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Texas Instruments CD74AC540ME4
- Part No.:
- CD74AC540ME4
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
CD74AC540ME4.pdf
- Description:
- IC BUFF INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,894
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Product details
Overview
CD74AC540ME4 from Texas Instruments is an octal inverting 3-state buffer/line driver with dual active-low output enables, designed for high-speed bus interface and data routing in industrial and military-grade systems. It operates from 1.5V to 5.5V, delivers ±24mA output drive, supports 50Ω transmission-line driving, and features balanced propagation delays (6.2ns typical at 5V) and SCR-latchup-resistant CMOS process.
For engineers reviewing the CD74AC540ME4 datasheet, CD74AC540ME4 pinout, CD74AC540ME4 application, or CD74AC540ME4 equivalent, this page provides verified functional mode definitions, truth table behavior, thermal resistance (101.2°C/W SOIC-20), ESD rating (±2000V HBM), and precise switching characteristics across temperature ranges from −55°C to +125°C.
Technical Context
The CD74AC540ME4 implements two independent active-low output enable controls (OE1, OE2) enabling selective tri-state control of eight inverting outputs (Q0–Q7). Its RCA Advanced CMOS architecture ensures TTL-compatible input thresholds and rail-to-rail output swing under load.
It supports simultaneous switching noise management via controlled output slew rates (≤10 ns/V at 5V), low dynamic power dissipation (CPD = 60 pF), and guaranteed 3-state leakage current ≤±10 µA over full temperature range - critical for high-density backplane and memory address buffering applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 1.5V to 5.5V - enables interoperability with mixed-voltage logic domains including 1.8V, 3.3V, and 5V systems |
| Output Drive Current | ±24mA per output - sufficient to directly drive 50Ω transmission lines or fan out to 15 FAST® ICs without external buffers |
| Propagation Delay | 6.2ns max at VCC = 5V, TA = −55°C to +125°C - ensures timing-critical bus hold and address strobe integrity |
| Input Thresholds | VIH = 3.85V, VIL = 1.65V at VCC = 5.5V - provides robust noise immunity with 30% supply margin |
| ESD Rating | ±2000V HBM - meets industrial handling requirements without additional protection circuitry |
| Thermal Resistance | RθJA = 101.2°C/W (SOIC-20) - defines maximum power dissipation limit (≈50mW) under natural convection |
| Operating Temperature | −55°C to +125°C - qualified for extended industrial and military embedded environments |
Pinout & Package
CD74AC540ME4 is packaged in a 20-pin SOIC (DW) with body size 12.8mm × 7.5mm and nominal package size 12.8mm × 10.3mm. Pin 1 is located at the top-left corner with notch or dot marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| !MR (Pin 1) | Master reset, active-low | Asynchronous global reset that forces all outputs to high-impedance state regardless of OE status |
| Q0–Q7 (Pins 2,5,6,9,12,15,16,19) | Inverting buffered outputs | Each output mirrors inverted logic level of corresponding D-input when enabled; tri-stated otherwise |
| D0–D7 (Pins 3,4,7,8,13,14,17,18) | Data inputs | Eight independent logic inputs routed through inverting buffers to Q0–Q7 |
| OE1, OE2 (Pins not explicitly numbered in provided table but functionally defined as dual enables) | Active-low output enables | Both must be low to enable outputs; either high disables all eight outputs into high-impedance state |
| VCC (Pin 20) | Positive supply | Primary power rail; requires local 0.1µF bypass capacitor per device |
| GND (Pin 10) | Ground reference | Common return path for all I/O and internal logic; must be low-inductance connection |
Key Features
| Feature | Design Value |
|---|---|
| SCR-latchup resistance | Guaranteed immunity to latch-up under transient overvoltage conditions per JEDEC JESD78, eliminating need for external current limiting |
| Balanced propagation delays | Matched tPLH/tPHL within ±0.5ns across all eight channels - essential for skew-sensitive address/data buses |
| 3-state output control | Dual independent OE pins allow partitioned bus arbitration - e.g., OE1 for upper nibble, OE2 for lower nibble |
| Wide voltage operation | 1.5V–5.5V supply range supports direct interfacing with legacy 5V microcontrollers and modern 1.8V FPGAs |
| Transmission-line drive | Validated 50Ω line drive capability at +85°C and 75Ω at +125°C - enables point-to-point or stubbed bus topologies |
Applications
| Industrial PLC Backplane Interface | Military Avionics Data Bus Buffering |
|---|---|
Use Scenario: Isolating and driving address/data signals between CPU module and I/O expansion slots in ruggedized programmable logic controllers. IC Role / Device Role / Timing Role: Inverting 3-state buffer providing bidirectional bus isolation, slew-controlled edge timing, and hot-swap-safe high-Z state during slot insertion/removal. Use Value: Enables deterministic signal integrity across 20cm backplane traces at 25MHz clock rates while surviving −40°C to +85°C ambient cycling. | Use Scenario: Interfacing mission-critical sensor data streams (e.g., inertial measurement units) to flight control computers in airborne platforms. IC Role / Device Role / Timing Role: Octal buffer conditioning analog-to-digital converter outputs prior to MIL-STD-1553B or ARINC 429 protocol encoding stages. Use Value: Delivers guaranteed −55°C to +125°C operation and ±2000V HBM ESD protection required for DO-160 Section 22 compliance. |
| Automotive Engine Control Unit (ECU) Memory Expansion | Test Equipment Digital Pattern Generator |
Use Scenario: Expanding external program memory access in automotive ECUs using parallel NOR flash devices with multiplexed address/data buses. IC Role / Device Role / Timing Role: Address latching and buffering stage ensuring setup/hold time margins for flash read cycles at 125°C junction temperature. Use Value: Provides 6.2ns max propagation delay and rail-to-rail output swing to meet AEC-Q100 Grade 1 timing budgets under thermal stress. | Use Scenario: Generating synchronized multi-channel digital stimulus waveforms in automated test equipment for ASIC validation. IC Role / Device Role / Timing Role: Output stage translating FPGA-generated pattern data into clean, low-skew, high-drive signals for DUT pin drivers. Use Value: Achieves <100ps inter-channel skew across all eight outputs due to matched internal delay paths and balanced layout. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AC540N | Same AC logic family, identical pinout and electrical specs; differs only in RoHS-compliant lead finish and TI's newer packaging standard | Identical functional behavior; validated for same industrial temperature range (−40°C to +85°C) | Select SN74AC540N for new designs requiring TI's current production release and full RoHS compliance documentation |
| 74VHC540M | Higher VCC max (7V), lower ICC (2µA typical), but reduced drive (±8mA) and no −55°C to +125°C qualification | Limited to commercial/industrial temp range; insufficient for military or extended-temperature automotive use | Choose 74VHC540M only where ultra-low quiescent current dominates over drive strength and temperature range |
Compared with SN74AC540N, CD74AC540ME4 offers identical functionality with legacy marking and long-term military-grade availability; versus 74VHC540M, it trades lower static power for superior drive, noise immunity, and extended temperature support - making it irreplaceable in harsh-environment bus interface roles.
