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STMicroelectronics M74HC240B1R
- Part No.:
- M74HC240B1R
- Manufacturer:
- STMicroelectronics
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
M74HC240B1R.pdf
- Description:
- IC BUFFER INVERT 6V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:915
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Product details
Overview
M74HC240B1R from STMicroelectronics is an advanced high-speed CMOS octal bus buffer with 3-state inverted outputs, designed for memory address driving and bidirectional bus interfacing in industrial control and embedded systems. It features 10 ns typical propagation delay at 6 V, ±6 mA output drive, 2 V to 6 V operating voltage, and dual independent 4-bit enable-controlled buffers.
For engineers reviewing the M74HC240B1R datasheet, M74HC240B1R pinout, M74HC240B1R application, or M74HC240B1R equivalent, key selection criteria include 3-state output timing symmetry, noise immunity (28% VCC), wide supply range compatibility, and DIP-20 package suitability for through-hole prototyping and legacy board replacement.
Technical Context
The M74HC240B1R implements two independent 4-bit non-inverting buffer groups (1Y/2Y), each controlled by a dedicated active-low output enable input (1G, 2G). All inputs include ESD protection diodes and transient voltage clamping.
It operates across -55°C to +125°C with symmetrical tPLH/tPHL propagation delays and matched output impedance (|IOH| = IOL ≥ 6 mA), enabling clean signal integrity in mixed-voltage bus environments where level translation and bus contention avoidance are required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2 V to 6 V - supports direct interface with 3.3 V and 5 V logic families without level shifters |
| tPD (Typ.) | 10 ns at VCC = 6 V - enables high-speed address/data buffering in microcontroller peripheral buses |
| IOL / IOH | ≥ 6 mA - drives standard TTL loads and multiple CMOS inputs under worst-case conditions |
| VNIH / VNIL | 28% VCC min - provides robust noise margin against ground bounce and crosstalk in noisy industrial PCBs |
| ICC (Max) | 4 µA at TA = 25°C - ensures ultra-low static power in battery-backed or always-on control modules |
| Operating Temp | -55°C to +125°C - qualified for extended temperature applications including automotive engine control and industrial PLCs |
Pinout & Package
Package: Plastic DIP-20 (0.300" width), 20-pin through-hole, JEDEC MS-001 compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | Output Enable (1G, 2G) | Active-low control for respective 4-bit buffer groups; enables independent bus arbitration |
| 2,4,6,8 | Data Inputs (1A1–1A4) | Input signals routed to inverted outputs 1Y1–1Y4 when 1G = L |
| 3,5,7,9 | Data Outputs (1Y1–1Y4) | Inverted buffered outputs of 1A1–1A4; high-impedance when 1G = H |
| 11,13,15,17 | Data Inputs (2A1–2A4) | Input signals routed to inverted outputs 2Y1–2Y4 when 2G = L |
| 12,14,16,18 | Data Outputs (2Y1–2Y4) | Inverted buffered outputs of 2A1–2A4; high-impedance when 2G = H |
| 10 | GND | Reference ground for all logic and output stages; must be low-inductance connection |
| 20 | VCC | Positive supply rail; bypassing with 100 nF ceramic capacitor near pin is mandatory for AC stability |
Key Features
| Feature | Design Value |
|---|---|
| 3-State Output Control | Dual independent active-low enables allow time-multiplexed sharing of single data bus between multiple peripherals |
| Symmetrical Propagation Delay | tPLH ≅ tPHL minimizes duty cycle distortion in clocked bus applications such as address latching |
| High Noise Immunity | VIH/VIL thresholds defined at 28% VCC ensure reliable switching despite >200 mV ground bounce on shared return paths |
| ESD Protection | All inputs include integrated diode clamps to VCC and GND, rated to ±2 kV HBM per JEDEC JS-001 |
Applications
| Industrial PLC Backplane Interface | Legacy Microcontroller Address Bus Expansion |
|---|---|
Use Scenario: Interfacing 8-bit microcontrollers to parallel EEPROM or SRAM arrays via shared address/data bus. IC Role / Device Role / Timing Role: Octal 3-state inverted buffer isolates CPU address lines from memory bus during DMA cycles. Use Value: Enables deterministic bus release timing with <23 ns max disable time (tPHZ) at 6 V, preventing address glitches during state transitions. | Use Scenario: Adding external I/O port expansion to 8051-based control systems using 74-series-compatible logic. IC Role / Device Role / Timing Role: Level-translating and buffering address latch outputs to drive multiple peripheral decoders. Use Value: 2–6 V operation allows direct use with both 3.3 V MCU I/O and 5 V peripheral logic without external translators. |
| Automotive Engine Control Module | Test Equipment Signal Routing Matrix |
