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Texas Instruments SN74AHC540NSR
- Part No.:
- SN74AHC540NSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHC540NSR.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,994
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Product details
Overview
SN74AHC540NSR from Texas Instruments is an octal inverting buffer/driver with 3-state outputs, designed for bus line driving and memory address register buffering in 2-V to 5.5-V systems. It features dual active-low output-enable inputs (OE1, OE2), inverted output logic, and ±25 mA output drive capability at 5 V. Used in industrial control backplanes and legacy data bus interfaces.
For engineers reviewing the SN74AHC540NSR datasheet, SN74AHC540NSR pinout, SN74AHC540NSR application, or SN74AHC540NSR equivalent, key selection criteria include 3-state timing (tPZH ≤ 12.5 ns at 5 V), latch-up immunity (>250 mA per JESD 17), and SOP-20 package thermal resistance (60°C/W).
Technical Context
The SN74AHC540NSR implements eight independent inverting buffer channels, each with a two-input AND gate control structure for 3-state enable-OE1 and OE2 must both be low to activate outputs. Its AHC logic family ensures CMOS-level power efficiency with TTL-compatible thresholds across 2–5.5 V operation.
Input transition rate limits are specified (20 ns/V at 5 V), and unused inputs require termination to VCC or GND per SCBA004. The device supports hot-insertion via controlled 3-state entry/exit timing and exhibits robust noise margins (VIL(D) = 1.5 V, VIH(D) = 3.5 V at 5 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2 V to 5.5 V - supports mixed-voltage system interfacing and brown-out tolerant operation |
| Output Drive | ±8 mA at 5 V - sufficient to drive 50-pF loads with <8 ns propagation delay (tPLH/tPHL) |
| 3-State Enable Delay | tPZH/tPLZ ≤ 10.5 ns at 5 V - enables fast bus arbitration and multiplexing in time-critical control paths |
| Input Thresholds | VIH = 3.85 V, VIL = 1.65 V at VCC = 5.5 V - provides 0.9 V noise margin against TTL-level interference |
| Quiescent Current | ICC ≤ 40 µA at 5.5 V - enables low-static-power operation in battery-backed or standby subsystems |
| Thermal Resistance | θJA = 60°C/W (NS package) - allows sustained 8-channel switching at ambient up to 85°C without derating |
| Latch-Up Immunity | >250 mA per JESD 17 - prevents destructive current runaway during transient overvoltage events |
Pinout & Package
SOP-20 (Small Outline Package, 20-pin, 0.300-inch body width, gull-wing leads). Pin 1 index marked; pins 1–10 on top row left-to-right, pins 11–20 on bottom row right-to-left (standard NS package orientation).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OE1) | Active-low output enable 1 | ANDed with OE2; high forces all Y outputs into high-Z regardless of A inputs |
| 2–9 (A1–A8) | Inverting input terminals | Each drives corresponding inverted output Y1–Y8 when both OE1/OE2 are low |
| 10 (GND) | Ground reference | Return path for all internal logic and output current; requires low-impedance PCB plane |
| 11 (VCC) | Supply voltage | Power rail for logic core and output drivers; bypass capacitor (0.1 µF) required at pin |
| 12 (OE2) | Active-low output enable 2 | Second input to 2-input AND gate controlling 3-state; enables redundant enable signaling |
| 13–20 (Y1–Y8) | Inverting 3-state outputs | Drive external bus lines; high-Z state isolates connected devices during contention or idle |
Key Features
| Feature | Design Value |
|---|---|
| Inverting 3-state architecture | Enables bidirectional bus sharing without external direction control logic |
| Dual active-low OE inputs | Supports OR-ed enable trees or fault-safety redundancy (both OE must be asserted) |
| High noise immunity | Dynamic input thresholds (VIH(D)/VIL(D)) ensure reliable operation in electrically noisy industrial environments |
| Bus-hold circuitry absent | Requires explicit input termination - avoids unintended floating-node behavior in un-driven states |
| CMOS input characteristics | Input leakage ≤ ±1 µA - eliminates need for pull-up/down resistors except at power-up/down sequencing |
Applications
| Industrial Backplane Interface | Legacy Memory Address Buffering |
|---|---|
|
Use Scenario: Isolating microcontroller address bus from multiple peripheral decoders in modular PLC racks. IC Role / Device Role / Timing Role: Inverting 3-state buffer providing address signal integrity and contention-free bus access during module hot-swap. Use Value: Dual OE inputs allow synchronized enable/disable across rack slots; tPZH ≤ 10.5 ns ensures setup compliance with 25-MHz address strobes. |
Use Scenario: Driving Z80 or 8086 CPU address lines to static RAM and I/O port chips in retro-computing hardware. IC Role / Device Role / Timing Role: Level-shifting and fanout expansion buffer with inverted logic matching original system timing maps. Use Value: 2-V to 5.5-V operation supports mixed 3.3 V/5 V board designs; ±8 mA drive sustains signal integrity across 6-inch traces. |
| Programmable Logic Glue Logic | Test Equipment Signal Conditioning |
|
Use Scenario: Interfacing FPGA I/O banks to legacy TTL peripherals in automated test fixtures. IC Role / Device Role / Timing Role: Voltage-level translator and bus isolator between configurable logic and fixed-function devices. Use Value: Guaranteed 3-state timing (tPLZ ≤ 10.5 ns) enables deterministic bus release before FPGA reconfiguration cycles. |
