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Texas Instruments SN74HCT240PWT
- Part No.:
- SN74HCT240PWT
- Manufacturer:
- Texas Instruments
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74HCT240PWT.pdf
- Description:
- IC BUFFER INVERT 5.5V 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:648
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Product details
Overview
SN74HCT240PWT from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for memory address and bus driving in industrial and embedded systems. It operates at 4.5V–5.5V, delivers ±6mA output drive per channel at 5V, features 12ns typical propagation delay, and consumes ≤80μA quiescent current. Its dual 4-bit structure with independent OE controls enables selective bus isolation in high-density PCB layouts.
For engineers reviewing the SN74HCT240PWT datasheet, SN74HCT240PWT pinout, SN74HCT240PWT application, or SN74HCT240PWT equivalent, key selection criteria include TTL-compatible input thresholds (VIH = 2V, VIL = 0.8V), 3-state output leakage (≤5μA), thermal resistance (RθJA = 131.8°C/W), and TSSOP-20 package compatibility with IPC-7351 land patterns.
Technical Context
The SN74HCT240PWT implements two independent 4-bit inverting buffers, each controlled by a dedicated output-enable (OE) input. When OE is low, inverted data passes from A inputs to Y outputs; when OE is high, all eight outputs enter high-impedance state-enabling bidirectional bus sharing without contention.
Its HCT logic family ensures TTL-voltage compatibility while maintaining CMOS power efficiency. Input clamp current is ±20mA, absolute max supply voltage is 7V, and it supports CL = 50pF and CL = 150pF load conditions with verified tpd, ten, and tdis timing across –40°C to +85°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5V–5.5V - compatible with standard 5V logic rails and tolerant of ±5% regulation drift |
| Output Drive | ±6mA at 5V - sufficient to drive 15 LSTTL loads directly without external buffering |
| Propagation Delay | 12ns typical (CL = 50pF, VCC = 5.5V) - supports 30+ MHz bus toggle rates in address/data paths |
| Quiescent Current | ≤80μA - enables low-power hold states in battery-backed or energy-sensitive systems |
| Input Leakage | ≤1μA max - prevents unintended logic transitions on unterminated or high-impedance control lines |
| 3-State Leakage | ≤5μA at 5.5V - minimizes bus leakage current during multi-driver contention-free operation |
| Operating Temp | –40°C to +85°C - qualified for industrial ambient environments including motor drives and PLCs |
Pinout & Package
TSSOP-20 (PW) package: 6.50mm × 6.4mm body, 1.2mm max height, 0.65mm pitch, exposed thermal pad recommended per SLMA002/SLMA004.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | OE1, OE2 | Active-low enable inputs - independently disable Group 1 (pins 2–9) or Group 2 (pins 11–18) outputs |
| 2, 4, 6, 8, 11, 13, 15, 17 | A1–A4, A1'–A4' | Inverting data inputs - accept TTL-level signals; drive corresponding Y outputs when OE active |
| 3, 5, 7, 9, 12, 14, 16, 18 | Y1–Y4, Y1'–Y4' | Inverted 3-state outputs - present complemented input data or high-Z state based on OE status |
| 10 | GND | Ground reference - must be low-inductance connection to minimize switching noise coupling |
| 20 | VCC | Power supply - requires local 0.1μF ceramic bypass capacitor placed within 3mm of pin |
Key Features
| Feature | Design Value |
|---|---|
| Inverting 3-state architecture | Enables bus arbitration in shared-memory systems without external direction control logic |
| TTL-compatible inputs | Accepts 0.8V/2.0V thresholds - interoperates with legacy 74LS and microcontroller GPIO without level shifters |
| Low ICC and IOZ | Reduces system standby power and prevents bus loading during inactive periods in multi-drop configurations |
| Controlled edge rates | Typical tt = 11ns (5.5V) - limits EMI generation while ensuring clean signal integrity on 50Ω traces |
| Thermal pad support | Exposed die-pad in TSSOP allows >2× improvement in RθJB vs. non-PowerPAD variants - critical for sustained 8-channel drive |
Applications
| Memory Address Buffering | Industrial Bus Transceiver |
|---|---|
Use Scenario: Driving 16-bit address lines from a microcontroller to multiple SRAM or flash devices on a dense PCB. IC Role / Device Role / Timing Role: Inverting 3-state buffer isolating CPU address bus from peripheral decoders during DMA cycles. Use Value: Prevents address bus contention during simultaneous access; 12ns tpd ensures setup/hold compliance at 25MHz clock domains. | Use Scenario: Bidirectional data routing between an FPGA and multiple I/O expanders over a shared 8-bit parallel bus. IC Role / Device Role / Timing Role: Direction-controlled line driver enabling half-duplex communication without external transceivers. Use Value: Eliminates need for separate TX/RX control logic; ±6mA drive sustains signal integrity across 15cm FR-4 traces. |
| Programmable Logic Interface | Test Equipment Signal Conditioning |
Use Scenario: Interfacing CPLD configuration data lines to legacy 5V peripherals in automated test fixtures. IC Role / Device Role / Timing Role: Level-shifting and fanout buffer for JTAG or boundary-scan control signals. Use Value: TTL-compatible inputs accept open-drain CPLD outputs; 3-state outputs allow dynamic reconfiguration without bus glitches. | Use Scenario: Isolating DUT signal paths from measurement instrumentation in benchtop ATE systems. IC Role / Device Role / Timing Role: Controlled-gain inverting buffer with selectable enable for signal path gating. Use Value: High-Z state blocks leakage into sensitive analog front-ends; 80μA ICC enables always-on monitoring modes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT240PWR | Same silicon, TSSOP-20 tape-and-reel (2000 pcs) vs. SN74HCT240PWT's obsolete tube packaging | Identical electrical specs and pinout - suitable for new designs requiring volume procurement | Select SN74HCT240PWR for production builds; PWT is discontinued and not recommended for new designs |
| SN74ACT240PW | ACT family: higher speed (tpd = 9ns), wider VCC range (4.5V–5.5V), but higher ICC (200μA) | Better for high-frequency timing-critical paths; less suitable for ultra-low-power standby | Choose ACT variant only if 3ns tpd reduction justifies 2.5× higher quiescent current in target application |
Compared with SN74HCT240PWR and SN74ACT240PW, the SN74HCT240PWT offers identical functionality in obsolete packaging-making it viable only for legacy repair, while SN74HCT240PWR provides drop-in replacement capability and SN74ACT240PW trades power for speed in demanding timing environments.
