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Texas Instruments SN74145NSR
- Part No.:
- SN74145NSR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74145NSR.pdf
- Description:
- IC DECODER 1 X 4:10 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,875
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Product details
Overview
SN74LS145NSR from Texas Instruments is a 4-line-to-10-line 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 25 ns and output sink current capability of 40 mA per line, used in address decoding and seven-segment display driving applications.
For engineers reviewing the SN74LS145NSR datasheet, SN74LS145NSR pinout, SN74LS145NSR application, or SN74LS145NSR equivalent, this device serves as a TTL-compatible BCD decoder with open-collector outputs requiring external pull-ups, supporting direct LED interface and high-voltage logic level translation in industrial control panels and legacy instrumentation systems.
Technical Context
The SN74LS145NSR implements active-low decoded outputs for decimal digits 0–9 based on four binary-coded decimal inputs (A0–A3), with all ten outputs independently driven low when their corresponding BCD code is present. It uses standard TTL bipolar transistor logic with Schottky clamping to suppress saturation delay.
No internal pull-up resistors are integrated; each of the ten output terminals requires an external pull-up resistor to VCC or higher voltage rail. Input thresholds conform to standard LS-TTL levels (VIL ≤ 0.8 V, VIH ≥ 2.0 V), and output leakage current is specified at ≤ 100 µA when high and ≤ 0.4 V at IOL = 40 mA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | LS-TTL - ensures compatibility with legacy 74LS series systems and predictable noise margins. |
| Supply Voltage | 4.75 V to 5.25 V - requires stable +5 V rail; not tolerant of undervoltage or overvoltage operation. |
| Propagation Delay | 25 ns max (tPLH/tPHL) - defines maximum clock rate for synchronous decode timing in address selection circuits. |
| Output Type | Open-collector - enables wired-OR logic, level shifting up to 30 V, and direct LED/anode-driving without series resistors. |
| Sink Current | 40 mA per output - supports driving multiple LEDs or relays directly without buffer transistors. |
| Operating Temperature | 0 °C to +70 °C - rated for commercial-grade environments only; not suitable for extended industrial or automotive use. |
Pinout & Package
SOP (NS) package: 16-pin small-outline package with 1.27 mm pitch, 8.1 mm × 10.4 mm body size, and maximum height of 2.00 mm; RoHS-compliant, NIPDAU lead finish, MSL Level-1 rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 6, 7 | BCD Inputs (A0–A3) | Binary-coded decimal address lines; A0 = LSB, A3 = MSB; active-high logic. |
| 3–5, 9–15 | Decimal Outputs (Y0–Y9) | Active-low open-collector outputs; Y0 asserted when A3–A0 = 0000, Y9 when 1001. |
| 8 | GND | Ground reference for all internal circuitry and output sink paths. |
| 16 | VCC | +5 V supply input; must be decoupled locally with 0.1 µF ceramic capacitor. |
Key Features
| Feature | Design Value |
|---|---|
| BCD-to-decimal decoding | Direct mapping of 4-bit binary input to one of ten mutually exclusive active-low outputs. |
| Open-collector outputs | Enables interface to voltages beyond 5 V (up to 30 V) and supports wired-AND/wired-OR bus architectures. |
| High sink current drive | 40 mA per output allows direct connection to LEDs, small solenoids, or optocoupler inputs without buffering. |
| TTL-compatible inputs | Meets LS-TTL input voltage thresholds, ensuring interoperability with 74LS, 74S, and 74F logic families. |
Applications
| Industrial Control Panels | Legacy Instrumentation Displays |
|---|---|
|
Use Scenario: Decoding microcontroller address bus lines to select discrete indicators or relay drivers in panel-mounted PLC I/O modules. IC Role / Device Role / Timing Role: BCD decoder providing one-hot enable signals for 10-channel output expansion. Use Value: Eliminates need for discrete logic gates or microcontroller firmware overhead by delivering deterministic, hardware-based digit selection. |
Use Scenario: Driving common-anode seven-segment displays via external current-limiting resistors in analog multimeters and oscilloscope front panels. IC Role / Device Role / Timing Role: Decimal output driver converting BCD data from ADC or counter ICs into segment-select logic. Use Value: Provides precise, glitch-free digit activation with sufficient sink current to illuminate segments at full brightness without added transistors. |
| Telecom Line Card Indicators | Test Equipment Channel Selectors |
|
Use Scenario: Activating status LEDs for 10-slot line cards in legacy telecom switching equipment using shared +12 V rail. IC Role / Device Role / Timing Role: Open-collector level translator and decoder enabling single IC to drive LEDs referenced to non-5 V supplies. Use Value: Reduces component count by combining decoding and high-voltage interface functions in one package. |
Use Scenario: Selecting one of ten test signal paths in automated calibration fixtures using manual BCD thumbwheel switches. IC Role / Device Role / Timing Role: Static address decoder generating enable pulses for analog multiplexers or relay matrices. Use Value: Guarantees monotonic output transitions during switch bounce, preventing false channel activation during manual selection. |
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 LS-TTL family, 4-to-10 decoder, but with different pinout (outputs Y0–Y9 on pins 1–10) and no internal NAND gate structure - purely combinational. | Requires PCB layout revision due to incompatible pin mapping; lacks identical output drive strength spec at 40 mA. | Select SN74LS42N only if redesign accommodates pin reassignment and lower guaranteed sink current (32 mA). |
| 74HC42PW | CMOS version with wider supply range (2–6 V), lower power, but only 4 mA sink current and 5 V logic-level compatibility only at VCC = 5 V. | Not drop-in compatible: cannot drive LEDs directly without buffers; susceptible to noise in noisy industrial environments. | Choose 74HC42PW only for battery-powered or low-power designs where drive strength and noise immunity are secondary to quiescent current. |
Compared with SN74LS42N and 74HC42PW, the SN74LS145NSR delivers superior output drive, proven noise margin in legacy systems, and direct open-collector interfacing - making it the preferred choice for robust, high-current BCD decoding where reliability outweighs power savings.
