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onsemi 74AC240SC
- Part No.:
- 74AC240SC
- Manufacturer:
- onsemi
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
74AC240SC.pdf
- Description:
- IC BUFF INVERT 6V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,984
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Product details
Overview
74AC240SC from onsemi is an octal inverting buffer/line driver with 3-state outputs, designed for memory address driving, bus-oriented transmission/reception, and clock distribution in high-density PCB layouts. It operates at 2.0–6.0 V supply, delivers ±24 mA output drive, and features low ICC (40 µA max) and IOZ (±2.5 µA max) to reduce system power and bus leakage.
For engineers reviewing the 74AC240SC datasheet, pinout, applications, or equivalent options, key selection criteria include its inverting 3-state logic behavior, SOIC-20W package compatibility, AC-family voltage flexibility (3.3 V/5 V), and verified bus-driving capability in industrial control and memory subsystems.
Technical Context
The 74AC240SC implements eight independent inverting buffers, each with dual 3-state enable inputs (OE1 for outputs O0–O3; OE2 for O4–O7), enabling selective bus isolation. Its AC logic family ensures CMOS-level input thresholds and rail-to-rail output swing across 3.3 V and 5 V operation.
Propagation delays are specified at 1.0–9.5 ns (tPLH/tPHL) and 3-state timing at 1.0–11.5 ns (tPZH/tPLZ) under 50 pF load, supporting high-speed bus toggling. Input edge rate requirements (≥125 mV/ns) ensure reliable switching without false triggering.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | Advanced CMOS (AC), compatible with 3.3 V and 5 V systems |
| Supply Voltage Range | 2.0 V to 6.0 V - supports mixed-voltage board design and legacy 5 V interfaces |
| Output Drive | ±24 mA per output - sufficient to drive 50 pF loads and standard TTL/CMOS fanouts |
| Propagation Delay | 1.0–9.0 ns (VCC = 5.0 V, CL = 50 pF) - enables sub-100 MHz bus operation |
| 3-State Leakage | ±2.5 µA max (TA = −40°C to +85°C) - minimizes bus contention current during high-Z state |
| Input Thresholds | VIH = 2.1 V / VIL = 0.9 V @ VCC = 3.0 V - robust noise margin in 3.3 V environments |
| Quiescent Current | 40 µA max @ VCC = 5.5 V - ultra-low static power for always-on control logic |
Pinout & Package
74AC240SC is housed in a Pb-free SOIC-20W package (Case 751BJ), 7.5 mm × 12.8 mm, 1.27 mm pitch, with standard 300-mil body width and JEDEC MS-013 compliance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | OE1, OE2 | Active-low 3-state enable inputs controlling outputs O0–O3 (OE1) and O4–O7 (OE2) |
| 2–9 | I0–I7 | Inverting data inputs - each drives corresponding output with polarity inversion |
| 11–18 | O0–O7 | Inverting 3-state outputs - high-impedance when respective OE is HIGH |
| 10 | GND | Ground reference for all logic and I/O circuitry |
| 20 | VCC | Positive supply rail (2.0–6.0 V); decoupling required near pin for noise immunity |
Key Features
| Feature | Design Value |
|---|---|
| Inverting 3-state outputs | Enables bidirectional bus arbitration without external direction control logic |
| ±24 mA output sink/source | Drives standard 50 pF loads and ≥10 TTL loads directly, eliminating buffer staging |
| Low ICC and IOZ (50% reduction vs. older families) | Reduces total system standby current and bus leakage in multi-device configurations |
| Pb-free SOIC-20W packaging | Complies with JEDEC J-STD-020B and RoHS; compatible with standard reflow profiles |
| Wide VCC range (2.0–6.0 V) | Supports direct interface between 3.3 V controllers and 5 V peripherals without level shifters |
Applications
| Memory Address Buffering | Industrial Bus Transceiver |
|---|---|
|
Use Scenario: Driving address lines from a microcontroller to multiple SRAM or flash devices on a shared bus. IC Role / Device Role / Timing Role: Inverting octal buffer providing signal integrity, fanout expansion, and 3-state isolation during bus contention. Use Value: Eliminates address skew and capacitive loading issues while enabling dynamic bus release via OE control. |
Use Scenario: Isolating and buffering control signals (e.g., chip select, write enable) across noisy factory-floor CAN or RS-485 subsystems. IC Role / Device Role / Timing Role: Level-shifting and noise-immune signal repeater with fast enable/disable timing for synchronized peripheral access. Use Value: Prevents backfeed between subsystems and maintains timing margins under EMI stress due to <9.5 ns propagation delay. |
| Legacy System Clock Distribution | Programmable Logic Interface |
|
Use Scenario: Distributing inverted clock or strobe signals from a CPLD to multiple synchronous logic blocks in retro-computing or test equipment. IC Role / Device Role / Timing Role: Low-skew, inverting clock driver with 3-state capability for dynamic clock gating. Use Value: Ensures matched rise/fall times and eliminates ground bounce via controlled ±24 mA drive strength. |
Use Scenario: Interfacing FPGA I/O banks (3.3 V LVTTL) to legacy 5 V PLD inputs in reconfigurable control modules. IC Role / Device Role / Timing Role: Voltage-tolerant logic translator and bus isolator with inverting polarity matching. Use Value: Enables seamless 3.3 V ↔ 5 V domain bridging without external resistors or dedicated level shifters. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 74ACT240SCX | TTL-compatible inputs (VIH = 2.0 V, VIL = 0.8 V @ 5 V); otherwise identical AC performance and pinout | Better suited for mixed-logic systems with legacy TTL sources; requires 4.5–5.5 V supply only | Select when interfacing with 5 V TTL gates or microcontrollers lacking CMOS-level output swing |
| SN74LVC240APWR | 3.3 V only (1.65–3.6 V), lower drive (±24 mA), but higher speed (tPD = 5.4 ns typ) and smaller TSSOP-20 package | Optimized for modern low-voltage embedded designs; not 5 V tolerant | Choose for space-constrained 3.3 V-only applications where 5 V compatibility is unnecessary |
Compared with 74ACT240SCX and SN74LVC240APWR, the 74AC240SC offers unique 2.0–6.0 V operation and true CMOS input thresholds-making it the only option supporting both 3.3 V microcontrollers and 5 V peripherals without level translation or supply restriction.
