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STMicroelectronics M74HCT240B1R
- Part No.:
- M74HCT240B1R
- Manufacturer:
- STMicroelectronics
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
M74HCT240B1R.pdf
- Description:
- IC BUFFER INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,199
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Product details
Overview
M74HCT240B1R from STMicroelectronics is an octal 3-state inverting bus buffer IC with dual independent enable controls (1G and 2G), designed for bidirectional data bus isolation in digital systems. It delivers 15 ns typical propagation delay at VCC = 4.5 V, ±6 mA symmetrical output drive, and TTL-compatible input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V), enabling direct interface with legacy TTL logic in industrial control backplanes.
For engineers reviewing the M74HCT240B1R datasheet, M74HCT240B1R pinout, M74HCT240B1R application, or M74HCT240B1R equivalent, key selection criteria include its dual-gated 3-state architecture, guaranteed 125°C operation, low 4 µA ICC quiescent current, and DIP-20 package compatibility with legacy 74-series layouts.
Technical Context
This device implements two independent groups of four inverting buffers (1A→1Y and 2A→2Y), each controlled by dedicated active-low enable inputs (1G and 2G). All outputs enter high-impedance state when their respective enable is high, supporting time-multiplexed bus sharing.
It uses silicon gate C2MOS technology to achieve TTL-level input compatibility while maintaining CMOS power efficiency. Input protection diodes and symmetrical output impedance (|IOH| = IOL ≥ 6 mA) ensure robust noise immunity and consistent rise/fall times (tPLH ≅ tPHL) across temperature ranges from –55°C to +125°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Propagation Delay (tPD) | 15 ns typical at VCC = 4.5 V, CL = 50 pF - enables reliable 33 MHz bus operation with timing margin |
| Output Drive | ±6 mA min. - supports driving 10 LSTTL loads or 50 pF transmission lines without buffering |
| Input Thresholds | VIH ≥ 2.0 V, VIL ≤ 0.8 V - ensures interoperability with standard TTL logic families |
| Quiescent Current | 4 µA max. at TA = 25°C - minimizes standby power in battery-backed or energy-sensitive systems |
| Operating Voltage | 4.5–5.5 V - aligns with regulated 5 V supply rails in industrial and telecom infrastructure |
| Temperature Range | –55°C to +125°C - qualified for extended-temperature applications including automotive under-hood and base station modules |
| Output Leakage (IOZ) | ±10 µA max. at –55°C to +125°C - maintains high-impedance integrity during hot-swap or partial-power-down sequences |
Pinout & Package
Package: Plastic Dual In-line Package (DIP-20), 0.3 inch body width, through-hole mounting compatible with IPC-7351A SOIC-20 footprint adapters.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1G / 2G | Active-low group enable inputs - independently disable 1Y/2Y outputs to prevent bus contention |
| 2,4,6,8 / 11,13,15,17 | 1A1–1A4 / 2A1–2A4 | Inverting data inputs - logic inversion occurs before 3-state output stage |
| 3,5,7,9 / 12,14,16,18 | 1Y1–1Y4 / 2Y1–2Y4 | Inverting 3-state outputs - high-Z when G = HIGH; inverted logic level when G = LOW |
| 10 | GND | Digital ground reference - must be connected to system 0 V plane with low-inductance path |
| 20 | VCC | Positive supply - bypassed with 100 nF ceramic capacitor near pin for AC noise suppression |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 3-state control | Separate 1G/2G pins allow asymmetric bus arbitration - e.g., isolate CPU address vs. data paths independently |
| TTL-compatible inputs | VIH/VIL thresholds match 74LS family, eliminating level-shifter requirements in mixed-logic designs |
| Balanced propagation delays | tPLH ≅ tPHL ensures minimal duty-cycle distortion on clock or strobe signals routed through buffer |
| Symmetrical output impedance | |IOH| = IOL ≥ 6 mA guarantees matched rise/fall times and reduced EMI in high-speed switching |
| ESD-protected inputs | Integrated diode clamps withstand ±2 kV HBM - reduces need for external TVS on board-level I/O interfaces |
Applications
| Industrial PLC Backplane | Legacy System Bus Isolation |
|---|---|
Use Scenario: Bidirectional data routing between CPU module and I/O expansion cards in modular programmable logic controllers. IC Role / Device Role / Timing Role: Octal inverting buffer with per-group 3-state control isolates address/data buses during card hot-swap or firmware update. Use Value: Prevents bus contention during reconfiguration; 125°C rating supports operation in uncooled control cabinets. | Use Scenario: Interfacing modern microcontrollers to vintage 74LS-based peripheral boards in test equipment upgrades. IC Role / Device Role / Timing Role: Level-translating bus driver that accepts TTL input levels while delivering CMOS-compatible output swing and drive strength. Use Value: Eliminates discrete resistor networks or dedicated level shifters; 15 ns delay preserves timing margins in 20 MHz bus cycles. |
| Telecom Line Card Buffering | Automotive Diagnostic Interface |
