address transitions during memory read/write cycles. Use Value: Eliminates address skew and ground bounce via matched propagation delay (±0.5 ns typical) and low-output impedance (<10 Ω in low state). |
Use Scenario: Isolating a CPU data bus from peripheral devices (e.g., UART, ADC, DAC) during inactive periods to prevent contention. IC Role / Device Role / Timing Role: 3-state bus driver controlled by CPU address decoder outputs; asserts high-Z when peripheral is deselected. Use Value: Prevents bus conflicts with <3.3 ns disable time (tPLZ), ensuring glitch-free transitions between active and isolated states. |
| Legacy System Bus Expansion | TTL-Level Signal Translation |
|
Use Scenario: Extending a vintage 8-bit computer's expansion bus to support additional I/O cards while maintaining timing margins. IC Role / Device Role / Timing Role: Octal buffer replicating address/data signals with TTL-compatible voltage levels and drive strength. Use Value: Maintains setup/hold timing integrity with tPHL = 0.3 ns (min), allowing reliable operation up to 100 MHz effective bus clocking. |
Use Scenario: Interfacing modern low-voltage microcontrollers (3.3 V GPIO) to legacy 5-V TTL peripherals requiring higher input current. IC Role / Device Role / Timing Role: Level-shifting buffer leveraging P-N-P inputs to accept 3.3 V logic while sourcing/sinking full TTL currents. Use Value: Avoids external pull-up resistors or discrete transistor stages-direct connection enabled by VIH = 2.0 V and IIL = –0.6 mA. |
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 process; higher ICCZ (40 mA), slower tPLH (15 ns min), no BiCMOS power savings. | Limited to lower-speed systems (<20 MHz); unsuitable where thermal dissipation or standby current matters. | Choose only if strict LS-TTL compatibility is required and power/thermal budget allows. |
| SN74ACT540N | Advanced CMOS; wider VCC range (4.5–5.5 V), lower ICCZ (2 µA), but reduced IOL (24 mA) and no P-N-P inputs. | Cannot drive heavy TTL loads directly; requires series termination or external drivers for bus applications. | Select when ultra-low power is critical and load capacitance is ≤30 pF-avoid for legacy bus buffering. |
Compared with SN74LS240N, SN74BCT540AN delivers 7× faster propagation and 13× lower standby current; compared with SN74ACT540N, it provides 2.7× higher sink drive and native TTL input compatibility-making it uniquely suited for legacy bus expansion where both speed and drive strength are mandatory.
Availability
SN74BCT540AN is available at Aetrix Electronics and suitable for memory subsystem design, parallel bus isolation, legacy system upgrades, and TTL-level signal translation requiring stable component supply and long-term industrial availability.
Supply support for SN74BCT540AN 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 founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
SN74BCT540AN belongs to TI's BCT (Bipolar-CMOS Transistor) logic family, engineered specifically to bridge performance gaps between standard TTL and advanced CMOS-delivering high-speed bus driving with low-power quiescent behavior for legacy-compatible digital systems.
FAQ
What is the maximum output sink current specification for SN74BCT540AN?
The SN74BCT540AN is rated for 64 mA per output in the low state (IOL) at VCC = 4.5 V and TA = 25°C, as specified in the electrical characteristics table. This value ensures reliable driving of multiple TTL inputs or 50-Ω terminated bus lines without exceeding VOL limits (≤0.55 V). Derating applies at elevated temperatures or lower supply voltages.
Does SN74BCT540AN support hot-swap or live-insertion applications?
SN74BCT540AN does not include explicit hot-swap protection features such as power-on reset, slew-rate control, or back-drive immunity. Its absolute maximum ratings allow VO = –0.5 V to 5.5 V in disabled state, but uncontrolled power sequencing may cause latch-up or excessive ICCZ. For live-insertion, external current-limiting and sequencing circuitry is required.
Can SN74BCT540AN be used with 3.3-V logic inputs?
Yes-SN74BCT540AN accepts 3.3-V logic-high inputs reliably because its VIH threshold is 2.0 V (min), well below 3.3 V. However, its outputs swing to 5-V TTL levels, so interfacing to 3.3-V receivers requires external level-shifting or clamping to avoid overvoltage damage.
What is the recommended pull-up resistor value for OE pins during power-up?
Texas Instruments recommends tying OE1 and OE2 to VCC through a pull-up resistor to ensure high-impedance outputs at power-up. The minimum resistance is determined by the driver's current-sinking capability: for SN74BCT540AN, a 4.7-kΩ resistor is typical, limiting current to <1 mA while guaranteeing OE remains below 0.8 V during assertion.
Is SN74BCT540AN RoHS compliant?
Yes-SN74BCT540AN carries NIPDAU (nickel/palladium/gold) lead finish and is RoHS compliant per TI's packaging addendum. It meets EU Directive 2011/65/EU requirements, with no lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE above threshold limits.
SN74BCT540AN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74BCT
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- 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:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74BCT540AN FAQ
1.How can I place an order for SN74BCT540AN through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74BCT540AN 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 SN74BCT540AN reliable?
The price and inventory of SN74BCT540AN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT540AN is usually 5 days.
3.What payment methods are accepted for SN74BCT540AN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74BCT540AN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74BCT540AN?
SN74BCT540AN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74BCT540AN 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 SN74BCT540AN?
For technical support, including SN74BCT540AN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT540AN requirements.
6.How does Aetrix verify that SN74BCT540AN is sourced from the original manufacturer or authorized distributors?
All SN74BCT540AN 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 SN74BCT540AN meets industry standards.
7.What is the process for return or replacement of SN74BCT540AN?
All SN74BCT540AN units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT540AN, 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 SN74BCT540AN part is unused and in its original packaging.
Return procedure for SN74BCT540AN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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