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Texas Instruments SN74AHC240DBRE4
- Part No.:
- SN74AHC240DBRE4
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHC240DBRE4.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,016
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Product details
Overview
SN74AHC240DBRE4 from Texas Instruments is an octal 3-state buffer/driver IC designed for bus-oriented data routing, clock distribution, and memory address driving in high-density digital systems. It features dual 4-bit sections with independent output-enable controls, 5.5V-tolerant inputs, 8mA output drive at 5V, and propagation delay as low as 3.6ns (typical, 5V, CL=15pF). It is used in network switch backplanes and industrial control I/O expansion modules.
For engineers reviewing the SN74AHC240DBRE4 datasheet, SN74AHC240DBRE4 pinout, SN74AHC240DBRE4 application, or SN74AHC240DBRE4 equivalent, key selection criteria include 3-state timing symmetry (tPZH = tPLZ), rail-to-rail input tolerance, thermal resistance (RθJA = 60°C/W in PW package), and compatibility with 2.0–5.5V supply rails across –40°C to +85°C operation.
Technical Context
The SN74AHC240DBRE4 implements two independent 4-bit non-inverting buffer sections, each controlled by a dedicated active-low output-enable (OE) input. Its CMOS AHC logic family delivers balanced rise/fall times, low dynamic power, and noise immunity via hysteresis-free inputs with defined VIH/VIL thresholds across VCC = 2.0–5.5V.
It operates in three functional states per output: driven HIGH (VOH ≥ VCC–0.1V), driven LOW (VOL ≤ 0.1V), or high-impedance (IOZ ≤ ±5µA), with fast enable/disable transitions (tPZH/tPLZ ≤ 8.5ns at 5V). The device supports mixed-voltage interfacing due to 5.5V-tolerant inputs while powered from lower VCC rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2.0 V to 5.5 V - Enables direct interface with 2.5V, 3.3V, and 5V logic domains without level shifters. |
| Propagation Delay (tPLH/tPHL) | 3.6 ns (typical, 5V, CL=15pF) - Supports reliable operation up to ~100 MHz bus frequencies in light-load configurations. |
| Output Drive Strength | ±8 mA (at 5V, VOH/VOL limits met) - Sufficient to drive 10+ LVTTL loads or terminate short PCB traces without external buffers. |
| Input Voltage Tolerance | –0.5 V to 5.5 V - Allows safe connection of 5V signals to 3.3V-powered systems without clamping diodes or resistors. |
| Operating Temperature | –40°C to +85°C - Qualified for industrial-grade embedded applications including programmable logic controllers and motor drives. |
| Quiescent Current (ICC) | 4 µA (typical, 5.5V) - Minimizes standby power in battery-backed or energy-sensitive subsystems. |
| ESD Rating (HBM) | ±2000 V - Meets JEDEC JS-001 Class 2 requirements for robust handling in automated assembly environments. |
Pinout & Package
TSSOP-20 (PW) package: 6.5 mm × 6.4 mm body, 1.2 mm max height, 0.65 mm pitch, RoHS-compliant NiPdAu lead finish, MSL Level-1 (260°C reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE | Active-low output enable (Section 1) | Drives all Y1–Y4 outputs to high-impedance when HIGH; enables bidirectional bus isolation on Section 1. |
| 1A1–1A4 | Inputs (Section 1) | Non-inverting data inputs for first 4-bit buffer group; 5.5V tolerant regardless of VCC. |
| 2Y1–2Y4 | Outputs (Section 2) | Driven outputs for second 4-bit section; sink/source up to ±8 mA at 5V with VOL ≤ 0.36 V. |
| 2OE | Active-low output enable (Section 2) | Independent control of Section 2 outputs; allows staggered enable timing for glitch-free bus handoff. |
| GND (Pin 10) | Ground reference | Primary return path for all I/O and internal logic; must be low-inductance connection to minimize ground bounce. |
| VCC (Pin 20) | Power supply | Single-supply rail (2.0–5.5V); requires local 0.1 µF ceramic bypass capacitor placed within 3 mm. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 4-bit sections | Enables asymmetric bus management - e.g., one section for address lines, the other for data strobes - without inter-section timing coupling. |