Use Scenario: Signal conditioning and isolation for serial control buses (e.g., HDLC or proprietary UART links) in carrier-grade line cards. IC Role / Device Role / Timing Role: Inverting 3-state buffer provides galvanic separation and drive reinforcement for long-trace RS-485 or LVDS stubs. Use Value: ±6 mA drive sustains signal integrity over 15 cm FR4 traces; –55°C to +125°C range meets NEBS GR-63-CORE environmental specs. | Use Scenario: Enabling/disabling diagnostic communication paths (e.g., K-Line or ISO 9141-2) between ECU and service tool during vehicle ignition cycles. IC Role / Device Role / Timing Role: Controlled bus gate that asserts high-Z during engine cranking to suppress transients on shared diagnostic lines. Use Value: Dual enable inputs allow synchronized gating of multiple diagnostic channels; 4 µA ICC reduces parasitic drain on vehicle battery. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting 3-state buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT240N | Same logic function, identical AC/DC specs, but TI's DIP-20 has slightly higher max ICC (80 µA vs. 40 µA at 125°C) | Approved for use in TI-designated automotive AEC-Q100 Grade 3 applications; ST part lacks formal AEC qualification | Select SN74HCT240N if AEC-Q100 compliance is mandatory; otherwise M74HCT240B1R offers tighter ICC spec at extended temperature |
| 74HCT240D | NXP SO-20 variant; same electrical behavior but surface-mount only; no DIP option available | Requires PCB redesign for SMT assembly; unsuitable for through-hole prototyping or field-replaceable modules | Choose 74HCT240D only when board space constraints mandate SOIC packaging and reflow capability exists |
Compared with SN74HCT240N and 74HCT240D, M74HCT240B1R uniquely combines DIP-20 through-hole compatibility, lowest high-temp ICC (40 µA), and full –55°C to +125°C characterization - making it optimal for ruggedized industrial retrofits where mechanical serviceability and thermal headroom are critical.
Availability
M74HCT240B1R is available at Aetrix Electronics and suitable for industrial PLC backplanes, telecom line cards, automotive diagnostic interfaces, and legacy system bus isolation requiring stable component supply across extended temperature and long-lifecycle programs.
Supply support for M74HCT240B1R 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.
M74HCT240B1R belongs to the HCT (High-Speed CMOS TTL-compatible) logic family, engineered specifically for seamless integration into legacy 5 V digital systems requiring low power, high noise immunity, and drop-in replacement of 74LS devices.
FAQ
Is M74HCT240B1R pin-compatible with standard 74LS240 devices?
Yes - M74HCT240B1R uses identical pinout and logic function (octal inverting 3-state buffer) as 74LS240, with TTL-compatible input thresholds and CMOS output drive. No PCB changes are needed for direct replacement, though VCC must remain at 4.5–5.5 V.
What is the maximum capacitive load this device can drive reliably?
M74HCT240B1R is characterized up to 150 pF (see AC specs table), with 15 ns tPD at 50 pF and 21 ns at 150 pF. For loads >100 pF, maintain trace length <5 cm and add series termination to avoid ringing; output drive remains ≥6 mA up to 150 pF.
Does this part support hot-swap insertion into a live 5 V bus?
No - while inputs have ESD protection, M74HCT240B1R lacks powered-off protection (Ioff). Applying signals to inputs or outputs while VCC = 0 V may cause latch-up or damage. Always power VCC before asserting any logic signals.
Can both 1G and 2G be tied together for single-enable operation?
Yes - connecting 1G and 2G to a common control signal simplifies design for unified bus gating. This configuration retains full functionality, with all eight outputs enabled or disabled simultaneously, and does not affect timing or drive specifications.
M74HCT240B1R Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- 74HCT
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Logic Type:
- Buffer, Inverting
- Number of Elements:
- 2
- Number of Bits per Element:
- 4
- 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-DIP
M74HCT240B1R FAQ
1.How can I place an order for M74HCT240B1R through Aetrix?
Please submit a Request for Quotation (RFQ) for M74HCT240B1R 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 M74HCT240B1R reliable?
The price and inventory of M74HCT240B1R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M74HCT240B1R is usually 5 days.
3.What payment methods are accepted for M74HCT240B1R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M74HCT240B1R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M74HCT240B1R?
M74HCT240B1R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M74HCT240B1R 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 M74HCT240B1R?
For technical support, including M74HCT240B1R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M74HCT240B1R requirements.
6.How does Aetrix verify that M74HCT240B1R is sourced from the original manufacturer or authorized distributors?
All M74HCT240B1R 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 M74HCT240B1R meets industry standards.
7.What is the process for return or replacement of M74HCT240B1R?
All M74HCT240B1R units undergo pre-shipment inspection (PSI). If there is an issue with M74HCT240B1R, 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 M74HCT240B1R part is unused and in its original packaging.
Return procedure for M74HCT240B1R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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