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Texas Instruments SN74HC540NG4
- Part No.:
- SN74HC540NG4
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74HC540NG4.pdf
- Description:
- IC BUFFER INVERT 6V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,245
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Product details
Overview
SN74HC540NG4 from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for bus interface and data routing in digital systems. It operates from 2 V to 6 V, delivers ±6 mA output drive at 5 V, exhibits typical propagation delay of 8 ns, and features low ICC (80 μA max), enabling use in low-power industrial control and legacy TTL-compatible logic interfacing.
For engineers reviewing the SN74HC540NG4 datasheet, SN74HC540NG4 pinout, SN74HC540NG4 application, or SN74HC540NG4 equivalent, key selection considerations include its inverted output logic, dual 3-state enable (OE1/OE2) architecture, data flow-through pinout for PCB layout optimization, and compatibility with LSTTL loads (up to 15 units).
Technical Context
The SN74HC540NG4 implements eight independent inverting buffers, each with high-impedance (3-state) output control via a dual-input NOR gate (OE1 and OE2). When either enable input is high, all outputs enter high-Z mode-no partial enable capability exists.
Its CMOS design ensures rail-to-rail output swing, input thresholds referenced to VCC (VIH = 0.7×VCC, VIL = 0.3×VCC), and robust noise immunity. The data flow-through pinout places all eight inputs on one side and all eight outputs on the opposite side of the 20-pin PDIP package, minimizing trace crossovers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2 V to 6 V - supports mixed-voltage system interfacing and battery-powered operation down to 2 V. |
| Output Drive (5 V) | ±6 mA - sufficient to directly drive 15 LSTTL loads without external buffering. |
| Propagation Delay (tpd) | 8 ns typical at VCC = 4.5 V, CL = 50 pF - enables reliable operation in 25 MHz+ bus timing budgets. |
| Quiescent Current (ICC) | 80 μA max at VCC = 6 V - minimizes standby power in always-on control modules. |
| Input Leakage Current | 1 μA max - ensures stable logic levels even with high-impedance pull-ups or long traces. |
| 3-State Enable Logic | NOR gate (OE1 + OE2) - simplifies system-level bus arbitration with active-low or OR'd enable signals. |
| Output Polarity | Inverted - matches standard 'HC240-series behavior for drop-in replacement in existing designs. |
Pinout & Package
SN74HC540NG4 is supplied in a 20-pin plastic dual in-line package (PDIP-N), with nominal body size 25.40 mm × 6.35 mm and 2.54 mm lead pitch. The package features through-hole mounting and RoHS-compliant NiPdAu lead finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | Inputs A1–A8 | Active-high data inputs; inverted at corresponding outputs Y1–Y8. |
| 9, 10 | Output Enables OE1, OE2 | NOR logic: either high forces all eight outputs into high-impedance state. |
| 11, 13, 14, 15, 16, 17, 18, 20 | Outputs Y1–Y8 | Inverted buffered outputs; 3-state capable; drive bus lines directly. |
| 12 | GND | Ground reference for all internal circuitry and I/O. |
| 19 | VCC | Positive supply rail (2–6 V); requires local 0.1-μF bypass capacitor. |
Key Features
| Feature | Design Value |
|---|---|
| Wide supply voltage range | 2 V to 6 V enables interoperability across 3.3 V and 5 V domains without level shifters. |
| Data flow-through pinout | Inputs (pins 1–8) and outputs (pins 11,13–20) on opposite sides reduce PCB layer count and signal crosstalk. |
| High-current 3-state outputs | ±6 mA drive at 5 V supports direct connection to legacy TTL buses and eliminates need for discrete drivers. |
| Low power consumption | 80 μA max ICC allows integration into power-sensitive applications like remote sensors and portable test equipment. |
| CMOS input characteristics | 1 μA max input current prevents loading of upstream logic and enables long trace routing without signal degradation. |
Applications
| Industrial Bus Interface | Legacy System Upgrade |
|---|---|
|
Use Scenario: Isolating microcontroller GPIOs from noisy 24 V PLC backplanes using optocoupler-driven address/data buses. IC Role / Device Role / Timing Role: Inverting buffer with 3-state control acts as bidirectional bus transceiver during write cycles and high-Z isolator during read/idle states. Use Value: ±6 mA drive ensures clean signal edges across 15-cm ribbon cables; 8 ns tpd maintains timing margin in 10 MHz synchronous protocols. |
Use Scenario: Replacing obsolete 74LS240 in aging test instrumentation requiring TTL-compatible drive strength and HC-speed performance. IC Role / Device Role / Timing Role: Pin-compatible octal inverting buffer providing identical logic function while reducing power by >90% versus LS technology. Use Value: 80 μA ICC eliminates thermal derating concerns in densely packed chassis; 2–6 V operation supports both 5 V legacy rails and modern 3.3 V controllers. |
| Microcontroller Peripheral Expansion | LED Matrix Row Driver |
|
Use Scenario: Expanding limited GPIO count of ARM Cortex-M0+ MCU to drive 8-channel analog multiplexer control lines in medical sensor front-ends. IC Role / Device Role / Timing Role: Level-shifting and fan-out buffer translating 3.3 V MCU outputs to 5 V analog switch control, with OE pins synchronized to ADC conversion windows. Use Value: Rail-to-rail CMOS outputs guarantee full 0–5 V swing; low input current prevents MCU pin loading during sleep modes. |
