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Texas Instruments SN74HC540PW
- Part No.:
- SN74HC540PW
- Manufacturer:
- Texas Instruments
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74HC540PW.pdf
- Description:
- IC BUFFER INVERT 6V 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,385
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Product details
Overview
SN74HC540PW from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for bus interface and data routing in 2–6 V digital systems. It delivers ±6 mA output drive at 5 V, features typical propagation delay of 8 ns, supports up to 15 LSTTL loads, and operates across −40°C to +85°C - used in industrial control backplanes and microcontroller I/O expansion.
For engineers reviewing the SN74HC540PW datasheet, SN74HC540PW pinout, SN74HC540PW application, or SN74HC540PW equivalent, key selection criteria include its inverted 3-state logic architecture, TSSOP-20 package footprint, low ICC (80 μA max), high noise immunity (VIH/VIL thresholds defined per VCC), and compatibility with HC-series timing and voltage levels.
Technical Context
The SN74HC540PW implements eight independent inverting buffers, each with complementary 3-state control via dual OE inputs (OE1, OE2) wired as a NOR gate - enabling full output disable when either OE is high. Its CMOS design ensures rail-to-rail input thresholds and symmetrical output swing.
It uses standard HC logic family characteristics: TTL-compatible input thresholds at VCC = 4.5 V and 6 V, guaranteed 3-state leakage ≤5 μA at 6 V, and switching performance validated at CL = 50 pF and CL = 150 pF. Thermal resistance RθJA is 131.8°C/W in the TSSOP-20 package.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Function | Inverting octal buffer with 3-state outputs - enables bidirectional bus control via active-low enable logic. |
| Supply Voltage Range | 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 VCC = 5 V - directly drives 15 LSTTL loads without external buffers. |
| Propagation Delay | Typical 8 ns at VCC = 4.5 V, CL = 50 pF - ensures timing compliance in high-speed address/data latching. |
| Quiescent Current | 80 μA max at VCC = 6 V - enables low-power standby in battery-backed or energy-sensitive designs. |
| Input Leakage | ±1 μA max - prevents floating-input-induced current paths and ensures stable logic states. |
| 3-State Leakage | ±5 μA max at VCC = 6 V - minimizes bus contention current during high-impedance mode. |
Pinout & Package
TSSOP-20 package (6.50 mm × 4.40 mm, 1.2 mm max height), JEDEC MO-153 compliant, with exposed pad not electrically connected. Pin 1 index located at top-left corner; pins numbered counterclockwise.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | Inputs (A1–A8) | Active-high data inputs; inverted logic passed to corresponding Y outputs. |
| 9, 10 | Output Enables (OE1, OE2) | NOR-gated 3-state control: outputs go high-Z if either OE is high. |
| 11, 13, 14, 15, 16, 17, 18, 20 | Outputs (Y1–Y8) | Inverted buffered outputs; drive bus lines or LSTTL loads directly. |
| 12, 19 | Power (GND, VCC) | Dual power pins improve noise immunity and reduce ground bounce in high-speed switching. |
Key Features
| Feature | Design Value |
|---|---|
| Data flow-through pinout | Inputs on left side (pins 1–8), outputs on right side (pins 11,13–20) - simplifies PCB trace routing and reduces layer count. |
| Inverted 3-state logic | OE-controlled high-impedance state with guaranteed <5 μA leakage - enables clean bus sharing without pull-up conflicts. |
| Low dynamic power | 35 pF typical power dissipation capacitance per buffer - minimizes switching current and EMI in dense layouts. |
| Rail-to-rail input thresholds | VIH = 3.15 V / VIL = 1.35 V at VCC = 4.5 V - ensures robust noise margin (>1.3 V) in noisy industrial environments. |
| Wide temperature range | −40°C to +85°C operation - qualified for industrial-grade embedded systems including PLC I/O modules. |
Applications
| Industrial Backplane Interface | Microcontroller I/O Expansion |
|---|---|
Use Scenario: Isolating and buffering address/data lines between a main controller and multiple slave modules on a DIN-rail mounted PLC backplane. IC Role / Device Role / Timing Role: Inverting 3-state buffer providing direction-controlled bus isolation and signal integrity restoration. Use Value: Enables hot-swap capability and prevents bus contention during module insertion/removal using OE-driven high-Z state. |
Use Scenario: Expanding GPIO count of an ARM Cortex-M4 MCU to drive 8-channel LED indicators and relay drivers. IC Role / Device Role / Timing Role: Level-shifting and current-boosting buffer translating 3.3 V logic to 5 V peripheral interface. Use Value: Delivers ±6 mA per output at 5 V - eliminates need for discrete transistor arrays while maintaining timing predictability (tpd ≤ 25 ns). |
| Test Equipment Signal Routing | Legacy System Bus Interface |
Use Scenario: Multiplexing test signals between FPGA-based pattern generators and DUT connectors in automated test fixtures. IC Role / Device Role / Timing Role: Bidirectional signal conditioner with precise 3-state timing (ten/tdis ≤ 32 ns at 6 V). Use Value: Guarantees glitch-free bus transitions during reconfiguration, critical for deterministic test vector delivery. |
