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Texas Instruments SN74HC540PWR
- Part No.:
- SN74HC540PWR
- Manufacturer:
- Texas Instruments
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74HC540PWR.pdf
- Description:
- IC BUFFER INVERT 6V 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,110
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Product details
Overview
SN74HC540PWR from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for bus interface and data routing in digital systems. It operates from 2 V to 6 V, delivers ±6 mA output drive at 5 V, exhibits typical propagation delay of 8 ns (VCC = 4.5 V, CL = 50 pF), and features low ICC of 80 μA max - enabling use in low-power industrial control and embedded I/O expansion.
For engineers reviewing the SN74HC540PWR datasheet, SN74HC540PWR pinout, SN74HC540PWR application, or SN74HC540PWR equivalent, key selection considerations include its inverted 3-state logic architecture, TSSOP-20 package footprint, dual OE-controlled high-impedance output enable, and compatibility with LSTTL loads in space-constrained PCB layouts.
Technical Context
The SN74HC540PWR implements eight independent inverting buffers, each with complementary input-to-output polarity. Its 2-input NOR-based 3-state control allows either OE1 or OE2 high to place all outputs in high-impedance mode - supporting bidirectional bus arbitration without external logic.
It uses silicon-gate CMOS technology for TTL-compatible input thresholds and rail-to-rail output swing. The data flow-through pinout (inputs on one side, outputs on the opposite) minimizes trace crosstalk and simplifies layer routing in dense 2-layer PCB designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2 V to 6 V - supports mixed-voltage system interfacing (e.g., 3.3 V MCU to 5 V peripheral bus) |
| Output Drive | ±6 mA at 5 V - directly drives up to 15 LSTTL loads without external pull-ups |
| Propagation Delay | 8 ns typical (VCC = 4.5 V, CL = 50 pF) - enables reliable operation in ≤25 MHz bus cycles |
| Quiescent Current | 80 μA max - reduces standby power in battery-backed or energy-harvesting nodes |
| Input Leakage | 1 μA max - ensures stable logic levels with high-impedance source interfaces |
| 3-State Enable Time | 32 ns max (VCC = 6 V, CL = 50 pF) - meets tight timing windows in fast bus turnaround protocols |
| Operating Temperature | –40 °C to +85 °C - qualified for industrial-grade embedded applications |
Pinout & Package
TSSOP-20 package (6.5 mm × 4.4 mm, 1.2 mm max height), lead finish NIPDAU, moisture sensitivity level 1 (260 °C peak reflow), RoHS compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | Buffer Inputs (A1–A8) | Active-high logic inputs driving inverted outputs; require explicit VCC/GND tie-off if unused |
| 9, 10, 11, 12, 13, 14, 15, 16 | Buffer Outputs (Y1–Y8) | Inverted, 3-state outputs; high-impedance when OE1 or OE2 = high |
| 17, 19 | Output Enable Inputs (OE1, OE2) | NOR logic: either high forces all Yn into high-Z - enables flexible bus arbitration control |
| 18 | GND | Ground reference for logic and output stages; requires local 0.1-μF bypass capacitor |
| 20 | VCC | Power supply (2–6 V); must be decoupled adjacent to pin with 0.1-μF ceramic capacitor |
Key Features
| Feature | Design Value |
|---|---|
| Data flow-through pinout | Inputs (pins 1–8) and outputs (pins 9–16) on opposite sides - eliminates layer jumps and reduces crosstalk in compact layouts |
| Inverting 3-state logic | Each buffer inverts input signal while supporting high-impedance state - simplifies bus direction control in half-duplex interfaces |
| Dual OE control with NOR gating | Independent OE1/OE2 pins allow hardware-selectable enable paths - supports redundant or multi-master bus schemes |
| Low dynamic power consumption | 35 pF typical power dissipation capacitance per buffer - minimizes switching current in high-frequency address/data buses |
| TTL-compatible input thresholds | VIH = 3.15 V, VIL = 1.35 V at VCC = 4.5 V - ensures robust noise margin when interfacing with legacy 5 V logic |
Applications
| Industrial PLC I/O Expansion | Embedded Microcontroller Bus Interface |
|---|---|
Use Scenario: Adding isolated digital input/output capability to a programmable logic controller via backplane or ribbon cable. IC Role / Device Role / Timing Role: Inverting buffer isolates MCU GPIO from noisy field-side signals while enabling 3-state sharing of common data bus lines. Use Value: ±6 mA drive strength sustains signal integrity across 30 cm ribbon cables; 8 ns tpd supports 25 MHz scan rates without timing violations. | Use Scenario: Interfacing an ARM Cortex-M4 microcontroller (3.3 V I/O) to legacy 5 V peripherals such as LCD controllers or EEPROMs. IC Role / Device Role / Timing Role: Level-shifting buffer with 3-state control manages bidirectional data flow between mismatched voltage domains. Use Value: Wide 2–6 V supply range allows direct 3.3 V or 5 V operation; inverted logic matches standard address latch conventions in memory-mapped peripherals. |
| Test Equipment Signal Conditioning | Automated Test Fixture Control |
Use Scenario: Driving multiple DUT (device under test) enable lines simultaneously from a single FPGA I/O bank. IC Role / Device Role / Timing Role: Octal buffer consolidates FPGA pin count while providing synchronized, slew-rate-controlled output transitions. Use Value: Matched propagation delays (<1 ns skew across all 8 channels) ensure deterministic timing alignment across parallel test vectors. | Use Scenario: Controlling relay drivers and LED indicators in production-line functional testers where board space is constrained. IC Role / Device Role / Timing Role: Compact TSSOP-20 buffer provides high-density I/O buffering with minimal PCB area and thermal footprint. Use Value: 6.5 mm × 4.4 mm footprint saves >40% board area vs. SOIC-20; 1.2 mm height enables stacking in multi-board fixtures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT540PW | CMOS input with TTL-compatible thresholds (VIH = 2 V min), higher ICC (4 μA typ), identical pinout and function | Better noise immunity in noisy industrial environments due to tighter input threshold specs | Choose SN74HCT540PW when interfacing with legacy 5 V TTL sources where VIH/VIL margins are marginal |
| 74LCX540MTCX | Lower VCC range (2.0–3.6 V), 3.3 V optimized, 5 V tolerant inputs, smaller TSSOP-20 (4.4 mm × 3.5 mm) | Designed for modern low-voltage systems; not suitable for 5 V-only buses | Choose 74LCX540MTCX only in 3.3 V domains requiring 5 V-tolerant inputs and minimal board area |
Compared with SN74HC540PWR, SN74HCT540PW offers superior noise rejection in electrically harsh settings but draws more quiescent current, while 74LCX540MTCX reduces footprint and power in 3.3 V systems but sacrifices 5 V bus compatibility.