Use Scenario: Driving common-anode rows of 8×8 LED matrix in consumer audio visualizers, where brightness control is achieved via PWM on OE inputs. IC Role / Device Role / Timing Role: High-current inverting driver sinking up to 6 mA per row; dual OE inputs allow interleaved row blanking to eliminate ghosting. Use Value: 3-state capability enables time-multiplexed scanning without external FETs; 8 ns propagation ensures precise PWM edge alignment across all rows. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT540N | TTL-compatible input thresholds (VIH = 2 V min), otherwise identical pinout, drive, and timing. | Better suited for mixed 5 V TTL/CMOS systems where upstream logic lacks HC-level VIH/VIL margins. | Select SN74HCT540N when interfacing with 74LS or 74F series devices; SN74HC540NG4 preferred for pure CMOS domains. |
| 74AC540PC | Faster tpd (5.5 ns typ at 5 V), higher ICC (40 mA max), and wider VCC range (2–6 V same), but no PDIP-G4 variant available. | Used where sub-6 ns timing is critical and power budget allows higher quiescent draw. | Choose 74AC540PC only if speed gain justifies increased power and sourcing complexity; SN74HC540NG4 remains optimal for cost-sensitive, low-power PDIP designs. |
Compared with SN74HCT540N and 74AC540PC, SN74HC540NG4 provides the best balance of low power, wide supply tolerance, and legacy PDIP availability-making it ideal for industrial control upgrades and long-lifecycle embedded systems where thermal management and component obsolescence are primary concerns.
Availability
SN74HC540NG4 is available at Aetrix Electronics and suitable for industrial bus interface, legacy system upgrade, microcontroller peripheral expansion, and LED matrix row driving requiring stable component supply and long-term manufacturability.
Supply support for SN74HC540NG4 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 SN74HC540NG4 belongs to TI's industry-standard 74HC logic family, engineered for reliable, low-power digital interfacing in harsh environments-designed specifically to replace TTL devices while maintaining pin compatibility and improving efficiency.
FAQ
What logic function does the SN74HC540NG4 implement?
The SN74HC540NG4 implements eight independent inverting buffers, each with 3-state output control. Its functional truth table shows that when both OE1 and OE2 are low, output Yn equals NOT(An); if either OE input is high, Yn enters high-impedance state. This behavior is confirmed in Section 7.3 of the TI SCLS007F datasheet and matches the 'HC240-series architecture.
Is SN74HC540NG4 pin-compatible with SN74HC240N?
No, SN74HC540NG4 is not pin-compatible with SN74HC240N. While both are octal inverting buffers with 3-state outputs, SN74HC240N uses non-inverting outputs and different enable logic (active-high OE). SN74HC540NG4 has inverted outputs and dual active-low NOR-enable inputs (OE1/OE2), resulting in distinct pin assignments-verified in TI's pin configuration diagrams for both devices.
What is the maximum capacitive load SN74HC540NG4 can drive reliably?
SN74HC540NG4 is characterized for CL = 50 pF and CL = 150 pF in its switching specifications. At VCC = 4.5 V and TA = 25 °C, tpd remains within 30 ns (max) and tt within 15 ns (max) at 150 pF. For reliable operation beyond 150 pF, external series termination or reduced slew rate may be required-TI recommends limiting total trace + load capacitance to ≤150 pF for guaranteed timing compliance.
Does SN74HC540NG4 require external pull-up or pull-down resistors on unused inputs?
Yes, all unused inputs of SN74HC540NG4 must be tied to VCC or GND. Floating CMOS inputs cause undefined output states and increased ICC due to shoot-through current. TI's application report SCBA004 explicitly mandates this practice. For SN74HC540NG4, unused A inputs should connect to GND (to force low output) or VCC (to force high output), and unused OE pins must be held low to avoid unintended high-Z activation.
What is the thermal resistance (RθJA) of SN74HC540NG4 in its PDIP package?
The junction-to-ambient thermal resistance (RθJA) for SN74HC540NG4 in the PDIP (N) package is 84.6 °C/W, as specified in Section 5.3 of the TI SCLS007F datasheet (Revision F, July 2022). This value assumes standard JEDEC 2S2P board conditions and is critical for calculating maximum allowable power dissipation at elevated ambient temperatures.
SN74HC540NG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Discontinued at Digi-Key
- Logic Type:
- Buffer, Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- 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:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74HC540NG4 FAQ
1.How can I place an order for SN74HC540NG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC540NG4 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 SN74HC540NG4 reliable?
The price and inventory of SN74HC540NG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC540NG4 is usually 5 days.
3.What payment methods are accepted for SN74HC540NG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC540NG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC540NG4?
SN74HC540NG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC540NG4 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 SN74HC540NG4?
For technical support, including SN74HC540NG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC540NG4 requirements.
6.How does Aetrix verify that SN74HC540NG4 is sourced from the original manufacturer or authorized distributors?
All SN74HC540NG4 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 SN74HC540NG4 meets industry standards.
7.What is the process for return or replacement of SN74HC540NG4?
All SN74HC540NG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC540NG4, 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 SN74HC540NG4 part is unused and in its original packaging.
Return procedure for SN74HC540NG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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