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Texas Instruments CD74HC540E
- Part No.:
- CD74HC540E
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
CD74HC540E.pdf
- Description:
- IC BUFFER INVERT 6V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:559
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Product details
Overview
CD74HC540E from Texas Instruments is an inverting octal buffer and line driver with three-state outputs, designed for bus interface and data routing in digital systems. It operates from 2 V to 6 V, delivers 15 LSTTL load drive capability, exhibits 9 ns typical propagation delay at 5 V/15 pF, and supports –55℃ to 125℃ industrial/military temperature range - used in backplane I/O buffering and memory address latching.
For engineers reviewing the CD74HC540E datasheet, CD74HC540E pinout, CD74HC540E application, or CD74HC540E equivalent, key selection criteria include its inverting logic function, dual output-enable control (OE1/OE2), high-impedance state behavior, wide supply voltage tolerance, and compatibility with both CMOS and TTL loads in noise-sensitive or thermally demanding environments.
Technical Context
The CD74HC540E implements eight independent inverting buffer channels, each with active-low output enable logic controlled by two shared OE inputs (OE1 and OE2). Its three-state outputs enter high-impedance mode when either OE1 or OE2 is HIGH, enabling bidirectional bus arbitration without external logic.
It uses standard HC CMOS process technology, delivering rail-to-rail output swing, balanced rise/fall times, and fanout of 10 standard TTL loads or 15 bus-driver TTL loads. Input thresholds scale with VCC (VIH = 70% VCC, VIL = 30% VCC), ensuring robust noise immunity across the full 2–6 V operating range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Function | Inverting octal buffer with three-state outputs - enables data inversion and bus isolation simultaneously. |
| Supply Voltage Range | 2 V to 6 V - supports mixed-voltage system interfacing and battery-powered operation down to 2 V. |
| Propagation Delay | 9 ns typical at VCC = 5 V, CL = 15 pF - ensures timing predictability in high-speed address/data paths. |
| Output Drive | 15 LSTTL loads - sufficient for driving long PCB traces or multiple downstream inputs without signal degradation. |
| Operating Temperature | –55℃ to 125℃ - qualified for aerospace, automotive under-hood, and industrial control applications. |
| Input Thresholds | VIH = 3.15 V, VIL = 1.35 V at VCC = 4.5 V - provides 30% noise margin, reducing susceptibility to ground bounce or EMI. |
| Three-State Leakage | ±5 μA max at –55℃ to 125℃ - minimizes standby current in powered-down bus segments. |
Pinout & Package
CD74HC540E is housed in a 20-pin plastic dual in-line package (PDIP-N), with 25.40 mm × 6.35 mm body size, through-hole mounting, and industry-standard pin spacing (2.54 mm).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | Inputs (A0–A7) | Active-HIGH data inputs; inverted and gated before reaching outputs. |
| 9, 10, 11, 12, 13, 14, 15, 16 | Outputs (Y0–Y7) | Inverted, three-state outputs; driven only when OE1 = OE2 = LOW. |
| 17, 18 | Output Enables (OE1, OE2) | Active-LOW enables; either HIGH forces all Y0–Y7 into high-impedance state. |
| 19 | GND | Ground reference for logic and power return path. |
| 20 | VCC | Positive supply rail (2–6 V); bypass capacitor required per TI layout guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| Inverting three-state logic | Enables bus contention avoidance while preserving signal polarity inversion required in address/data inversion paths. |
| Dual output-enable architecture | Allows hierarchical bus control - e.g., OE1 for subsystem-level enable, OE2 for channel-group gating. |
| 15-LSTTL load drive | Eliminates need for external bus transceivers in medium-complexity backplanes or memory modules. |
| Wide 2–6 V supply range | Permits direct interface with 3.3 V microcontrollers and 5 V legacy peripherals without level shifters. |
| –55℃ to 125℃ operation | Supports deployment in unheated outdoor enclosures or engine-control units without derating. |
Applications
| Memory Address Buffering | Industrial PLC Backplane Interface |
|---|---|
Use Scenario: Buffering and inverting CPU address lines before driving multiple memory chips on a shared bus. IC Role / Device Role / Timing Role: Inverting octal buffer with three-state outputs isolates CPU from memory loading and enables address multiplexing. Use Value: Maintains signal integrity across 15 LSTTL loads while supporting fast 9 ns propagation for synchronous memory access timing. | Use Scenario: Interfacing programmable logic controller (PLC) CPU modules to I/O expansion racks via parallel backplane. IC Role / Device Role / Timing Role: Bus driver providing noise-immune, high-drive-strength signals between isolated rack segments. Use Value: Dual OE control allows hot-swap-safe bus arbitration; wide temperature range ensures reliability in factory-floor cabinets. |
| Legacy System Level Shifter | Military Data Acquisition Front-End |
Use Scenario: Adapting 3.3 V FPGA outputs to 5 V legacy peripheral interfaces in retrofitted instrumentation. IC Role / Device Role / Timing Role: Voltage-tolerant inverting buffer translating logic levels while adding bus isolation. Use Value: 2–6 V operation eliminates discrete level-shifting components; 30% noise margin prevents false triggering in electrically noisy labs. | Use Scenario: Conditioning sensor data bus signals in airborne telemetry units exposed to extreme thermal cycling. IC Role / Device Role / Timing Role: Radiation-tolerant (per CD54HC family heritage), high-reliability bus driver with deterministic timing. Use Value: –55℃ to 125℃ qualification and low ICC (≤160 μA) support extended mission life in sealed avionics enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HC240N | Same inverting octal buffer function, identical PDIP-20 package, but features independent OE per group (4-channel pairs) instead of dual global OE. | Preferred where fine-grained bus segment control is needed - e.g., separate enable for address vs. data lanes. | Select SN74HC240N if group-level enable granularity improves system-level bus arbitration logic. |
| CD74HCT540E | Pin-compatible HCT variant with TTL-compatible input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V) and 4.5–5.5 V only operation. | Required when interfacing directly to legacy 5 V TTL logic without level translation. | Choose CD74HCT540E for strict LSTTL input compatibility in pure 5 V systems; CD74HC540E preferred for mixed-voltage or low-VCC designs. |
Compared with SN74HC240N and CD74HCT540E, the CD74HC540E offers broader supply flexibility (2–6 V) and simpler dual-OE control, making it optimal for new designs requiring voltage scalability and minimal enable logic overhead - whereas SN74HC240N suits segmented bus architectures and CD74HCT540E fits legacy TTL-only environments.
