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Texas Instruments SN74LS145NG4
- Part No.:
- SN74LS145NG4
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74LS145NG4.pdf
- Description:
- IC DECODER 1 X 4:10 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,797
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Product details
Overview
SN74LS145NG4 from Texas Instruments is a TTL BCD-to-decimal decoder/driver IC with open-collector outputs, designed for direct interface to lamps, relays, and other high-current loads. It features 16-pin PDIP packaging, operates from 0°C to 70°C, supports 5-V supply, and provides active-low decoded outputs for decimal digits 0–9.
For engineers reviewing the SN74LS145NG4 datasheet, SN74LS145NG4 pinout, SN74LS145NG4 application, or SN74LS145NG4 equivalent, this device is selected for discrete logic decoding in legacy industrial control panels, LED multiplexing systems, and electromechanical driver interfaces where TTL-compatible open-collector drive and BCD input decoding are required.
Technical Context
The SN74LS145NG4 implements a 4-bit BCD (binary-coded decimal) input decoder with ten active-low decimal output lines (Y₀–Y₉). Its internal logic maps valid BCD inputs (0000–1001) to corresponding low-asserted outputs while leaving Y₁₀–Y₁₅ unasserted for invalid codes.
All outputs are open-collector NPN transistors rated for 80 mA sink current per channel, enabling direct connection to LEDs, incandescent lamps, or relay coils without external pull-up resistors when used with appropriate voltage rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | 74LS TTL - ensures compatibility with standard LS-series logic levels and fanout requirements. |
| Supply Voltage | 4.75 V to 5.25 V - mandates stable 5-V rail; operation outside this range risks incorrect decoding or latch-up. |
| Output Type | Open-collector - requires external pull-up for logic-high assertion; enables wired-OR and mixed-voltage interfacing. |
| Sink Current per Output | 80 mA max - supports direct driving of indicator lamps and small solenoids without buffer stages. |
| Propagation Delay | 45 ns typical (at VCC = 5 V, TA = 25°C) - suitable for synchronous decoding in sub-20-MHz control timing paths. |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded systems, not extended or military temperature ranges. |
| Input Compatibility | BCD-coded 4-bit parallel input (A–D) - accepts standard TTL logic levels; undefined behavior for non-BCD inputs (1010–1111). |
Pinout & Package
SN74LS145NG4 is supplied in a 16-pin plastic dual in-line package (PDIP-N), with 0.3-inch body width and standard through-hole mounting footprint. Pin 1 is located at the left end of the top row, identified by a notch or dot marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (A) | BCD Input Bit 0 (LSB) | Accepts TTL-level signal; low = 0, high = 1 for least-significant BCD digit. |
| 2 (B) | BCD Input Bit 1 | Second BCD bit; combined with A, B, C, D defines decimal value 0–9. |
| 3 (C) | BCD Input Bit 2 | Third BCD bit; unused states (1010–1111) yield no asserted output. |
| 4 (D) | BCD Input Bit 3 (MSB) | Most-significant BCD bit; determines tens place in decimal interpretation. |
| 5–14 (Y₀–Y₉) | Active-Low Decimal Outputs | Open-collector outputs; pulled low when corresponding BCD input matches digit (e.g., Y₂ = low for input 0010). |
| 15 (GND) | Ground Reference | Power return path for internal logic and output transistors; must be low-impedance. |
| 16 (VCC) | Positive Supply | 5-V DC supply input; decoupling capacitor (0.1 µF ceramic) required near pin for noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| BCD-to-decimal decoding | Direct mapping of 4-bit BCD inputs to ten discrete active-low outputs - eliminates need for combinational logic gates in digit selection. |
| Open-collector outputs | Enables shared bus configurations and interface to loads operating at voltages up to 30 V - simplifies level-shifting in mixed-supply systems. |
| High sink current capability | 80 mA per output allows direct lamp/relay actuation - reduces bill-of-materials by removing discrete driver transistors. |
| TTL-compatible inputs | Meets standard 74LS input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V) - ensures reliable operation with upstream LS, S, or F series logic. |
| Commercial temperature grade | 0°C to 70°C operation - optimized for cost-sensitive industrial control panels and instrumentation where extended temperature is unnecessary. |
Applications
| LED Display Multiplexing | Relay Bank Addressing |
|---|---|
|
Use Scenario: Driving common-anode 7-segment or dot-matrix LED displays in timekeeping or status indication systems. IC Role / Device Role / Timing Role: BCD decoder providing active-low digit select signals synchronized with segment data latching. Use Value: Eliminates discrete gate arrays; open-collector outputs interface directly to LED anodes via current-limiting resistors. |
Use Scenario: Selecting one of ten relays in programmable logic controllers or test equipment sequencers. IC Role / Device Role / Timing Role: Decoding microcontroller GPIO BCD outputs to assert individual relay coil drivers. Use Value: 80 mA sink capability drives relay coils directly; avoids need for Darlington arrays or MOSFET buffers. |
| Industrial Panel Meters | Legacy Computer I/O Expansion |
|
Use Scenario: Converting binary counter outputs into decimal digit enable signals for analog meter drivers or digital readouts. IC Role / Device Role / Timing Role: Static decoder translating counter state into discrete digit activation for multiplexed display scanning. Use Value: Propagation delay under 45 ns ensures synchronization with 10–20 kHz scan clocks without timing skew. |