Availability
74AC240SC is available at Aetrix Electronics and suitable for industrial control systems, memory subsystems, and programmable logic interfaces requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for 74AC240SC 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power, analog, sensing, and logic solutions for automotive, industrial, and cloud infrastructure markets.
The 74AC240SC belongs to onsemi's legacy logic portfolio, engineered for high-reliability, wide-supply-range interfacing in industrial and legacy-system upgrades where voltage flexibility and bus integrity are critical.
FAQ
What is the operating voltage range of the 74AC240SC?
The 74AC240SC operates over a supply voltage range of 2.0 V to 6.0 V, making it compatible with both 3.3 V and 5 V logic systems. This wide range allows direct integration into mixed-voltage designs without external level-shifting circuitry, and is validated across −40°C to +85°C ambient temperature per the datasheet's Recommended Operating Conditions table.
Does the 74AC240SC support 3-state output control, and how is it implemented?
Yes, the 74AC240SC provides full 3-state output control via two independent active-low enable inputs: OE1 controls outputs O0–O3, and OE2 controls O4–O7. When either OE is HIGH, the corresponding four outputs enter high-impedance state, allowing shared bus operation without contention. This dual-enable architecture enables granular bus partitioning, as confirmed in the Truth Tables and Pin Description sections of the onsemi datasheet.
What is the maximum output drive capability of the 74AC240SC?
The 74AC240SC delivers ±24 mA per output pin under guaranteed conditions (VOH/VOL measured at IOH/IOL = ±24 mA), as specified in the DC Electrical Characteristics tables for AC devices. This drive strength supports direct connection to 50 pF loads and up to 10 standard TTL inputs, eliminating the need for additional buffer stages in most memory and address-bus applications.
Is the 74AC240SC pin-compatible with the 74ACT240SCX?
Yes, the 74AC240SC and 74ACT240SCX share identical pinout, package (SOIC-20W), and functional block diagram. The only difference lies in input threshold specifications: the ACT version has TTL-compatible inputs (VIH = 2.0 V, VIL = 0.8 V), while the AC version uses CMOS thresholds (VIH = 2.1 V, VIL = 0.9 V @ 3.0 V). Both are drop-in replacements in layout, but logic-level compatibility must be verified per system voltage.
What package type and lead finish does the 74AC240SC use?
The 74AC240SC is supplied in a Pb-free SOIC-20W package (Case 751BJ), with 1.27 mm pitch, 7.5 mm × 12.8 mm body, and JEDEC MS-013 compliance. Its marking includes "AC240" and a Pb-free indicator ("G") per the ordering information and mechanical drawings in the onsemi datasheet, confirming full RoHS and J-STD-020B conformance.
74AC240SC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74AC
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- 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:
- 24mA, 24mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
74AC240SC FAQ
1.How can I place an order for 74AC240SC through Aetrix?
Please submit a Request for Quotation (RFQ) for 74AC240SC 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 74AC240SC reliable?
The price and inventory of 74AC240SC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74AC240SC is usually 5 days.
3.What payment methods are accepted for 74AC240SC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74AC240SC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74AC240SC?
74AC240SC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74AC240SC 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 74AC240SC?
For technical support, including 74AC240SC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74AC240SC requirements.
6.How does Aetrix verify that 74AC240SC is sourced from the original manufacturer or authorized distributors?
All 74AC240SC 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 74AC240SC meets industry standards.
7.What is the process for return or replacement of 74AC240SC?
All 74AC240SC units undergo pre-shipment inspection (PSI). If there is an issue with 74AC240SC, 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 74AC240SC part is unused and in its original packaging.
Return procedure for 74AC240SC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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