My Inquiry
My Account
Texas Instruments SN74F240DBR
- Part No.:
- SN74F240DBR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74F240DBR.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,534
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SN74F240DBR from Texas Instruments is an octal noninverting buffer/driver with 3-state outputs, designed for memory address driving and bus interfacing in TTL-based systems. It features two independent 4-bit sections, each with active-low output-enable (OE) control, 5 V supply operation, ±64 mA low-level output drive, and propagation delays as low as 1.2 ns (tPHL). It operates from 0°C to 70°C and is packaged in a 20-pin shrink small-outline (SSOP/DB) package.
For engineers reviewing the SN74F240DBR datasheet, SN74F240DBR pinout, SN74F240DBR application, or SN74F240DBR equivalent, key selection criteria include 3-state bus-driving capability, TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2 V), high sink current (IOL = 64 mA), and SSOP footprint compatibility with legacy 20-pin logic layouts.
Technical Context
The SN74F240DBR implements dual 4-bit noninverting buffer architecture with separate active-low OE inputs per section (1OE and 2OE), enabling independent 3-state control of Y1–Y4 and Y1'–Y4' outputs. Each output transitions to high-impedance when its respective OE is high, supporting bidirectional bus arbitration.
It uses standard F-series TTL circuitry with Schottky-clamped transistors, delivering fast switching (tPLH ≤ 8 ns, tPHL ≤ 5.7 ns at VCC = 4.5–5.5 V, CL = 50 pF) and robust noise immunity (VIK = –1.2 V). Input clamp current (IIK = –18 mA) and output short-circuit tolerance (IOS = –225 mA) are specified for transient protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard 5 V TTL rails; operation outside this range risks damage or undefined behavior. |
| Input Thresholds | VIL = 0.8 V, VIH = 2.0 V - ensures reliable recognition of TTL logic levels across temperature and process variation. |
| Output Drive | IOL = 64 mA (min), IOH = –15 mA (min) - sufficient to drive multiple TTL loads or terminate unterminated bus stubs. |
| Propagation Delay | tPHL = 1.2–5.7 ns, tPLH = 2.2–8 ns - supports high-speed address/data buffering in 20–30 MHz system buses. |
| 3-State Enable Time | tPZL = 3.2–10 ns, tPHZ = 1.2–6.3 ns - determines minimum bus turnaround latency when toggling OE between drivers. |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded and industrial control applications, not extended or military range. |
| Package | 20-pin SSOP (DB) - 0.65 mm pitch, 7.2 mm × 5.3 mm body, <50% PCB area vs. standard SOIC, requiring fine-pitch reflow profile. |
Pinout & Package
The SN74F240DBR is housed in a 20-pin shrink small-outline package (SSOP, TI package code DB), measuring 7.2 mm × 5.3 mm with 0.65 mm lead pitch and 2.65 mm max height. Its pinout supports dual 4-bit buffering with symmetrical I/O grouping and dedicated OE controls.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1OE, 2OE | Active-low output-enable inputs - assert low to enable Y1–Y4 (Pin 1) or Y1'–Y4' (Pin 19); high places outputs in high-Z. |
| 2–5, 11–14 | 1A1–1A4, 2A1–2A4 | Noninverting data inputs - directly connected to upstream address/data lines; TTL-compatible voltage thresholds. |
| 18, 16, 14, 12, 9, 7, 5, 3 | 1Y1–1Y4, 2Y1–2Y4 | 3-state buffered outputs - drive downstream bus segments; sink up to 64 mA each while maintaining VOL ≤ 0.55 V. |
| 10, 20 | GND, VCC | Power terminals - require local 0.1 µF ceramic decoupling at VCC pin; GND must be low-inductance return path for output switching currents. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 4-bit sections | Enables split-bus control - e.g., upper/lower byte addressing without inter-section timing skew or shared enable delay. |
| High-current 3-state outputs | 64 mA sink capability per output allows direct drive of 10+ TTL inputs or termination of 50 Ω transmission lines without external buffers. |
