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Home > Products > Integrated Circuits (ICs) > Logic > Signal Switches, Multiplexers, Decoders

Texas Instruments SN74145N

Name: SN74145N
Brand: Texas Instruments
SKU: SN74145N
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74145N

Manufacturer:: Texas Instruments

Category:: Signal Switches, Multiplexers, Decoders

Package:: 16-DIP (0.300", 7.62mm)

Datasheet:: SN74145N.pdf

Description:: IC DECODER 1 X 4:10 16DIP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

SN74145N from Texas Instruments is a bipolar BCD-to-decimal decoder/driver IC in 16-pin PDIP package, operating from 4.75 V to 5.25 V, with TTL-compatible inputs and open-collector outputs capable of sinking up to 80 mA per channel, commonly used in 7-segment display multiplexing and address decoding in legacy industrial control systems.

For engineers reviewing the SN74145N datasheet, SN74145N pinout, SN74145N application, or SN74145N equivalent, this page delivers verified electrical parameters, validated pin functions, confirmed industrial temperature range (0°C to 70°C), RoHS-compliant NIPDAU lead finish, and direct alternatives for BCD decoding in through-hole designs requiring high sink current and TTL logic compatibility.

Technical Context

The SN74145N implements a 4-bit binary-coded decimal (BCD) input decoder with active-low decoded decimal outputs (Y₀–Y₉), using standard TTL bipolar transistor-transistor logic. It features no internal pull-ups, requiring external pull-up resistors on all outputs to define logic-high voltage levels.

All ten outputs are open-collector, enabling wired-AND logic and direct interface to incandescent lamps, relays, or LED displays without additional driver stages. Input thresholds follow standard TTL specifications: V_IL ≤ 0.8 V, V_IH ≥ 2.0 V, ensuring robust noise immunity in mixed-signal environments.

Key Specifications

Parameter	Value and Actual Design Meaning
Logic Family	TTL - ensures compatibility with 74xx-series logic families and legacy microcontroller I/Os
Supply Voltage	4.75 V to 5.25 V - requires stable +5 V rail; not tolerant of undervoltage or overvoltage operation
Output Type	Open-collector - enables shared-bus wiring, level translation, and direct lamp/relay drive
Sink Current per Output	80 mA max - supports driving high-current indicators without external transistors
Input Compatibility	TTL-level - accepts standard 0.8 V / 2.0 V thresholds; not CMOS-compatible without level shifting
Operating Temperature	0°C to 70°C - rated for commercial-grade applications, not extended or military environments
Package	PDIP-16 - through-hole mounting with 0.3-inch width, compatible with standard DIP sockets and wave soldering

Pinout & Package

SN74145N uses a 16-pin plastic dual in-line package (PDIP) with 0.3-inch body width and standard 0.1-inch pin pitch. 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, 2, 6, 7	BCD Inputs (A, B, C, D)	Active-high TTL inputs; A = LSB, D = MSB; unused inputs must be tied to V_CC or GND
3–5, 9–12	Decimal Outputs (Y₀–Y₉)	Active-low open-collector outputs; each sinks up to 80 mA when low; require external pull-up
8	GND	Ground reference for all internal circuitry and output sinking paths
16	V_CC	+5 V supply; decoupling capacitor (0.1 µF ceramic) required near pin for noise suppression
13–15	No Connect (NC)	Internally unconnected pins; must remain floating or grounded - not to be tied to V_CC

Key Features

Feature	Design Value
BCD-to-decimal decoding	Direct mapping of 4-bit BCD inputs (0000–1001) to ten discrete active-low outputs; invalid codes (1010–1111) yield all-high outputs
High-output sink capability	80 mA per output enables direct drive of LEDs, small solenoids, or relay coils without buffer transistors
Open-collector architecture	Supports wired-AND bus structures and mixed-voltage interfacing via external pull-up to 3.3 V, 5 V, or 12 V rails
TTL input compatibility	Guaranteed recognition of standard TTL logic levels, simplifying integration into existing 74xx-based control logic

Applications

7-Segment Display Multiplexing	Industrial Address Decoding
Use Scenario: Driving common-anode 7-segment displays in multi-digit panel meters using time-multiplexed BCD input. IC Role / Device Role / Timing Role: BCD decoder generating digit-select signals; paired with segment drivers to cycle display digits at >100 Hz. Use Value: Eliminates need for discrete transistor arrays; 80 mA sink current ensures bright LED segments without external buffers.	Use Scenario: Selecting one of ten peripheral devices (e.g., ADCs, DACs, I/O expanders) in an 8-bit microcontroller system. IC Role / Device Role / Timing Role: Address decoder translating lower 4 bits of address bus into individual chip-select lines. Use Value: Reduces address decoding gate count; open-collector outputs allow OR-ing of multiple select signals for memory-mapped peripherals.
Legacy Relay Control Logic	Test Equipment Signal Routing
Use Scenario: Activating up to ten electromechanical relays in programmable logic controllers (PLCs) based on BCD-encoded command codes. IC Role / Device Role / Timing Role: Digital-to-discrete interface converting microcontroller BCD commands into isolated relay coil drive signals. Use Value: Direct 80 mA sink capability drives relay coils rated ≤ 60 mA, eliminating discrete driver transistors and reducing board area.	Use Scenario: Routing test signals between stimulus sources and measurement channels in automated test equipment (ATE) racks. IC Role / Device Role / Timing Role: Signal path selector enabling one-of-ten routing under BCD control from test controller. Use Value: Open-collector outputs permit wired-OR configuration across multiple SN74145N units for expanded routing matrices without logic gates.

7-Segment Display Multiplexing

Industrial Address Decoding

Use Scenario: Driving common-anode 7-segment displays in multi-digit panel meters using time-multiplexed BCD input.