Availability
SN74HC540PWR is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, embedded microcontroller bus interface, and automated test fixture control requiring stable component supply and long-term manufacturability.
Supply support for SN74HC540PWR 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 for industrial, automotive, and communications markets.
The SN74HC540PWR belongs to TI's 74HC logic family - engineered for high-speed, low-power, pin-compatible replacements of legacy TTL devices in space- and power-sensitive digital interfaces.
FAQ
What is the maximum clock frequency supported by SN74HC540PWR in a data bus application?
The SN74HC540PWR does not operate on a clock signal - it is a combinatorial buffer with propagation delay (tpd) of 8 ns typical at 4.5 V and 50 pF load. This supports reliable data transfer in asynchronous bus systems up to approximately 25 MHz (1/tpd), assuming setup/hold timing margins are met by the driving and receiving devices. For synchronous protocols, system-level timing analysis must include trace delays and receiver specifications alongside SN74HC540PWR's tpd.
Can SN74HC540PWR drive LEDs directly without current-limiting resistors?
No, SN74HC540PWR must not drive LEDs directly without series current-limiting resistors. Its absolute maximum continuous output current is ±35 mA per pin, but recommended operating conditions specify ±6 mA at 5 V. Exceeding this risks exceeding junction temperature limits and degrading long-term reliability. Always use a resistor sized to limit current to ≤6 mA (e.g., 680 Ω at 5 V) when using SN74HC540PWR to sink or source LED current.
Is SN74HC540PWR pin-compatible with SN74HC240N?
No, SN74HC540PWR is not pin-compatible with SN74HC240N. While both are octal buffers with 3-state outputs, SN74HC240N has non-inverting outputs and different pin assignments: its OE inputs are on pins 1 and 19, whereas SN74HC540PWR places OE1/OE2 on pins 17 and 19. Swapping them without circuit revision will invert logic states and misconfigure enable control - always verify pin functions against the specific device's datasheet before substitution.
Does SN74HC540PWR require external pull-up or pull-down resistors on unused inputs?
Yes, all unused inputs of SN74HC540PWR must be externally tied to VCC or GND. Floating CMOS inputs cause increased ICC, unpredictable output states, and potential device malfunction due to intermediate voltage levels triggering both NMOS and PMOS transistors. TI recommends connecting unused A1–A8 inputs to VCC or GND with short traces; OE1/OE2 should be grounded unless actively controlled, as either high disables all outputs.
What is the thermal resistance (RθJA) of SN74HC540PWR in its TSSOP-20 package?
The junction-to-ambient thermal resistance (RθJA) of SN74HC540PWR in the TSSOP-20 (PW) package is 131.8 °C/W, as specified in the July 2022 revision of the SCLS007F datasheet. This value assumes standard JEDEC 2-layer board conditions (1-inch² copper pad). Actual thermal performance improves with additional PCB copper area, internal planes, or thermal vias - design reviews should validate junction temperature (TJ = TA + (P × RθJA)) stays below 150 °C under worst-case load.
SN74HC540PWR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-TSSOP (0.173", 4.40mm 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:
- 7.8mA, 7.8mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP
SN74HC540PWR FAQ
1.How can I place an order for SN74HC540PWR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC540PWR 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 SN74HC540PWR reliable?
The price and inventory of SN74HC540PWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC540PWR is usually 5 days.
3.What payment methods are accepted for SN74HC540PWR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC540PWR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC540PWR?
SN74HC540PWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC540PWR 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 SN74HC540PWR?
For technical support, including SN74HC540PWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC540PWR requirements.
6.How does Aetrix verify that SN74HC540PWR is sourced from the original manufacturer or authorized distributors?
All SN74HC540PWR 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 SN74HC540PWR meets industry standards.
7.What is the process for return or replacement of SN74HC540PWR?
All SN74HC540PWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC540PWR, 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 SN74HC540PWR part is unused and in its original packaging.
Return procedure for SN74HC540PWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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