| 5.5V-tolerant inputs | Eliminates need for external voltage translators when interfacing legacy 5V peripherals to modern 3.3V microcontrollers. |
| Matched tPZH / tPLZ timing | Ensures symmetrical bus release behavior (≤1 ns skew between enable/disable edges), critical for avoiding metastability in shared-bus arbitration. |
| Low ICC and CPD | Reduces total system power: 4 µA quiescent current + 15 pF dynamic capacitance minimizes switching losses in high-frequency clock fanout. |
| High noise immunity | VIH = 3.85 V / VIL = 1.65 V at VCC = 5.5 V provides >1.5 V noise margin against EMI-induced glitches on control lines. |
Applications
| Industrial PLC Backplane Interface | Automotive Body Control Module I/O Expansion |
|---|---|
Use Scenario: Isolating and buffering I/O signals between a main controller MCU and modular field I/O cards in a DIN-rail mounted PLC chassis. IC Role / Device Role / Timing Role: Acts as a direction-controlled signal repeater for parallel address/data buses, enabling hot-swap capability via controlled OE assertion during card insertion/removal. Use Value: Prevents bus contention during module replacement using independent OE pins, while 8mA drive strength ensures signal integrity over 15 cm backplane traces at 25 MHz. |
Use Scenario: Expanding GPIO count on a CAN-connected BCM to support additional door lock actuators, mirror controls, and ambient lighting drivers. IC Role / Device Role / Timing Role: Buffers low-speed control signals (e.g., window up/down, seat position) from the BCM's 3.3V GPIO to 5V-compatible automotive loads. Use Value: 5.5V-tolerant inputs accept feedback signals from 5V sensors/switches without level-shifting; –40°C to +85°C rating matches under-hood environmental requirements. |
| Network Switch ASIC Support Logic | Medical Diagnostic Equipment Data Acquisition Interface |
Use Scenario: Driving clock and reset signals from a 10G Ethernet PHY ASIC to multiple SerDes lanes and auxiliary logic blocks on a high-speed switch line card. IC Role / Device Role / Timing Role: Functions as a low-skew clock buffer and reset distributor, leveraging matched tPLH/tPHL to maintain <100 ps inter-output skew across all eight outputs. Use Value: 3.6 ns typical propagation delay and 1 ns max skew ensure deterministic timing alignment for multi-lane synchronization in IEEE 802.3ae-compliant designs. |
Use Scenario: Interfacing a 16-bit ADC and FPGA-based signal processor in portable ultrasound equipment where space and power are constrained. IC Role / Device Role / Timing Role: Buffers configuration commands and status bits between the FPGA and analog front-end ICs operating at different voltage domains (1.8V FPGA ↔ 3.3V ADC). Use Value: TSSOP-20 footprint (6.5 × 6.4 mm) saves board area vs SOIC; 4 µA ICC extends battery life in handheld diagnostic tools without sacrificing signal fidelity. |
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 |
|---|---|---|---|
| SN74AHCT240PWRE4 | CMOS TTL-compatible input thresholds (VIH = 2.0 V min at VCC = 4.5 V); otherwise identical pinout, timing, and drive. | Better suited for legacy 5V TTL systems where input logic levels may not meet AHC VIH/VIL specs. | Select when interfacing with older 5V microcontrollers lacking 3.3V-compatible outputs. |
| 74LVC240APW,118 | Lower VCC range (1.65–3.6V), 24mA drive at 3.3V, but only 3.6V input tolerance - not 5.5V tolerant. | Optimized for ultra-low-voltage mobile SoC interfaces; unsuitable for mixed 5V/3.3V signal domains. | Prefer for battery-powered devices with strict <3.6V supply constraints and no 5V signal exposure. |
Compared with SN74AHCT240PWRE4, the SN74AHC240DBRE4 offers superior noise margins in 3.3V systems due to higher VIH/VIL ratios, while the 74LVC240APW,118 trades input voltage tolerance for lower static power and higher drive - making SN74AHC240DBRE4 the optimal choice for industrial mixed-voltage bus isolation.