| Low propagation delay | Sub-6 ns tPHL/tPLH enables use in 25+ MHz address latching and synchronous bus cycles without added wait states. |
| SSOP (DB) footprint | Reduces PCB area by >50% vs. SOIC-20 while maintaining pin-for-pin compatibility with other DB-package F-series logic devices. |
| TTL input compatibility | VIL = 0.8 V / VIH = 2.0 V ensures interoperability with legacy 74LS, 74ALS, and microcontroller GPIO without level-shifting. |
Applications
| Memory Address Buffering | Parallel Bus Transceiver Interface |
|---|---|
Use Scenario: Driving 16-bit address bus from microprocessor to multiple memory ICs (e.g., SRAM, EPROM) in a 1980s–1990s embedded controller. IC Role / Device Role / Timing Role: Noninverting 3-state buffer isolating CPU address outputs; enables time-multiplexed access to multiple memory banks via OE gating. Use Value: Eliminates address bus contention during memory bank switching; 64 mA drive ensures full TTL fanout (10+) without signal degradation over 10 cm traces. | Use Scenario: Bidirectional data path between microcontroller and peripheral ASIC in a custom backplane system. IC Role / Device Role / Timing Role: Direction-controlled bus driver - one SN74F240DBR section drives data out, second section receives data in, coordinated via OE signals. Use Value: Enables half-duplex parallel communication using single 8-bit data bus; sub-6 ns delays preserve setup/hold timing margins at 20 MHz clock rates. |
| Legacy System Bus Expansion | TTL-Level Signal Conditioning |
Use Scenario: Adding ISA-compatible expansion slots to a vintage PC motherboard or industrial PLC baseboard. IC Role / Device Role / Timing Role: Address/data bus repeater - buffers and restores signal integrity across long trace runs (>15 cm) between slot connectors and core logic. Use Value: Compensates for capacitive loading and noise pickup on extended bus traces; 3-state capability allows hot-plug detection via OE assertion during slot enumeration. | Use Scenario: Interfacing modern FPGA I/O (3.3 V LVTTL) to legacy 5 V TTL peripherals where level shifters are unavailable. IC Role / Device Role / Timing Role: Passive voltage-tolerant buffer - accepts 3.3 V inputs (within VIH/VIL margin) and drives 5 V TTL loads with full current compliance. Use Value: Provides safe, no-component bridging between voltage domains; eliminates need for discrete resistor networks or dedicated level translators in cost-sensitive retrofits. |
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 |
|---|---|---|---|
| SN74F244DBR | Noninverting octal buffer with identical pinout, timing, and drive strength; differs only in internal section organization (two 4-bit groups vs. one 8-bit group). | No functional difference in bus-driving use cases; same PCB layout and firmware control logic apply. | Select SN74F244DBR if system design already uses 8-bit-wide enable control instead of dual 4-bit OE signals. |
| SN74LS240N | Lower drive (IOL = 24 mA), slower speed (tPLH ≈ 25 ns), PDIP-20 package; TTL-compatible but not F-series Schottky performance. | Suitable only for low-frequency (<5 MHz), low-fanout systems; incompatible with SSOP layout or high-speed timing budgets. | Choose SN74LS240N only for cost-sensitive, non-speed-critical replacements where SSOP assembly is unavailable. |
Compared with SN74F244DBR, the SN74F240DBR offers finer-grained 4-bit section control ideal for split-bus architectures; versus SN74LS240N, it delivers 3× faster switching and 2.7× higher output current - critical for maintaining signal integrity in dense, high-speed legacy designs.
Availability
SN74F240DBR is available at Aetrix Electronics and suitable for memory address buffering, parallel bus interfacing, and legacy system bus expansion requiring stable component supply and long-term obsolescence management.
Supply support for SN74F240DBR 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial, automotive, and communications reach.
