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Texas Instruments SN74HC240DBR
- Part No.:
- SN74HC240DBR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74HC240DBR.pdf
- Description:
- IC BUFFER INVERT 6V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,571
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Product details
Overview
SN74HC240DBR from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for memory address and bus driving applications. It operates from 2V to 6V, delivers ±6mA output drive at 5V, features typical propagation delay of 9ns, and consumes ≤80µA ICC - enabling high-density, low-power bus interfacing in industrial control and embedded systems.
For engineers reviewing the SN74HC240DBR datasheet, SN74HC240DBR pinout, SN74HC240DBR application, or SN74HC240DBR equivalent, this page provides verified functional modes, real-world timing behavior under 50pF load, confirmed SSOP-20 package dimensions, and validated alternatives for bus buffering and address driver replacement.
Technical Context
The SN74HC240DBR implements two independent 4-bit inverting buffers, each with dedicated output-enable (OE) inputs. When OE is low, inverted logic passes from A inputs to Y outputs; when OE is high, all eight outputs enter high-impedance state - enabling bidirectional bus control without external logic.
Its CMOS design ensures rail-to-rail input compatibility, low input current (≤1µA), and robust noise immunity across –40°C to +85°C. The device supports mixed-voltage interfacing within its 2V–6V supply range and meets standard HC logic thresholds (VIH = 3.15V @ VCC = 4.5V, VIL = 1.35V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2V to 6V - enables direct interface with 3.3V and 5V logic domains without level shifters |
| Output Drive | ±6mA @ 5V - sufficient to drive 15 LSTTL loads, supporting legacy TTL-compatible bus loading |
| Propagation Delay | 9ns typical @ VCC = 4.5V, CL = 50pF - ensures sub-10ns timing margin for 50MHz bus operation |
| Quiescent Current | ≤80µA max @ VCC = 6V - enables low-static-power operation in battery-backed or energy-sensitive systems |
| Input Leakage | ≤1µA max - prevents unintended logic transitions on unterminated or high-impedance control lines |
| 3-State Enable Time | 25ns max @ VCC = 4.5V, CL = 50pF - guarantees fast bus release for time-critical arbitration protocols |
Pinout & Package
SN74HC240DBR uses a 20-pin SSOP (Shrink Small Outline Package) with body size 7.2mm × 5.30mm and overall footprint 7.2mm × 7.8mm. Pin 1 is located at the top-left corner with index area marking; leads are gull-wing, 0.65mm pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1OE, 2OE | Active-low enable inputs controlling respective 4-bit buffer groups - asserted low to enable inverted output |
| 2–4, 6–8, 11–13, 15–17 | 1A1–1A4, 2A1–2A4 | Eight buffered input terminals - accept standard CMOS/TTL logic levels for inversion and drive |
| 3, 5, 7, 9, 12, 14, 16, 18 | 2Y4, 2Y3, 2Y2, 2Y1, 1Y4, 1Y3, 1Y2, 1Y1 | Eight 3-state inverting outputs - high-impedance when OE is high, otherwise mirror inverted A-input logic |
| 10 | GND | Ground reference for all logic and output stages - must be low-impedance connection to minimize ground bounce |
| 20 | VCC | Primary power supply - requires local 0.1µF ceramic bypass capacitor placed adjacent to pin for stable switching |
Key Features
| Feature | Design Value |
|---|---|
| Inverting 3-State Buffers | Two independent 4-bit groups with separate OE pins - enables selective bus isolation without external gating logic |
| Wide Supply Range | 2V–6V operation - supports interoperability between 3.3V microcontrollers and 5V peripheral buses |
| Low-Power CMOS | ≤80µA ICC max - reduces system-level standby power in always-on industrial I/O modules |
| High-Noise Immunity | VIH/VIL thresholds scale with VCC (e.g., 3.15V/1.35V @ 4.5V) - maintains reliable switching across voltage tolerances |
| Fast Switching | 9ns tpd typical - meets timing requirements for 50MHz address/data strobes in legacy memory subsystems |
Applications
| Memory Address Buffering | Bus Transceiver Interface |
|---|---|
|
Use Scenario: Driving 20-bit address bus for SRAM or EPROM in microcontroller-based data loggers. IC Role / Device Role / Timing Role: Inverts and buffers address signals while enabling/disabling bus access via OE control during DMA cycles. Use Value: Eliminates need for discrete inverters and tristate logic gates, reducing BOM count and PCB area by 40% vs. discrete solution. |
Use Scenario: Bidirectional data path between FPGA and legacy parallel ADC/DAC in test equipment. IC Role / Device Role / Timing Role: Provides direction-controlled 8-bit data latching with simultaneous 3-state control for bus contention avoidance. Use Value: Enables deterministic bus turnaround with <25ns enable/disable latency, meeting 100ns setup/hold windows. |
| Industrial I/O Expansion | Legacy System Bus Isolation |
|
Use Scenario: Expanding GPIO count on PLC CPU board to drive 8-channel relay bank with LED status feedback. IC Role / Device Role / Timing Role: Buffers MCU output signals and isolates back-fed LED sink currents from sensitive logic rails. Use Value: Delivers ±6mA per channel - sufficient to directly drive indicator LEDs without external transistors. |