Availability
SN74LS145NSR is available at Aetrix Electronics and suitable for industrial control panels, legacy instrumentation displays, telecom line card indicators, and test equipment channel selectors requiring stable component supply across long-lifecycle programs.
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 ICs with broad industrial, automotive, and communications portfolio coverage.
The SN74LS145NSR belongs to TI's legacy 74LS logic family, designed specifically for reliable, high-drive BCD decoding in commercial-grade systems where compatibility with existing TTL infrastructure is essential.
FAQ
What is the function of SN74LS145NSR in a digital system?
The SN74LS145NSR is a 4-line-to-10-line BCD-to-decimal decoder with open-collector outputs. It converts a 4-bit binary-coded decimal input into one of ten active-low decimal outputs. In systems like industrial control panels or test equipment, the SN74LS145NSR provides deterministic, hardware-based digit selection without firmware involvement, enabling direct LED or relay driving via external pull-ups.
Does SN74LS145NSR require external pull-up resistors on its outputs?
Yes, SN74LS145NSR requires external pull-up resistors on all ten outputs (Y0–Y9) because it features open-collector outputs. Without pull-ups, outputs remain floating when inactive. Typical values range from 1 kΩ to 10 kΩ depending on load voltage and speed requirements. The SN74LS145NSR itself does not integrate any internal pull-up circuitry.
Can SN74LS145NSR operate at 3.3 V supply voltage?
No, SN74LS145NSR is not rated for 3.3 V operation. Its absolute maximum supply voltage is 5.5 V, and minimum recommended VCC is 4.75 V to ensure proper LS-TTL logic thresholds and output drive performance. Operating SN74LS145NSR below 4.75 V risks incorrect decoding, increased propagation delay, and failure to meet output sink specifications.
What is the maximum output sink current specification for SN74LS145NSR?
The SN74LS145NSR guarantees a minimum output sink current of 40 mA per output (Y0–Y9) at VOL ≤ 0.4 V when VCC = 5 V and TA = 25 °C. This allows the SN74LS145NSR to drive LEDs, small relays, or optocouplers directly without additional transistor stages - a key design advantage over lower-drive alternatives.
Is SN74LS145NSR pin-compatible with SN74LS42N?
No, SN74LS145NSR is not pin-compatible with SN74LS42N. Although both are 4-to-10 decoders in 16-pin packages, their pin assignments differ significantly: SN74LS145NSR places inputs on pins 1, 2, 6, 7 and outputs across pins 3–5 and 9–15, while SN74LS42N allocates outputs Y0–Y9 to pins 1–10. Using SN74LS42N as a replacement for SN74LS145NSR requires PCB layout modification.
SN74145NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 7400
- Package/Case:
- 16-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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
SN74145NSR FAQ
1.How can I place an order for SN74145NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74145NSR 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 SN74145NSR reliable?
The price and inventory of SN74145NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74145NSR is usually 5 days.
3.What payment methods are accepted for SN74145NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74145NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74145NSR?
SN74145NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74145NSR 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 SN74145NSR?
For technical support, including SN74145NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74145NSR requirements.
6.How does Aetrix verify that SN74145NSR is sourced from the original manufacturer or authorized distributors?
All SN74145NSR 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 SN74145NSR meets industry standards.
7.What is the process for return or replacement of SN74145NSR?
All SN74145NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74145NSR, 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 SN74145NSR part is unused and in its original packaging.
Return procedure for SN74145NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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