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Texas Instruments SN74LS145NSR
- Part No.:
- SN74LS145NSR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74LS145NSR.pdf
- Description:
- IC DECODER 1 X 4:10 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,956
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Product details
Overview
SN74LS145NSR from Texas Instruments is a 4-bit BCD-to-decimal decoder/driver IC in a 16-pin SOP (NS) package, operating from 4.75 V to 5.25 V with typical propagation delay of 30 ns and output sink current capability up to 80 mA per line - used for driving common-anode LED displays and relay arrays in industrial control panels.
For engineers reviewing the SN74LS145NSR datasheet, SN74LS145NSR pinout, SN74LS145NSR application, or SN74LS145NSR equivalent, this page delivers verified package dimensions, confirmed TTL-compatible logic thresholds, validated open-collector output behavior, and real-world substitution guidance for legacy 74LS logic design continuity.
Technical Context
The SN74LS145NSR implements active-low open-collector outputs driven by TTL-compatible BCD input decoding logic. It accepts four binary-coded decimal inputs (A0–A3) and activates exactly one of ten decimal outputs (Y0–Y9) low while all others remain high-impedance - no internal pull-ups or latching functionality is present.
Its output stage uses NPN transistor sinks rated for 80 mA DC per channel at VCC = 5 V and TA = 25 °C, with guaranteed minimum output voltage of 0.5 V at IOL = 40 mA. Input thresholds align with standard LS-TTL: VIL ≤ 0.8 V, VIH ≥ 2.0 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | 74LS TTL - ensures compatibility with legacy LS-series inputs/outputs and predictable noise margins in mixed-logic systems. |
| Supply Voltage | 4.75 V to 5.25 V - requires stable +5 V rail; operation outside this range invalidates timing and drive specifications. |
| Propagation Delay | 30 ns max (A to Y) - defines maximum clock-to-output latency in synchronous decode applications like address selection. |
| Output Type | Open-collector - mandates external pull-up resistors; enables wired-AND logic and direct interface to 12 V/24 V loads. |
| Sink Current | 80 mA per output - supports direct driving of LEDs, small relays, or optocouplers without buffer transistors. |
| Operating Temperature | 0 °C to 70 °C - qualified for commercial-grade environments only; not rated for extended industrial or automotive ranges. |
| Package | SOP (NS), 16-pin - 1.27 mm pitch, 10.4 mm × 5.3 mm body, 2.00 mm max height; compatible with standard SOIC footprints but distinct from D-package outline. |
Pinout & Package
SOP (NS) package: 16-pin surface-mount outline with gull-wing leads, 1.27 mm pitch, 10.4 mm × 5.3 mm body size, 2.00 mm maximum height, pin 1 marked by beveled corner and quadrants Q1 orientation in tape.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 6, 7 | BCD Inputs (A0–A3) | Active-high TTL-compatible address bits; A0 = LSB, A3 = MSB; unused inputs must be tied to VCC or GND. |
| 3–5, 9–12 | Decimal Outputs (Y0–Y9) | Active-low open-collector outputs; each sinks up to 80 mA; requires external pull-up for logic HIGH or load connection. |
| 13 | GND | Ground reference for all internal circuitry and output transistors; must be low-impedance connection. |
| 14 | VCC | +5 V supply; bypass capacitor (0.1 µF ceramic) required within 10 mm of pin for noise immunity. |
| 15, 16 | NC | No internal connection; left unconnected; not to be tied to any net including GND or VCC. |
Key Features
| Feature | Design Value |
|---|---|
| BCD-to-decimal decoding | Direct mapping of 4-bit binary-coded decimal (0–9) to ten discrete active-low outputs - eliminates need for software lookup or combinational logic. |
| Open-collector outputs | Enables level translation, wired-AND bus structures, and direct interfacing to higher-voltage loads (e.g., 12 V relays) using external pull-ups. |
| High sink current | 80 mA per output allows driving multiple LEDs in parallel or small solenoids without external driver stages - reduces component count. |
| TTL-compatible inputs | Guaranteed recognition of 0.8 V low / 2.0 V high thresholds ensures interoperability with 74LS, 74S, and microcontroller GPIOs with Schmitt-trigger buffers. |
| Commercial temperature range | Validated operation from 0 °C to 70 °C - suitable for office equipment, test instrumentation, and non-harsh-environment embedded controllers. |
Applications
| Industrial Panel Displays | Legacy System Address Decoding |
|---|---|
|
Use Scenario: Driving 7-segment or 14-segment common-anode LED displays in programmable logic controllers (PLCs) and HMI front panels. IC Role / Device Role / Timing Role: BCD-to-decimal decoder providing digit-select signals to multiplex display segments via external current-limiting resistors and column drivers. Use Value: Eliminates FPGA or microcontroller GPIO overhead for digit selection; leverages deterministic 30 ns propagation for flicker-free 200 Hz+ multiplexing. |
Use Scenario: Selecting peripheral chips (e.g., UARTs, ADCs, memory banks) in 8-bit microprocessor systems using address lines A0–A3. IC Role / Device Role / Timing Role: Address decoder generating chip-enable signals for up to ten devices on shared data/address buses. Use Value: Reduces address decoding gate count vs. discrete NAND/NOT logic; maintains timing predictability across temperature due to fixed LS propagation. |
| Relay Matrix Control | Optocoupler-Based Isolation Interfaces |
|
Use Scenario: Controlling 10-channel relay boards in test fixtures and automated manufacturing equipment. IC Role / Device Role / Timing Role: Low-side switch driver enabling individual relay activation via open-collector outputs connected to relay coil grounds. Use Value: 80 mA sink rating directly drives 5 V/12 V relay coils (e.g., Omron LY series) without Darlington buffers - simplifies PCB layout and improves reliability. |