Availability
CD74HC540E is available at Aetrix Electronics and suitable for industrial control systems, aerospace data buses, and military-grade embedded computing requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for CD74HC540E 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 over 90 years of innovation in high-reliability IC design and manufacturing.
The CD74HC540E belongs to TI's CD74HC high-speed CMOS logic family, engineered for robust performance in harsh environments - targeting applications demanding wide temperature operation, low power, and interoperability across voltage domains.
FAQ
What logic function does the CD74HC540E implement?
The CD74HC540E implements an inverting octal buffer with three-state outputs. Each of its eight input channels (A0–A7) drives a corresponding inverted output (Y0–Y7), which enters high-impedance state when either OE1 or OE2 is HIGH. This function is confirmed in TI's SCHS189E datasheet Section 2 and Truth Table 7-1, and distinguishes CD74HC540E from non-inverting variants like CD74HC541E.
What is the recommended supply voltage range for CD74HC540E?
The CD74HC540E operates from 2 V to 6 V DC, as specified in Section 5.2 "Recommended Operating Conditions" of the TI datasheet. Operation outside this range risks functional failure or damage; at 2 V, VIH is 1.5 V and propagation delay increases to 110 ns (CL = 50 pF), while at 6 V, VOH reaches 5.9 V and delay drops to 19 ns - all verified in Electrical Characteristics tables.
How does the three-state enable logic work on CD74HC540E?
The CD74HC540E uses two active-LOW output enable inputs: OE1 (pin 17) and OE2 (pin 18). As stated in Section 7.3, if either OE1 or OE2 is HIGH, all eight outputs (Y0–Y7) go to high-impedance state regardless of input values. Only when both OE1 and OE2 are LOW do the outputs actively drive inverted logic levels - a feature validated in the Truth Table and Functional Diagram of the CD74HC540E datasheet.
Can CD74HC540E drive standard TTL loads?
Yes, the CD74HC540E can drive up to 15 LSTTL loads, as explicitly stated in the Features section and Section 7.1 Overview of the TI datasheet. Its output drive strength (IO = ±25 mA per pin, VOH ≥ 3.98 V at IOH = –6 mA, VOL ≤ 0.4 V at IOL = 6 mA, VCC = 4.5 V) meets or exceeds standard TTL voltage and current requirements, enabling direct interface without buffers in most legacy systems.
Is CD74HC540E compatible with 3.3 V microcontroller I/O?
Yes, CD74HC540E is fully compatible with 3.3 V microcontrollers. At VCC = 3.3 V, its input thresholds are VIH ≈ 2.31 V and VIL ≈ 0.99 V (30%/70% of VCC), comfortably exceeding typical 3.3 V MCU output levels (VOH ≥ 2.4 V, VOL ≤ 0.4 V). Output swing is rail-to-rail, so it drives 3.3 V inputs reliably - confirmed in Electrical Characteristics Tables 5.4 and TI application guidance.
CD74HC540E Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- 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:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
CD74HC540E FAQ
1.How can I place an order for CD74HC540E through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HC540E 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 CD74HC540E reliable?
The price and inventory of CD74HC540E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HC540E is usually 5 days.
3.What payment methods are accepted for CD74HC540E?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HC540E transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HC540E?
CD74HC540E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HC540E 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 CD74HC540E?
For technical support, including CD74HC540E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HC540E requirements.
6.How does Aetrix verify that CD74HC540E is sourced from the original manufacturer or authorized distributors?
All CD74HC540E 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 CD74HC540E meets industry standards.
7.What is the process for return or replacement of CD74HC540E?
All CD74HC540E units undergo pre-shipment inspection (PSI). If there is an issue with CD74HC540E, 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 CD74HC540E part is unused and in its original packaging.
Return procedure for CD74HC540E:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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