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Texas Instruments CD74HCT540M
- Part No.:
- CD74HCT540M
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
CD74HCT540M.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,367
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Product details
Overview
CD74HCT540M from Texas Instruments is an inverting octal buffer and line driver with three-state outputs, designed for bidirectional bus interfacing in industrial control and data acquisition systems. It operates at 4.5–5.5 V, delivers 15 LSTTL load drive capability, exhibits 9 ns typical propagation delay (VCC = 5 V, CL = 15 pF), and supports –55°C to +125°C operating temperature.
For engineers reviewing the CD74HCT540M datasheet, CD74HCT540M pinout, CD74HCT540M application, or CD74HCT540M equivalent, this page provides verified functional mode behavior, SOIC-20 package layout, bus-driving performance metrics, and validated alternatives for legacy system upgrades and high-reliability embedded designs.
Technical Context
The CD74HCT540M implements dual independent output-enable controls (OE1 and OE2) - either high forces all eight outputs into high-impedance state, while simultaneous low enables inverting data transfer from A0–A7 to Y0–Y7. Its HCT logic family ensures direct compatibility with LSTTL input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V) while maintaining CMOS power efficiency.
It features buffered inputs, balanced rise/fall times, and bus-line driving capability up to 15 LSTTL loads. Absolute maximum ratings include ±35 mA per output sink/source and junction temperature up to 150°C, supporting operation in harsh thermal environments without derating under nominal conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | HCT - TTL-compatible input thresholds, 4.5–5.5 V supply, CMOS power profile |
| Propagation Delay | 9 ns typical (5 V, 15 pF) - enables reliable timing in 30+ MHz bus cycles |
| Output Drive | 15 LSTTL loads - sufficient for driving multiple legacy TTL devices on shared data buses |
| Operating Temp | –55°C to +125°C - qualified for aerospace, automotive engine control, and industrial PLC modules |
| Three-State Leakage | ±5 μA max (–55°C to +125°C) - ensures minimal bus contention current during high-Z state |
| Input Leakage | ±1 μA max (5.5 V, full temp range) - prevents unintended logic transitions on unterminated inputs |
| Quiescent Current | 160 μA max (–55°C to +125°C) - supports low-power standby modes in battery-backed systems |
Pinout & Package
CD74HCT540M is housed in a 20-pin SOIC (DW) package measuring 12.80 mm × 7.50 mm, with standard 0.65 mm lead pitch and RoHS-compliant NiPdAu lead finish. The package carries MSL Level-1 rating (260°C peak reflow, unlimited floor life).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A0–A7 Inputs | Inverting data inputs; buffered for noise immunity and fan-in stability |
| 9, 10, 11, 13, 14, 15, 16, 17 | Y0–Y7 Outputs | Three-state inverting outputs; each capable of sinking 25 mA or sourcing 25 mA |
| 12 | GND | Ground reference for all logic and I/O; must be low-inductance connection |
| 20 | VCC | Positive supply (4.5–5.5 V); requires local 0.1 μF bypass capacitor |
| 18 | OE1 | Active-low output enable #1; high forces all Y outputs to high-Z |
| 19 | OE2 | Active-low output enable #2; high forces all Y outputs to high-Z |
Key Features
| Feature | Design Value |
|---|---|
| Inverting octal buffering | Provides signal polarity inversion with gain-of-one amplification for bus-level signal conditioning |
| Dual independent output enables | OE1 and OE2 allow hierarchical bus arbitration - partial enable/disable without external logic |
| LSTTL load compatibility | Drives 15 LSTTL loads directly - eliminates need for external bus transceivers in mixed-logic systems |
| Wide temperature operation | –55°C to +125°C range supports deployment in unheated outdoor enclosures and under-hood automotive ECUs |
| Low dynamic power dissipation | CPD = 55 pF enables <1 mW/MHz per channel - critical for thermally constrained PCB layouts |
Applications
| Industrial Bus Interface | Legacy System Data Translation |
|---|---|
|
Use Scenario: Isolating and translating signals between microcontroller GPIO banks and legacy parallel peripheral buses (e.g., printer ports, memory-mapped I/O). IC Role / Device Role / Timing Role: Inverting octal buffer with three-state control acts as direction-controlled data path between MCU and external peripherals. Use Value: Enables clean bidirectional data flow using only two enable lines, reducing PCB routing complexity versus discrete gate solutions. |
Use Scenario: Upgrading aging industrial controllers where original TTL buffers have failed or become obsolete. IC Role / Device Role / Timing Role: Drop-in replacement for 74LS540 in existing PCBs, preserving timing margins due to sub-10 ns propagation delay. Use Value: Maintains system functionality while cutting quiescent current by >90% versus LS-TTL equivalents. |
| Automotive ECU Signal Conditioning | Test Equipment Digital I/O Expansion |
|
Use Scenario: Driving diagnostic interface lines in engine control units exposed to under-hood thermal cycling. IC Role / Device Role / Timing Role: Buffering sensor status bits and actuator command signals across noisy vehicle harnesses. Use Value: –55°C to +125°C rating and 15 LSTTL drive ensure robustness against voltage transients and thermal stress. |
Use Scenario: Expanding digital I/O channels on automated test equipment requiring precise timing and bus isolation. IC Role / Device Role / Timing Role: Providing synchronized, three-state-controlled outputs for stimulus generation and response capture. Use Value: Matched propagation delays and transition times minimize skew across all eight channels. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT540N | Same logic function, PDIP-20 package (25.4 mm × 6.35 mm), higher RθJA (84.6°C/W vs. 109.1°C/W) | Better suited for through-hole prototyping or legacy board rework; lower thermal performance in dense SMT layouts | Select when manual assembly or socket-based testing is required; verify thermal margin in enclosed enclosures |
| CD74HCT540M96 | Identical die and SOIC-20 package; differs only in tape-and-reel packaging (2000 pcs/reel vs. tube for M) | No functional or electrical difference; intended for automated SMT placement rather than hand-soldering | Preferred for volume production; same pinout, timing, and reliability - direct drop-in for pick-and-place lines |
Compared with SN74HCT540N and CD74HCT540M96, the CD74HCT540M offers identical core functionality but is supplied in tube packaging optimized for low-volume engineering validation and repair, while maintaining full qualification across the –55°C to +125°C range.