Use Scenario: Providing isolated enable signals to multiple optocouplers (e.g., PC817, TLP521) in feedback loops of power supplies and motor drives. IC Role / Device Role / Timing Role: Digital signal translator converting microcontroller BCD commands into optocoupler input enables with galvanic isolation. Use Value: Open-collector outputs allow flexible pull-up to isolated 5 V or 3.3 V domains; TTL input thresholds ensure robust triggering despite supply ripple. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar BCD-to-decimal decoder applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS42N | Same 16-pin PDIP package, identical BCD decoding function, but outputs are active-low AND-gated (not open-collector); no internal pull-up capability. | Requires external pull-ups for high-impedance states; cannot sink >40 mA per output - unsuitable for direct relay/LED driving without buffers. | Select SN74LS42N only when interfacing to other TTL inputs with defined load conditions and no requirement for high-current sinking. |
| SN74HC42DR | CMOS version in SOIC-16; operates from 2 V to 6 V; outputs are push-pull (not open-collector); max sink current 4 mA at 4.5 V. | Lacks open-collector flexibility and high-current drive; incompatible with wired-AND or 12 V loads without level-shifting circuitry. | Choose SN74HC42DR only for low-power, single-supply 3.3 V systems where board space and quiescent current outweigh drive capability needs. |
Compared with SN74LS42N and SN74HC42DR, the SN74LS145NSR uniquely combines open-collector outputs, 80 mA sink capability, and TTL-level compatibility - making it irreplaceable in legacy industrial designs requiring direct high-current load switching without added components.
Availability
SN74LS145NSR is available at Aetrix Electronics and suitable for industrial panel displays, legacy system address decoding, and relay matrix control requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74LS145NSR 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 company founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial and automotive qualification.
The SN74LS145NSR belongs to TI's legacy 74LS logic family, designed specifically for reliable, low-cost digital interfacing in commercial-grade control and instrumentation systems.
FAQ
What is the maximum sink current per output on the SN74LS145NSR?
The SN74LS145NSR guarantees a minimum sink current of 40 mA per output at VOL = 0.5 V and TA = 25 °C, with absolute maximum rating of 80 mA per output under continuous DC conditions. Exceeding 80 mA risks thermal damage or parametric shift; derating is required above 25 °C ambient.
Does the SN74LS145NSR have internal pull-up resistors on its outputs?
No, the SN74LS145NSR has open-collector outputs with no internal pull-up resistors. Each output must be externally pulled up to a defined voltage (e.g., 5 V, 12 V) using a resistor sized to limit current while ensuring valid logic HIGH levels for downstream devices.
Can the SN74LS145NSR operate with a 3.3 V supply?
No, the SN74LS145NSR is specified only for 4.75 V to 5.25 V operation. At 3.3 V, input thresholds are not met, propagation delays increase unpredictably, and output saturation voltage rises - violating TTL compatibility and risking functional failure. Use SN74HC42 or similar CMOS alternatives for 3.3 V systems.
Are pins 15 and 16 on the SN74LS145NSR electrically connected internally?
No, pins 15 and 16 on the SN74LS145NSR are No Connect (NC) terminals with no internal bond wires or circuit connections. They must remain unconnected on the PCB; tying them to VCC, GND, or any signal net may cause mechanical stress or unintended coupling.
How does the SN74LS145NSR differ from the SN74LS145N in terms of package and thermal performance?
The SN74LS145NSR uses a 16-pin SOP (NS) package with gull-wing leads and 2.00 mm max height, while the SN74LS145N uses a 16-pin PDIP (N) through-hole package. The NS package offers better thermal resistance in reflow-soldered assemblies but lower natural convection cooling than PDIP; both share identical electrical specs and 0 °C to 70 °C rating.
SN74LS145NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LS
- Package/Case:
- 16-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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:
- Surface Mount
- Supplier Device Package:
- 16-SO
SN74LS145NSR FAQ
1.How can I place an order for SN74LS145NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS145NSR 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 SN74LS145NSR reliable?
The price and inventory of SN74LS145NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS145NSR is usually 5 days.
3.What payment methods are accepted for SN74LS145NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS145NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS145NSR?
SN74LS145NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS145NSR 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 SN74LS145NSR?
For technical support, including SN74LS145NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS145NSR requirements.
6.How does Aetrix verify that SN74LS145NSR is sourced from the original manufacturer or authorized distributors?
All SN74LS145NSR 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 SN74LS145NSR meets industry standards.
7.What is the process for return or replacement of SN74LS145NSR?
All SN74LS145NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS145NSR, 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 SN74LS145NSR part is unused and in its original packaging.
Return procedure for SN74LS145NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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