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Texas Instruments CD74HCT540E
- Part No.:
- CD74HCT540E
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
CD74HCT540E.pdf
- Description:
- IC BUFFER INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:961
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Product details
Overview
CD74HCT540E from Texas Instruments is an inverting octal buffer and line driver with three-state outputs, designed for bus-oriented applications requiring high drive strength (15 LSTTL loads), 5 V logic compatibility, and wide temperature operation (–55℃ to 125℃). It features dual output enable inputs (OE1/OE2), 9 ns typical propagation delay at 5 V/15 pF, and CMOS input compatibility with ≤1 μA leakage.
For engineers reviewing the CD74HCT540E datasheet, CD74HCT540E pinout, CD74HCT540E application, or CD74HCT540E equivalent, this page delivers verified functional identity, validated PDIP-20 pin mapping, confirmed HCT-series electrical behavior, and real-world selection guidance for industrial bus interface and memory address buffering.
Technical Context
The CD74HCT540E implements eight independent inverting buffers, each with three-state output control governed by the logical AND of OE1 and OE2 - both must be LOW for active output; either HIGH forces high-impedance state. Its HCT logic family ensures TTL-compatible input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V) and CMOS-level output drive under 4.5–5.5 V supply.
It operates across –55℃ to 125℃ with guaranteed switching performance: tPLH/tPHL ≤ 36 ns (CL = 50 pF), tPLZ/tPHZ ≤ 53 ns (enable/disable), and balanced transition times (tTHL/tTLH ≤ 18 ns). Input capacitance is 10 pF; three-state output capacitance is 20 pF; power dissipation capacitance is 55 pF.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | HCT - TTL-compatible inputs, CMOS outputs, 4.5–5.5 V operation |
| Function | Inverting octal buffer with three-state outputs, dual enable (OE1 & OE2) |
| Drive Strength | 15 LSTTL loads - sufficient for driving long PCB traces or multiple downstream inputs |
| Propagation Delay | 9 ns typical (5 V, CL = 15 pF) - enables reliable timing in 30+ MHz bus systems |
| Operating Temperature | –55℃ to 125℃ - qualified for aerospace, automotive under-hood, and industrial control environments |
| Input Leakage | ≤1 μA at VOH/VOL - minimizes static current draw in high-impedance bus states |
| Three-State Leakage | ±10 μA max (VO = VCC/GND) - ensures clean bus isolation during disable |
Pinout & Package
CD74HCT540E is supplied in a 20-pin Plastic Dual Inline Package (PDIP-N), with nominal body dimensions 25.40 mm × 6.35 mm and 2.54 mm lead pitch. The package is through-hole mountable, RoHS-compliant (NIPDAU finish), and rated for operation from –55℃ to 125℃.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | Inputs (A0–A7) | Inverting data inputs - drive corresponding outputs Y0–Y7 when enabled |
| 9, 10, 11, 12, 13, 14, 15, 16 | Outputs (Y0–Y7) | Inverted buffered outputs - high-impedance when OE1 or OE2 is HIGH |
| 17 | Ground (GND) | Reference return path for all signals and power |
| 18 | OE2 | Active-low output enable - HIGH forces all Y0–Y7 into high-Z state |
| 19 | VCC | Positive supply rail (4.5–5.5 V) - powers internal logic and output drivers |
| 20 | OE1 | Active-low output enable - HIGH forces all Y0–Y7 into high-Z state |
Key Features
| Feature | Design Value |
|---|---|
| Inverting octal buffering | Provides signal polarity inversion while isolating source from load - essential for address/data bus inversion in legacy microprocessor systems |
| Dual active-low output enables | Enables hierarchical bus control - e.g., OE1 from system controller, OE2 from local peripheral, allowing coordinated bus arbitration |
| 15-LSTTL load drive capability | Supports fanout to multiple TTL inputs without external amplification - reduces component count on memory or I/O expansion cards |
| Wide temperature range (–55℃ to 125℃) | Validated for use in uncontrolled environments including military chassis, motor drives, and avionics subsystems |
| Low quiescent current (≤160 μA) | Minimizes standby power in battery-backed or energy-sensitive systems - critical for always-on monitoring nodes |
Applications
| Industrial PLC Backplane Interface | Legacy Microprocessor Address Buffering |
|---|---|
|
Use Scenario: Isolating and driving 8-bit address lines between CPU and multiple peripheral modules on a DIN-rail mounted PLC backplane. IC Role / Device Role / Timing Role: Inverting address buffer with three-state control - enables time-multiplexed access to shared memory-mapped peripherals. Use Value: 15-LSTTL drive strength ensures signal integrity over 150 mm backplane traces; dual OE pins allow precise timing-controlled bus release per module. |
Use Scenario: Buffering inverted address bits (A0–A7) from Z80 or 8085 CPU to EPROM and I/O port chips on a retro-computing development board. IC Role / Device Role / Timing Role: Level-shifting and fanout buffer - converts CPU's low-drive address outputs to robust TTL-compatible signals. Use Value: 9 ns propagation delay meets Z80's 250 ns address setup window; HCT input thresholds guarantee reliable sampling of CPU's marginal logic levels. |
| Automotive ECU Diagnostic Bus Driver | Test Equipment Signal Conditioning |
|
Use Scenario: Driving diagnostic command lines (e.g., K-line or proprietary serial bus) from MCU to multiple sensor clusters in engine control units. IC Role / Device Role / Timing Role: Three-state line driver - allows MCU to share bidirectional diagnostic bus with multiple ECUs via hardware arbitration. Use Value: –55℃ to 125℃ rating supports under-hood deployment; ±10 μA three-state leakage prevents false triggering during bus idle periods. |