Use Scenario: Expanding address space in vintage minicomputer backplanes or retro computing peripherals. IC Role / Device Role / Timing Role: Address decoder selecting one of ten peripheral slots based on lower 4 bits of address bus. Use Value: TTL-compatible inputs match legacy bus signaling; open-collector outputs simplify wired-OR interrupt generation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar BCD-to-decimal decoding applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS42N | Same 16-pin PDIP, but active-high outputs and no open-collector structure - requires external pull-ups for high-side switching. | Not suitable for direct lamp/relay sinking; better for driving TTL inputs or wired-AND logic. | Select SN74LS42N only if active-high outputs and standard totem-pole drive are required. |
| 74HC42PW | CMOS version in TSSOP-16; 2–6 V supply range; 4 mA output drive; higher noise immunity but lower sink current than SN74LS145NG4. | Requires level translation for 5-V TTL systems; unsuitable for direct 80 mA load driving. | Choose 74HC42PW for low-power, wide-supply applications where sink current < 10 mA suffices. |
Compared with SN74LS42N and 74HC42PW, SN74LS145NG4 uniquely combines TTL compatibility, open-collector architecture, and 80 mA per-output sink strength - making it irreplaceable for direct high-current BCD decoding in commercial-grade industrial hardware.
Availability
SN74LS145NG4 is available at Aetrix Electronics and suitable for industrial control panels, LED display subsystems, and legacy system repair requiring stable component supply and long-term obsolescence management.
Supply support for SN74LS145NG4 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 founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74LS145NG4 belongs to TI's legacy 74LS logic family, engineered for robust TTL interoperability and direct load-driving capability in cost-sensitive commercial control systems.
FAQ
What is the maximum sink current per output on the SN74LS145NG4?
The SN74LS145NG4 specifies a maximum continuous sink current of 80 mA per output terminal (Y₀–Y₉) under recommended operating conditions. This rating allows direct interface to incandescent lamps, LEDs with series resistors, and small electromagnetic relays without external buffering. Exceeding this limit risks thermal degradation or output transistor failure in the SN74LS145NG4.
Does the SN74LS145NG4 support invalid BCD inputs like 1010 or 1111?
No - the SN74LS145NG4 is designed exclusively for valid BCD inputs (0000–1001). Inputs representing decimal values 10–15 (1010–1111) produce no active-low output; all Y₀–Y₉ remain high-impedance (open-circuit) unless pulled high externally. This behavior is inherent to the SN74LS145NG4's internal decoding architecture and is documented in TI's official datasheet.
Can the SN74LS145NG4 operate with a 3.3-V supply?
No - the SN74LS145NG4 is a 74LS-family TTL device requiring a nominal 5-V supply (4.75 V to 5.25 V). Operation at 3.3 V falls outside its specified operating range and will result in unreliable logic thresholds, increased propagation delay, or complete functional failure. For 3.3-V systems, consider CMOS alternatives such as 74HC42, not the SN74LS145NG4.
Is the SN74LS145NG4 RoHS compliant?
Yes - the SN74LS145NG4 carries "Yes" in the RoHS column of TI's official packaging documentation, indicating lead-free terminations (NIPDAU finish) and compliance with EU Directive 2011/65/EU. This applies specifically to the NG4 suffix variant, confirming full environmental compliance for commercial PCB assembly.
What package type does the SN74LS145NG4 use?
The SN74LS145NG4 uses a 16-pin plastic dual in-line package (PDIP-N) with 0.3-inch width, through-hole mounting, and industry-standard pin spacing (0.1 inch). The "NG4" suffix denotes this specific RoHS-compliant PDIP variant, distinct from ceramic DIP (J), LCCC (FK), or SOIC (D) versions of the same logic function.
SN74LS145NG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LS
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Discontinued at Digi-Key
- Type:
- Decoder
- Circuit:
- 1 x 4:10
- Independent Circuits:
- 1
- Current - Output High, Low:
- -, 80mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.75V ~ 5.25V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
SN74LS145NG4 FAQ
1.How can I place an order for SN74LS145NG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS145NG4 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 SN74LS145NG4 reliable?
The price and inventory of SN74LS145NG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS145NG4 is usually 5 days.
3.What payment methods are accepted for SN74LS145NG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS145NG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS145NG4?
SN74LS145NG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS145NG4 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 SN74LS145NG4?
For technical support, including SN74LS145NG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS145NG4 requirements.
6.How does Aetrix verify that SN74LS145NG4 is sourced from the original manufacturer or authorized distributors?
All SN74LS145NG4 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 SN74LS145NG4 meets industry standards.
7.What is the process for return or replacement of SN74LS145NG4?
All SN74LS145NG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS145NG4, 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 SN74LS145NG4 part is unused and in its original packaging.
Return procedure for SN74LS145NG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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