Use Scenario: Conditioning parallel status signals from analog measurement modules before digitization in benchtop DMMs. IC Role / Device Role / Timing Role: Noise-filtered signal repeater with controlled edge rates to reduce crosstalk in dense signal routing. Use Value: Input transition rate limit (20 ns/V at 5 V) suppresses EMI from fast-switching sources; latch-up immunity protects against probe-induced transients. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AHCT540NSR | Higher VIH/VIL thresholds (2 V/0.8 V at 5 V) for TTL-input compatibility; otherwise identical pinout and timing | Better suited for mixed 5 V TTL/CMOS systems where input noise immunity is secondary to legacy logic matching | Select SN74AHCT540NSR only if interfacing directly to standard TTL outputs; SN74AHC540NSR preferred for pure CMOS or low-power domains |
| 74LCX540MTCX | Lower VCC range (2.0–3.6 V), higher speed (tPLH ≤ 5.2 ns at 3.3 V), different pinout (TSSOP-20 vs SOP-20) | Optimized for 3.3 V-only portable/embedded systems; not drop-in compatible due to pin assignment mismatch | Choose 74LCX540MTCX only for new 3.3 V designs requiring sub-6 ns propagation; SN74AHC540NSR remains optimal for 5 V or dual-voltage buses |
Compared with SN74AHCT540NSR and 74LCX540MTCX, the SN74AHC540NSR uniquely balances wide supply range (2–5.5 V), industry-standard SOP-20 footprint, and guaranteed 3-state timing for bus arbitration-making it the default choice for industrial backplane and legacy upgrade applications where voltage flexibility and layout continuity are critical.
Availability
SN74AHC540NSR is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy memory subsystems, programmable logic glue logic, and test equipment signal conditioning requiring stable component supply and long-term obsolescence management.
Supply support for SN74AHC540NSR 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 industrial-grade interface ICs.
The SN74AHC540NSR belongs to TI's AHC logic family-designed specifically for high-speed, low-power, 3-state bus interface applications in industrial automation, instrumentation, and computing infrastructure.
FAQ
What is the recommended power-up sequence for SN74AHC540NSR to avoid bus contention?
TI recommends tying OE1 and OE2 to VCC through pullup resistors (minimum value determined by driver sink capability) during power-up and power-down. This ensures all outputs remain in high-impedance until VCC stabilizes and system firmware asserts valid enable signals. For SN74AHC540NSR, this prevents unintended drive conflicts on shared buses before controller initialization completes.
Does SN74AHC540NSR include bus-hold or Schmitt-trigger inputs?
No, SN74AHC540NSR does not integrate bus-hold or Schmitt-trigger circuitry. All inputs require explicit DC termination to VCC or GND to prevent floating nodes and undefined logic states. This design choice preserves signal integrity in controlled environments but mandates external biasing per TI application note SCBA004.
Can SN74AHC540NSR drive a 50-pF load at 5 V while meeting tPLH/tPHL specifications?
Yes, SN74AHC540NSR guarantees tPLH and tPHL ≤ 8 ns at VCC = 5 V with CL = 50 pF, as confirmed in the switching characteristics table (SCLS260J, page 4). This makes SN74AHC540NSR suitable for driving moderate-capacitance backplane traces or multiple CMOS inputs without timing violation.
What is the maximum continuous output current rating for SN74AHC540NSR?
The absolute maximum continuous output current for SN74AHC540NSR is ±25 mA per output, as specified under "Absolute Maximum Ratings." At recommended operating conditions (VCC = 5 V), the device delivers ±8 mA while maintaining VOH ≥ 3.94 V and VOL ≤ 0.44 V-ensuring robust logic-level compliance under typical load conditions.
Is SN74AHC540NSR compliant with JEDEC MO-150 package standards?
Yes, the SN74AHC540NSR uses the SOP-20 (NS) package, which conforms to JEDEC MO-150 mechanical standard per TI's MTSS001C documentation. This ensures compatibility with standard surface-mount assembly processes, reflow profiles, and automated optical inspection systems used in high-reliability manufacturing.
SN74AHC540NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHC
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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:
- 2V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74AHC540NSR FAQ
1.How can I place an order for SN74AHC540NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHC540NSR 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 SN74AHC540NSR reliable?
The price and inventory of SN74AHC540NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHC540NSR is usually 5 days.
3.What payment methods are accepted for SN74AHC540NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHC540NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHC540NSR?
SN74AHC540NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHC540NSR 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 SN74AHC540NSR?
For technical support, including SN74AHC540NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHC540NSR requirements.
6.How does Aetrix verify that SN74AHC540NSR is sourced from the original manufacturer or authorized distributors?
All SN74AHC540NSR 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 SN74AHC540NSR meets industry standards.
7.What is the process for return or replacement of SN74AHC540NSR?
All SN74AHC540NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHC540NSR, 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 SN74AHC540NSR part is unused and in its original packaging.
Return procedure for SN74AHC540NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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