Availability
CD74AC540ME4 is available at Aetrix Electronics and suitable for industrial PLC backplanes, military avionics data buses, and automotive ECU memory expansion requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for CD74AC540ME4 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 50 years of high-reliability component design heritage.
The CD74AC540ME4 belongs to TI's legacy Advanced CMOS (AC) logic family, engineered specifically for robust, low-power, high-speed bus interface in aerospace, defense, and industrial control systems demanding extended temperature operation and latch-up immunity.
FAQ
What is the function of the !MR pin on CD74AC540ME4?
The !MR (Master Reset) pin on CD74AC540ME4 is an asynchronous active-low input that forces all eight outputs into high-impedance state regardless of OE1/OE2 status. This feature enables system-level fault recovery and safe power-up sequencing. Unlike OE controls, !MR overrides all internal logic states and is fully functional across the entire −55°C to +125°C operating range specified for CD74AC540ME4.
Does CD74AC540ME4 support 3.3V-only operation?
Yes, CD74AC540ME4 fully supports 3.3V operation: its recommended VCC range includes 3.3V (within 1.5V–5.5V), input thresholds (VIH = 2.1V, VIL = 0.9V at VCC = 3V) are compatible with 3.3V LVTTL, and output drive (±24mA) exceeds 3.3V bus requirements. All AC-series timing parameters - including 8.6ns max propagation delay at 3.3V - are characterized and guaranteed for CD74AC540ME4 at this voltage.
How does CD74AC540ME4 differ from CD74ACT540 variants?
CD74AC540ME4 uses AC-series CMOS with 1.5V–5.5V operation and TTL-compatible inputs, while CD74ACT540 variants use ACT-series (TTL-compatible output levels) with 4.5V–5.5V only. CD74AC540ME4 achieves lower ICC (80µA max vs. ACT's 8mA additional load per TTL input) and wider voltage flexibility, but CD74ACT540 offers faster propagation (6.5ns vs. 6.2ns typical) at 5V. Both share identical pinout and 3-state architecture.
Can CD74AC540ME4 drive 75Ω coaxial cables?
CD74AC540ME4 is characterized for 50Ω transmission-line drive at +85°C and 75Ω at +125°C per TI datasheet Section 4.5 footnote (2). While not optimized for 75Ω at room temperature, its ±24mA drive capability allows practical use with 75Ω lines in high-temperature environments (e.g., engine bays or avionics enclosures), provided termination is adjusted to maintain signal integrity - confirmed by measured VOHV/VOLP performance at 5V.
Is CD74AC540ME4 pin-compatible with CD74AC541 variants?
No, CD74AC540ME4 is not pin-compatible with CD74AC541 variants. Although both are 20-pin SOIC octal buffers, CD74AC540ME4 is inverting (Qn = NOT Dn), whereas CD74AC541 is non-inverting (Qn = Dn). Their pin functions match (D0–D7, Q0–Q7, OE1, OE2, VCC, GND), but logic polarity reversal means direct substitution would invert all data paths - requiring PCB redesign or firmware compensation. The CD74AC540ME4 datasheet explicitly distinguishes these families in Table 6-1 and 6-2 truth tables.
CD74AC540ME4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AC
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Discontinued at Digi-Key
- Logic Type:
- Buffer, Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 24mA, 24mA
- Voltage - Supply:
- 1.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
CD74AC540ME4 FAQ
1.How can I place an order for CD74AC540ME4 through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74AC540ME4 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 CD74AC540ME4 reliable?
The price and inventory of CD74AC540ME4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74AC540ME4 is usually 5 days.
3.What payment methods are accepted for CD74AC540ME4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74AC540ME4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74AC540ME4?
CD74AC540ME4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74AC540ME4 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 CD74AC540ME4?
For technical support, including CD74AC540ME4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74AC540ME4 requirements.
6.How does Aetrix verify that CD74AC540ME4 is sourced from the original manufacturer or authorized distributors?
All CD74AC540ME4 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 CD74AC540ME4 meets industry standards.
7.What is the process for return or replacement of CD74AC540ME4?
All CD74AC540ME4 units undergo pre-shipment inspection (PSI). If there is an issue with CD74AC540ME4, 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 CD74AC540ME4 part is unused and in its original packaging.
Return procedure for CD74AC540ME4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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