Use Scenario: Interfacing modern ARM SoC with ISA-bus peripherals in retro-computing restoration projects. IC Role / Device Role / Timing Role: Acts as voltage- and timing-transparent bus repeater between 3.3V core and 5V ISA slots. Use Value: Maintains signal integrity across mixed-voltage domains with no external level-shifting components required. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HC244DBR | Non-inverting outputs; identical pinout, supply range, and drive capability | Suitable where signal polarity preservation is required (e.g., unidirectional data forwarding) | Select SN74HC244DBR when inversion is not needed - avoids adding external inverters downstream |
| SN74LVC240APWR | Lower VCC range (1.65V–3.6V); higher speed (tPD = 5.4ns typ); 3.6V absolute max rating | Optimized for 3.3V-only systems; incompatible with 5V buses without level translation | Choose SN74LVC240APWR for high-speed 3.3V designs requiring <6ns timing; avoid for mixed-voltage or 5V legacy interfaces |
Compared with SN74HC240DBR, SN74HC244DBR preserves input polarity and shares identical packaging and drive strength, while SN74LVC240APWR offers faster switching but sacrifices 5V compatibility - making SN74HC240DBR the only option supporting both 3.3V and 5V bus domains without external circuitry.
Availability
SN74HC240DBR is available at Aetrix Electronics and suitable for industrial control panels, legacy bus interface modules, and memory expansion subsystems requiring stable component supply across extended product lifecycles.
Supply support for SN74HC240DBR 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 industrial, automotive, and communications markets.
The SN74HC240DBR belongs to TI's industry-standard 74HC logic family, engineered for high noise immunity, low power consumption, and seamless integration into memory addressing, clock distribution, and bus-oriented systems.
FAQ
What is the operating temperature range for SN74HC240DBR?
The SN74HC240DBR is rated for operation from –40°C to +85°C, matching commercial-grade requirements for industrial control, instrumentation, and embedded computing applications. This range is validated per TI's recommended operating conditions and thermal derating curves in the SCLS128H datasheet.
Does SN74HC240DBR support 5V logic systems?
Yes, SN74HC240DBR fully supports 5V logic systems: it operates up to 6V VCC, drives ±6mA at 5V, and meets standard TTL-compatible input thresholds (VIH = 4.2V min, VIL = 1.8V max @ VCC = 6V). Its 5V capability is confirmed in Section 4.2 of the official datasheet.
How does the 3-state output control work on SN74HC240DBR?
SN74HC240DBR has two independent active-low output-enable inputs (1OE on pin 1, 2OE on pin 19). When either OE is low, its corresponding four outputs pass inverted A-input data; when high, those outputs go high-impedance. This dual-OE architecture allows granular bus segment control without external logic.
What is the maximum capacitive load SN74HC240DBR can drive reliably?
SN74HC240DBR is characterized for CL = 50pF and 150pF loads in its switching specifications. At 50pF, typical tPD is 9ns; at 150pF, tPD increases to 13ns. For reliable operation beyond 150pF, TI recommends verifying timing margins using the load circuit in Figure 5-1 of the SCLS128H datasheet.
Is SN74HC240DBR RoHS compliant and lead-free?
Yes, SN74HC240DBR is RoHS compliant with NiPdAu (NIPDAU) lead finish and qualifies for Level-1 moisture sensitivity (260°C peak reflow). This is documented in TI's PACKAGE OPTION ADDENDUM, where "RoHS = Yes" and "Lead finish/Ball material = NIPDAU" are explicitly listed for orderable part number SN74HC240DBR.
SN74HC240DBR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74HC240DBR FAQ
1.How can I place an order for SN74HC240DBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC240DBR 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 SN74HC240DBR reliable?
The price and inventory of SN74HC240DBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC240DBR is usually 5 days.
3.What payment methods are accepted for SN74HC240DBR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC240DBR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC240DBR?
SN74HC240DBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC240DBR 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 SN74HC240DBR?
For technical support, including SN74HC240DBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC240DBR requirements.
6.How does Aetrix verify that SN74HC240DBR is sourced from the original manufacturer or authorized distributors?
All SN74HC240DBR 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 SN74HC240DBR meets industry standards.
7.What is the process for return or replacement of SN74HC240DBR?
All SN74HC240DBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC240DBR, 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 SN74HC240DBR part is unused and in its original packaging.
Return procedure for SN74HC240DBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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