Availability
CD74HCT540M is available at Aetrix Electronics and suitable for industrial control, automotive diagnostics, and test equipment applications requiring stable component supply, long-term obsolescence management, and extended temperature-grade assurance.
Supply support for CD74HCT540M 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 ICs, with over 90 years of innovation in high-reliability electronic components.
The CD74HCT540M belongs to TI's legacy HCT logic family, engineered for seamless interoperability between CMOS and TTL systems in mission-critical industrial and automotive applications.
FAQ
What is the supply voltage range for CD74HCT540M?
The CD74HCT540M operates within a strict 4.5 V to 5.5 V supply range. Operation outside this window violates recommended conditions and may cause undefined logic states or increased ICC. This range ensures compatibility with standard 5 V TTL systems while maintaining CMOS-level power efficiency. Always decouple VCC with a 0.1 μF ceramic capacitor placed adjacent to pin 20 of the CD74HCT540M.
How does the three-state control work on CD74HCT540M?
The CD74HCT540M uses two active-low output enables: OE1 (pin 18) and OE2 (pin 19). If either is HIGH, all eight Y outputs enter high-impedance state regardless of input values. Only when both OE1 and OE2 are LOW do the inverted inputs A0–A7 appear at Y0–Y7. This dual-enable architecture allows flexible bus arbitration without external gating logic.
Is CD74HCT540M pin-compatible with 74LS540?
Yes - CD74HCT540M is pin-compatible with 74LS540 in SOIC-20 (DW) package, sharing identical pinout, pin functions, and mechanical footprint. However, CD74HCT540M draws significantly less quiescent current (≤160 μA vs. ~30 mA) and offers wider temperature support (–55°C to +125°C vs. 0°C to +70°C), making it a direct upgrade path.
What is the maximum output current per pin for CD74HCT540M?
The CD74HCT540M supports ±25 mA DC output current per Y pin under recommended operating conditions. Absolute maximum ratings permit ±35 mA short-term sink/source, but sustained operation above ±25 mA risks exceeding thermal limits in SOIC-20. For 15 LSTTL load drive, the device delivers 6 mA per output at VOH ≥ 3.7 V and VOL ≤ 0.4 V - verified across full temperature range.
Does CD74HCT540M require pull-up or pull-down resistors on unused inputs?
Yes - all unused A0–A7, OE1, and OE2 inputs on CD74HCT540M must be terminated to a defined logic level (VCC or GND) to prevent floating nodes. Uncontrolled inputs increase ICC, induce oscillation, and risk latch-up. TI recommends tying unused inputs directly to VCC or GND via short traces - no series resistors needed unless ESD protection is required per system-level requirements.
CD74HCT540M Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 20-SOIC (0.295", 7.50mm 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:
- 6mA, 6mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
CD74HCT540M FAQ
1.How can I place an order for CD74HCT540M through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HCT540M 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 CD74HCT540M reliable?
The price and inventory of CD74HCT540M are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HCT540M is usually 5 days.
3.What payment methods are accepted for CD74HCT540M?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HCT540M transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HCT540M?
CD74HCT540M orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HCT540M 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 CD74HCT540M?
For technical support, including CD74HCT540M datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HCT540M requirements.
6.How does Aetrix verify that CD74HCT540M is sourced from the original manufacturer or authorized distributors?
All CD74HCT540M 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 CD74HCT540M meets industry standards.
7.What is the process for return or replacement of CD74HCT540M?
All CD74HCT540M units undergo pre-shipment inspection (PSI). If there is an issue with CD74HCT540M, 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 CD74HCT540M part is unused and in its original packaging.
Return procedure for CD74HCT540M:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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