The SN74F240DBR belongs to TI's 74F family of fast TTL logic devices, engineered for high-speed, low-power memory and bus interface applications in 1980s–1990s computing and instrumentation systems.
FAQ
What is the maximum output sink current specification for SN74F240DBR?
The SN74F240DBR guarantees a minimum low-level output current (IOL) of 64 mA per output under recommended operating conditions (VCC = 4.5 V, TA = 0°C to 70°C). This rating ensures reliable drive of multiple TTL loads or termination of 50 Ω transmission lines without exceeding VOL = 0.55 V. Exceeding this current continuously may cause thermal stress or parametric shift.
Does SN74F240DBR support 3.3 V logic inputs?
Yes, SN74F240DBR accepts 3.3 V logic inputs reliably: its VIH threshold is 2.0 V (min), and 3.3 V exceeds this by 1.3 V margin. However, it does not translate voltages - outputs remain 5 V TTL levels. For bidirectional 3.3 V ↔ 5 V interfacing, external level-shifting or series resistors may be needed to limit input current if driven above VCC.
What is the pin 1 location and orientation for SN74F240DBR in the DB package?
On the SN74F240DBR SSOP (DB) package, pin 1 is located at the top-left corner of the device body when the marking side faces up and the notch or dot indicator is oriented left. The pin numbering proceeds counterclockwise: pins 1–10 along the top edge, pins 11–20 along the bottom edge. This matches JEDEC MS-013 and TI DW0020A outline standards.
Can SN74F240DBR replace SN74F240N in an existing design?
Yes, SN74F240DBR is functionally identical to SN74F240N and shares the same logic behavior, timing, and electrical specs. However, the DB (SSOP) and N (PDIP) packages differ mechanically: DB uses 0.65 mm pitch and surface-mount soldering, while N uses 2.54 mm pitch and through-hole mounting. PCB layout and assembly process must be updated accordingly.
Is SN74F240DBR RoHS compliant?
Yes, SN74F240DBR is RoHS compliant, as confirmed by TI's packaging documentation. It uses NiPdAu (NIPDAU) lead finish and meets exemption-free RoHS requirements. The part marking "F240" and reel packaging (2000 pcs per large tape-and-reel) align with TI's RoHS-compliant production release for this SSOP variant.
SN74F240DBR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74F
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Logic Type:
- Buffer, Inverting
- Number of Elements:
- 2
- Number of Bits per Element:
- 4
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 15mA, 64mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74F240DBR FAQ
1.How can I place an order for SN74F240DBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74F240DBR 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 SN74F240DBR reliable?
The price and inventory of SN74F240DBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74F240DBR is usually 5 days.
3.What payment methods are accepted for SN74F240DBR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74F240DBR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74F240DBR?
SN74F240DBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74F240DBR 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 SN74F240DBR?
For technical support, including SN74F240DBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74F240DBR requirements.
6.How does Aetrix verify that SN74F240DBR is sourced from the original manufacturer or authorized distributors?
All SN74F240DBR 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 SN74F240DBR meets industry standards.
7.What is the process for return or replacement of SN74F240DBR?
All SN74F240DBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74F240DBR, 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 SN74F240DBR part is unused and in its original packaging.
Return procedure for SN74F240DBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74F240DBR Tags
-
SN74LVC1G17DBVR
Texas Instruments
-
SN74LVC1G07DCKR
Texas Instruments
-
SN74LVC1G17DCKR
Texas Instruments
-
SN74LVC1G07DBVR
Texas Instruments
-
SN74LVC1G125DCKR
Texas Instruments
-
SN74AHCT1G126DBVR
Texas Instruments
-
SN74LVC1G125DBVR
Texas Instruments
-
SN74AHCT1G125DBVR
Texas Instruments
-
SN74LVC2G17DBVR
Texas Instruments
-
SN74LVC2G07DCKR
Texas Instruments
-
SN74LVC1G34DCKR
Texas Instruments
-
SN74LVC2G17DCKR
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