Use Scenario: Conditioning digital stimulus signals from pattern generators before injecting into DUTs during ATE functional testing. IC Role / Device Role / Timing Role: Inverting buffer with controlled edge rates - reshapes fast-rising test vectors to meet DUT input slew requirements. Use Value: 12–18 ns output transition time (CL = 50 pF) suppresses harmonic content above 30 MHz, reducing EMI in calibrated test 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 |
|---|---|---|---|
| SN74HCT240N | Same HCT family, identical pinout (PDIP-20), but includes two independent 4-bit sections with separate enables - no dual-OE per 8-bit group | Preferred where modular enable control (e.g., per 4-bit nibble) is required instead of unified 8-bit enable | Select SN74HCT240N if partial bus gating (e.g., upper/lower byte) is needed; CD74HCT540E remains optimal for full 8-bit synchronous enable. |
| CD74HCT540M96 | SOIC-20 surface-mount variant of same device - identical logic, timing, and DC specs; differs only in package (DW vs N) and thermal resistance (RθJA = 109.1°C/W vs 84.6°C/W) | Required for automated SMT assembly; unsuitable for through-hole prototyping or repair | Choose CD74HCT540M96 for volume production PCBs; CD74HCT540E remains preferred for lab validation, field repair, and breadboard integration. |
Compared with SN74HCT240N, CD74HCT540E provides unified 8-bit enable control ideal for simple bus drivers, while CD74HCT540M96 offers identical functionality in SOIC for space-constrained layouts - neither is pin-compatible with CD74HCT540E due to differing package footprints and thermal profiles.
Availability
CD74HCT540E is available at Aetrix Electronics and suitable for industrial PLC backplanes, legacy microprocessor address buffering, and automotive ECU diagnostic interfaces requiring stable component supply, long-term obsolescence management, and extended temperature support.
Supply support for CD74HCT540E 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 delivering analog, embedded processing, and logic solutions with emphasis on reliability, longevity, and industrial-grade qualification.
The CD74HCT540E belongs to TI's legacy HC/HCT logic family - engineered for drop-in replacement of obsolete TTL devices while delivering lower power, higher noise immunity, and extended temperature operation in industrial and aerospace systems.
FAQ
What is the supply voltage range for CD74HCT540E?
The CD74HCT540E operates within a strict 4.5 V to 5.5 V supply range, as defined by its HCT logic family specification. Operation outside this window - including 3.3 V or 6 V - is not guaranteed and may result in undefined output states or excessive ICC. This range ensures TTL-compatible input thresholds and robust CMOS output drive for legacy system integration.
How does the dual output enable (OE1 and OE2) function on CD74HCT540E?
On CD74HCT540E, both OE1 and OE2 must be driven LOW simultaneously to activate the eight inverting outputs (Y0–Y7); if either OE1 or OE2 is HIGH, all outputs enter high-impedance state. This AND-gated enable logic allows fail-safe bus release - for example, one enable can be tied to system reset, the other to peripheral select, ensuring outputs remain disabled unless both conditions are met.
Can CD74HCT540E drive standard TTL loads reliably?
Yes, CD74HCT540E is explicitly rated to drive 15 LSTTL loads, verified across –55℃ to 125℃. At VCC = 4.5 V, it guarantees VOL ≤ 0.4 V at IOL = 6 mA and VOH ≥ 3.7 V at IOH = –6 mA - exceeding standard TTL voltage margins. This makes it suitable for direct interfacing with 74LS, 74ALS, and similar families without level-shifting circuitry.
What is the maximum propagation delay for CD74HCT540E under worst-case conditions?
The maximum propagation delay (tPLH/tPHL) for CD74HCT540E is 36 ns under worst-case conditions: VCC = 4.5 V, CL = 50 pF, and temperature = –55℃ to 125℃. This value is specified in the datasheet's "Switching Characteristics" table and ensures timing compliance in systems with ≥25 MHz clock domains when used in address or control path buffering.
Is CD74HCT540E pin-compatible with CD74HC540E?
No, CD74HCT540E is not pin-compatible with CD74HC540E in functional operation despite identical pinout and package. While both share the same PDIP-20 footprint and terminal assignments, their input threshold specifications differ: CD74HCT540E requires VIH ≥ 2.0 V (TTL-compatible), whereas CD74HC540E requires VIH ≥ 3.15 V (CMOS-level) at 4.5 V - substituting one for the other risks logic misreads in mixed-signal systems.
CD74HCT540E Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- 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:
- 6mA, 6mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
CD74HCT540E FAQ
1.How can I place an order for CD74HCT540E through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HCT540E 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 CD74HCT540E reliable?
The price and inventory of CD74HCT540E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HCT540E is usually 5 days.
3.What payment methods are accepted for CD74HCT540E?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HCT540E transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HCT540E?
CD74HCT540E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HCT540E 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 CD74HCT540E?
For technical support, including CD74HCT540E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HCT540E requirements.
6.How does Aetrix verify that CD74HCT540E is sourced from the original manufacturer or authorized distributors?
All CD74HCT540E 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 CD74HCT540E meets industry standards.
7.What is the process for return or replacement of CD74HCT540E?
All CD74HCT540E units undergo pre-shipment inspection (PSI). If there is an issue with CD74HCT540E, 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 CD74HCT540E part is unused and in its original packaging.
Return procedure for CD74HCT540E:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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