Availability
SN74AHC240DBRE4 is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive body control modules, and medical diagnostic equipment requiring stable component supply and long-term manufacturability.
Supply support for SN74AHC240DBRE4 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 connectivity technologies, with over 90 years of innovation in industrial, automotive, and communications markets.
The SN74AHC240DBRE4 belongs to TI's AHC logic family, engineered for high-speed, low-power, 3-state bus interface applications in industrial automation and infrastructure equipment where reliability and voltage flexibility are critical.
FAQ
What is the maximum output current per pin for SN74AHC240DBRE4?
The SN74AHC240DBRE4 supports ±8 mA per output pin at VCC = 5 V while maintaining VOH ≥ 3.94 V and VOL ≤ 0.36 V. This rating applies under steady-state DC conditions; transient peak currents may exceed this limit briefly but must remain within absolute maximum ratings (±25 mA continuous, ±75 mA total device).
Does SN74AHC240DBRE4 support 2.5V operation?
Yes, SN74AHC240DBRE4 is fully specified for 2.0 V to 5.5 V operation. At VCC = 2.5 V, it delivers tPLH/tPHL ≤ 23 ns (CL = 15 pF), VIH = 1.7 V min, VIL = 0.8 V max, and IOH/IOL = ±50 µA - making it suitable for low-voltage industrial sensor interfaces and legacy 2.5V ASIC support logic.
Can SN74AHC240DBRE4 be used as a level shifter between 5V and 3.3V logic?
SN74AHC240DBRE4 can translate 5V inputs down to 3.3V logic levels because its inputs tolerate up to 5.5V regardless of VCC. However, it cannot translate 3.3V outputs up to 5V - outputs swing only from GND to VCC. For bidirectional translation, a dedicated level shifter IC is required.
What is the thermal resistance (RθJA) of SN74AHC240DBRE4 in its TSSOP package?
The SN74AHC240DBRE4 in the PW (TSSOP-20) package has a junction-to-ambient thermal resistance (RθJA) of 60°C/W under standard JEDEC test conditions (1-layer board, 1 in² copper). This value assumes proper PCB layout with thermal vias and adequate copper pour to dissipate heat during sustained 8mA output loading.
How should unused inputs be handled on SN74AHC240DBRE4?
All unused inputs on SN74AHC240DBRE4 must be tied to a valid logic level - either VCC or GND - to prevent floating states that cause excessive ICC, oscillation, or ESD susceptibility. TI recommends connecting unused A-inputs directly to GND or VCC using short traces; never leave them open, even if the corresponding OE is inactive.
SN74AHC240DBRE4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHC
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 8mA, 8mA
- Voltage - Supply:
- 2V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74AHC240DBRE4 FAQ
1.How can I place an order for SN74AHC240DBRE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHC240DBRE4 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 SN74AHC240DBRE4 reliable?
The price and inventory of SN74AHC240DBRE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHC240DBRE4 is usually 5 days.
3.What payment methods are accepted for SN74AHC240DBRE4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHC240DBRE4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHC240DBRE4?
SN74AHC240DBRE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHC240DBRE4 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 SN74AHC240DBRE4?
For technical support, including SN74AHC240DBRE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHC240DBRE4 requirements.
6.How does Aetrix verify that SN74AHC240DBRE4 is sourced from the original manufacturer or authorized distributors?
All SN74AHC240DBRE4 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 SN74AHC240DBRE4 meets industry standards.
7.What is the process for return or replacement of SN74AHC240DBRE4?
All SN74AHC240DBRE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHC240DBRE4, 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 SN74AHC240DBRE4 part is unused and in its original packaging.
Return procedure for SN74AHC240DBRE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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