Use Scenario: Isolating sensor interface logic from main ECU bus during firmware updates or diagnostic mode. IC Role / Device Role / Timing Role: Enabling/disabling analog-to-digital converter address lines under microcontroller software control. Use Value: -55°C to +125°C rating and 4 µA max ICC support cold-cranking and under-hood thermal cycling without leakage-induced errors. | Use Scenario: Constructing reconfigurable signal path routing in automated test fixtures with manual or relay-controlled enable sequencing. IC Role / Device Role / Timing Role: Bidirectional bus gate controlling signal flow between DUT and measurement instruments. Use Value: Dual independent enables (1G/2G) permit staggered activation of two 4-bit channels, reducing simultaneous switching noise during test pattern changes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal 3-state buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HC240N | Same logic function and pinout; TI version has slightly higher ICC (8 µA max) and lower noise immunity (20% VCC) | Approved for commercial temp only (-40°C to +85°C); not rated for extended automotive or industrial ambient | Select when cost sensitivity outweighs extended temperature or noise margin requirements |
| 74VHC240N | Higher speed (tPD = 5.5 ns typ. at 5 V); lower drive (±8 mA); identical DIP-20 footprint | Requires tighter layout due to faster edge rates; more susceptible to crosstalk without proper termination | Select for high-frequency bus applications where propagation delay dominates over noise immunity |
Compared with SN74HC240N and 74VHC240N, the M74HC240B1R offers superior extended-temperature reliability and higher noise immunity-critical for industrial control and automotive under-hood use-while maintaining full pin and functional compatibility with legacy 74-series designs.
Availability
M74HC240B1R is available at Aetrix Electronics and suitable for industrial PLC backplane interfaces, automotive engine control modules, and legacy microcontroller address bus expansion requiring stable component supply and long-term obsolescence management.
Supply support for M74HC240B1R 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, specializing in automotive, industrial, and power management ICs with vertical manufacturing capability and AEC-Q100 qualification expertise.
The M74HC240B1R belongs to ST's legacy HC logic family, engineered for drop-in replacement of obsolete 74LS devices in industrial and automotive systems requiring extended temperature operation and enhanced noise immunity.
FAQ
Is M74HC240B1R compatible with 5 V TTL logic inputs?
Yes. The M74HC240B1R accepts TTL-level inputs across its full 2–6 V supply range: VIH = 3.15 V min at VCC = 4.5 V satisfies standard 5 V TTL high threshold (2.0 V min), and input protection diodes clamp to VCC/GND, preventing damage from 5 V signals even when VCC = 3.3 V.
What is the maximum capacitive load this device can drive reliably?
The M74HC240B1R is characterized up to 150 pF load capacitance in AC specs (tPLH/tPHL tested at CL = 150 pF). With 6 mA drive strength and 10 ns typical delay at 6 V, it reliably drives standard PCB traces plus one 74HC-series input (≈10 pF) per output, or up to four such loads with minor delay increase within datasheet limits.
Does this part support hot insertion or live bus swapping?
No. The M74HC240B1R lacks explicit hot-swap circuitry such as power-up reset, bus-hold, or slew-rate control. Its input protection diodes provide limited transient clamping but do not guarantee safe insertion into powered-backplane environments. External current-limiting resistors and sequencing controls are required for live insertion.
How does the "B1R" suffix differ from other M74HC240 variants?
The "B1R" suffix denotes the plastic DIP-20 package in tube packaging (not tape-and-reel), manufactured under ST's original 2001 process revision. It differs from "M1R" (SO-20) and "TTR" (TSSOP-20) only in package type and moisture sensitivity level-not in electrical specifications, timing, or logic function.
M74HC240B1R Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- 74HC
- 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:
- 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-DIP
M74HC240B1R FAQ
1.How can I place an order for M74HC240B1R through Aetrix?
Please submit a Request for Quotation (RFQ) for M74HC240B1R 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 M74HC240B1R reliable?
The price and inventory of M74HC240B1R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M74HC240B1R is usually 5 days.
3.What payment methods are accepted for M74HC240B1R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M74HC240B1R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M74HC240B1R?
M74HC240B1R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M74HC240B1R 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 M74HC240B1R?
For technical support, including M74HC240B1R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M74HC240B1R requirements.
6.How does Aetrix verify that M74HC240B1R is sourced from the original manufacturer or authorized distributors?
All M74HC240B1R 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 M74HC240B1R meets industry standards.
7.What is the process for return or replacement of M74HC240B1R?
All M74HC240B1R units undergo pre-shipment inspection (PSI). If there is an issue with M74HC240B1R, 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 M74HC240B1R part is unused and in its original packaging.
Return procedure for M74HC240B1R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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