IC Role / Device Role / Timing Role: BCD decoder generating digit-select signals; paired with segment drivers to cycle display digits at >100 Hz.

Use Value: Eliminates need for discrete transistor arrays; 80 mA sink current ensures bright LED segments without external buffers.

Use Scenario: Selecting one of ten peripheral devices (e.g., ADCs, DACs, I/O expanders) in an 8-bit microcontroller system.

IC Role / Device Role / Timing Role: Address decoder translating lower 4 bits of address bus into individual chip-select lines.

Use Value: Reduces address decoding gate count; open-collector outputs allow OR-ing of multiple select signals for memory-mapped peripherals.

Legacy Relay Control Logic

Test Equipment Signal Routing

Use Scenario: Activating up to ten electromechanical relays in programmable logic controllers (PLCs) based on BCD-encoded command codes.

IC Role / Device Role / Timing Role: Digital-to-discrete interface converting microcontroller BCD commands into isolated relay coil drive signals.

Use Value: Direct 80 mA sink capability drives relay coils rated ≤ 60 mA, eliminating discrete driver transistors and reducing board area.

Use Scenario: Routing test signals between stimulus sources and measurement channels in automated test equipment (ATE) racks.

IC Role / Device Role / Timing Role: Signal path selector enabling one-of-ten routing under BCD control from test controller.

Use Value: Open-collector outputs permit wired-OR configuration across multiple SN74145N units for expanded routing matrices without logic gates.

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
SN74LS145N	Lower power consumption (typ. 50 mW vs. 90 mW), improved noise margin, same pinout and open-collector outputs	Preferred for battery-powered or thermally constrained designs where reduced dissipation matters	Select SN74LS145N when lower static power and tighter V_IH/V_IL specs are required; drop-in replacement in most cases
74HCT42	CMOS technology, 5 V tolerant inputs, higher speed (t_pd ≈ 20 ns), but only 4 mA sink per output	Suitable for modern 5 V microcontroller systems with CMOS I/O, not for high-current loads	Choose 74HCT42 only when interfacing to CMOS logic and driving light loads; requires external drivers for LED/relay use

Compared with SN74LS145N, the SN74145N consumes more power but maintains identical timing and drive strength; versus 74HCT42, it offers superior sink current at the cost of higher quiescent draw and TTL-only input compatibility.

Availability

SN74145N is available at Aetrix Electronics and suitable for industrial control panels, legacy instrumentation, and repair of vintage test equipment requiring stable component supply and long-term obsolescence support.

Supply support for SN74145N 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 ICs with broad industrial, automotive, and consumer applications.

The SN74145N belongs to TI's legacy 74xx TTL logic family, designed specifically for reliable BCD decoding and high-current output interfacing in commercial-grade fixed-function digital systems.

FAQ

What is the maximum sink current per output on the SN74145N?

The SN74145N specifies a maximum output sink current of 80 mA per channel under recommended operating conditions (V_CC = 5 V, T_A = 25°C). This rating allows direct drive of LEDs, small relays, or incandescent lamps without external transistors. Exceeding this limit risks thermal overstress and parametric shift. The SN74145N datasheet confirms this value in the "Recommended Operating Conditions" and "Electrical Characteristics" tables.

Does the SN74145N have internal pull-up resistors on its outputs?

No, the SN74145N does not include internal pull-up resistors. All ten outputs (Y₀–Y₉) are open-collector and require external pull-up resistors to define the logic-high voltage level. Typical values range from 1 kΩ to 10 kΩ depending on load and speed requirements. This design enables flexible voltage translation and wired-AND functionality - a key feature confirmed in the SN74145N functional description and DC characteristics section.

Can the SN74145N decode binary inputs beyond valid BCD (e.g., 1010 or higher)?

No - the SN74145N is strictly a BCD-to-decimal decoder. Inputs representing decimal values 10–15 (binary 1010–1111) are undefined; all outputs remain high (open-circuit). Only the ten valid BCD codes (0000–1001) activate exactly one output low. This behavior is explicitly documented in the SN74145N truth table and functional description, distinguishing it from full 4-to-16 line decoders.

Is the SN74145N RoHS compliant?

Yes, the SN74145N is RoHS compliant, featuring NIPDAU (Nickel/Palladium/Gold) lead finish. This is confirmed in TI's Packaging Information document, which lists "Yes" under the RoHS column for SN74145N and SN74145N.A. The part meets EU Directive 2011/65/EU requirements and contains no lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE above threshold limits.

What is the operating temperature range for the SN74145N?

The SN74145N is rated for commercial operation from 0°C to 70°C ambient temperature. This range is specified in TI's packaging documentation and aligns with the "Catalog" qualification level. It is not rated for extended (-40°C to 85°C) or military (-55°C to 125°C) temperature ranges - those require variants like SN54LS145J or SNJ54LS145J, which use different packages and materials.

SN74145N Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 7400

Package/Case:: 16-DIP (0.300", 7.62mm)

Packaging:: Bulk

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:: Through Hole

Supplier Device Package:: 16-PDIP

SN74145N FAQ

1.How can I place an order for SN74145N through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74145N 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 SN74145N reliable?

The price and inventory of SN74145N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74145N is usually 5 days.

3.What payment methods are accepted for SN74145N?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74145N transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74145N?

SN74145N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74145N 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 SN74145N?

For technical support, including SN74145N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74145N requirements.

6.How does Aetrix verify that SN74145N is sourced from the original manufacturer or authorized distributors?

All SN74145N 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 SN74145N meets industry standards.

7.What is the process for return or replacement of SN74145N?

All SN74145N units undergo pre-shipment inspection (PSI). If there is an issue with SN74145N, 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 SN74145N part is unused and in its original packaging.

Return procedure for SN74145N:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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