Availability
SN74HCT240PWT is available at Aetrix Electronics and suitable for industrial control, test equipment, and legacy system repair requiring stable component supply and long-term obsolescence management.
Supply support for SN74HCT240PWT 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 50 years of industrial-grade reliability validation.
The SN74HCT240PWT belongs to TI's 74HCT logic family-designed specifically for high-density, low-power 3-state bus interfacing in memory, clock, and control subsystems of industrial and automotive electronics.
FAQ
What is the operating temperature range for SN74HCT240PWT?
The SN74HCT240PWT is rated for operation from –40°C to +85°C, meeting industrial temperature requirements. This range is validated per TI's characterization testing and applies to all electrical specifications in the datasheet, including propagation delay, output drive, and 3-state leakage. The TSSOP-20 package's thermal resistance (RθJA = 131.8°C/W) supports reliable operation within this envelope under typical PCB copper pour conditions.
Does SN74HCT240PWT support TTL-level input signals?
Yes, SN74HCT240PWT features TTL-voltage compatible inputs with VIH = 2.0V (min) and VIL = 0.8V (max) at VCC = 4.5V–5.5V. This allows direct interface with legacy 74LS, 74F, and microcontroller GPIO without level-shifting circuitry. Input current remains ≤1μA across the full common-mode range, preventing loading of upstream drivers.
What is the maximum capacitive load SN74HCT240PWT can drive reliably?
The SN74HCT240PWT is characterized for CL = 50pF and CL = 150pF loads. At 5.5V VCC and 25°C, tpd increases from 12ns (50pF) to 19ns (150pF); ten and tdis scale similarly. For robust design, keep total net capacitance-including trace, via, and receiver input-below 150pF when operating near 25MHz bus frequencies to maintain timing margins.
Is SN74HCT240PWT pin-compatible with other 74HCT240 variants?
Yes, SN74HCT240PWT shares identical pinout and function mapping with all 74HCT240 variants in TSSOP-20 (PW) packaging, including SN74HCT240PWR. Pin assignments for OE, A, Y, VCC, and GND are standardized across TI's HCT240 family. However, SN74HCT240PWT is obsolete; SN74HCT240PWR is the recommended active replacement with identical pinout and electrical behavior.
How should the thermal pad on SN74HCT240PWT be handled in PCB layout?
The SN74HCT240PWT's TSSOP package includes an exposed thermal pad that must be soldered to a PCB copper pour for optimal thermal performance. TI recommends following SLMA002 guidelines: use non-solder-mask-defined (NSMD) pads, fill thermal vias with conductive epoxy or solder, and connect the pad to internal ground planes. This reduces RθJB by ~30%, critical for sustained 8-channel drive at ambient temperatures above 60°C.
SN74HCT240PWT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 20-TSSOP (0.173", 4.40mm 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:
- 6mA, 6mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP
SN74HCT240PWT FAQ
1.How can I place an order for SN74HCT240PWT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCT240PWT 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 SN74HCT240PWT reliable?
The price and inventory of SN74HCT240PWT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCT240PWT is usually 5 days.
3.What payment methods are accepted for SN74HCT240PWT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HCT240PWT transactions.
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4.How is shipping managed for SN74HCT240PWT?
SN74HCT240PWT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCT240PWT 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 SN74HCT240PWT?
For technical support, including SN74HCT240PWT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCT240PWT requirements.
6.How does Aetrix verify that SN74HCT240PWT is sourced from the original manufacturer or authorized distributors?
All SN74HCT240PWT 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 SN74HCT240PWT meets industry standards.
7.What is the process for return or replacement of SN74HCT240PWT?
All SN74HCT240PWT units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCT240PWT, 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 SN74HCT240PWT part is unused and in its original packaging.
Return procedure for SN74HCT240PWT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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