Use Scenario: Interfacing modern low-power microcontrollers to legacy 5 V parallel EEPROMs and LCD controllers. IC Role / Device Role / Timing Role: Voltage-tolerant bus driver supporting 2–6 V supply while maintaining HC timing compatibility. Use Value: Eliminates level translators; maintains tpd < 30 ns at 5 V - preserves setup/hold margins in legacy timing-critical designs. |
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); identical pinout and 3-state behavior. | Better suited for mixed 5 V TTL/CMOS systems where input noise immunity must match legacy TTL logic levels. | Select SN74HCT540PW when interfacing to 5 V TTL outputs; otherwise SN74HC540PW offers wider VCC flexibility (2–6 V). |
| 74LCX540MTCX | Lower VCC range (2–3.6 V), higher speed (tpd = 5.5 ns typ), and 3.6 V tolerant inputs - but not 5 V compatible. | Targeted for low-voltage portable/embedded systems; incompatible with 5 V buses due to absolute max rating of 3.6 V. | Choose 74LCX540MTCX only for sub-3.6 V domains requiring faster switching; SN74HC540PW remains optimal for 5 V or dual-voltage use. |
Compared with SN74HCT540PW and 74LCX540MTCX, the SN74HC540PW uniquely balances wide supply range (2–6 V), proven industrial temperature support, and direct 5 V bus compatibility - making it the default choice for general-purpose 3-state buffering where voltage flexibility and reliability are prioritized over marginal speed gains or strict TTL-level matching.
Availability
SN74HC540PW is available at Aetrix Electronics and suitable for industrial control backplanes, microcontroller I/O expansion, test equipment signal routing, and legacy system bus interface requiring stable component supply and long-term lifecycle support.
Supply support for SN74HC540PW 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 SN74HC540PW belongs to TI's 74HC high-speed CMOS logic product line, engineered for reliable bus interface, data routing, and I/O expansion in industrial, automotive, and communications equipment.
FAQ
What is the function of the dual OE inputs on the SN74HC540PW?
The SN74HC540PW uses two output-enable inputs (OE1 and OE2) configured as a NOR gate: if either OE1 or OE2 is driven high, all eight outputs enter high-impedance state. This provides redundant enable control and simplifies system-level bus arbitration logic. The SN74HC540PW does not require both OEs to be asserted - either one suffices to disable outputs.
Does the SN74HC540PW support 3.3 V operation?
Yes, the SN74HC540PW fully supports 3.3 V operation within its 2–6 V supply range. At VCC = 3.3 V, VIH is guaranteed ≥2.31 V and VIL ≤0.99 V per datasheet specifications, delivering >1.3 V noise margin. Output drive is reduced to ±4 mA typical, sufficient for driving modern 3.3 V logic loads.
Is the SN74HC540PW pin-compatible with the SN74HC240?
No, the SN74HC540PW is not pin-compatible with the SN74HC240. While both are octal 3-state buffers, the SN74HC240 is non-inverting and has different pin assignments: OE is single-ended and located on pin 1, whereas SN74HC540PW uses dual OE inputs (pins 9 and 10) and inverts data. Board layout and firmware logic must be redesigned for substitution.
What is the maximum capacitive load the SN74HC540PW can drive reliably?
The SN74HC540PW is characterized up to 150 pF load capacitance, with switching parameters (tpd, ten, tdis) specified at both CL = 50 pF and CL = 150 pF. Driving >150 pF may increase propagation delay and transition time beyond datasheet limits; for heavier loads, add series termination or consider a dedicated bus driver with higher Cpd tolerance.
How does the SN74HC540PW handle unused inputs?
All unused inputs on the SN74HC540PW must be tied to a valid logic level - either VCC or GND - to prevent floating nodes that cause excessive ICC, oscillation, or undefined output states. Leaving inputs unconnected violates TI's recommended operating conditions and risks device malfunction. This applies to both data inputs (A1–A8) and OE inputs (OE1, OE2).
SN74HC540PW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- 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:
- 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
SN74HC540PW FAQ
1.How can I place an order for SN74HC540PW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC540PW 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 SN74HC540PW reliable?
The price and inventory of SN74HC540PW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC540PW is usually 5 days.
3.What payment methods are accepted for SN74HC540PW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC540PW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC540PW?
SN74HC540PW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC540PW 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 SN74HC540PW?
For technical support, including SN74HC540PW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC540PW requirements.
6.How does Aetrix verify that SN74HC540PW is sourced from the original manufacturer or authorized distributors?
All SN74HC540PW 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 SN74HC540PW meets industry standards.
7.What is the process for return or replacement of SN74HC540PW?
All SN74HC540PW units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC540PW, 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 SN74HC540PW part is unused and in its original packaging.
Return procedure for SN74HC540PW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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