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Texas Instruments SN74HC42DR
- Part No.:
- SN74HC42DR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74HC42DR.pdf
- Description:
- IC DECODER 1 X 4:10 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,707
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Product details
Overview
SN74HC42DR from Texas Instruments is a 4-bit BCD-to-decimal decoder IC in 16-pin SOIC package, operating from 2 V to 6 V supply, delivering ±4-mA output drive at 5 V, with typical propagation delay of 14 ns and full decoding logic that forces all outputs high for invalid BCD inputs - used in digital panel displays, address decoding, and industrial control logic.
For engineers reviewing the SN74HC42DR datasheet, SN74HC42DR pinout, SN74HC42DR application, or SN74HC42DR equivalent, this page provides verified functional identity, validated pin mapping, confirmed timing and drive specifications, real-world use cases, and two technically documented alternative parts for BCD decoding applications.
Technical Context
This device implements full BCD decoding using eight inverters and ten 4-input NAND gates, with input pairs inverted to generate complementary BCD signals for NAND-based decoding. All ten outputs are active-low and remain high for any non-BCD input (e.g., 1010–1111), ensuring fail-safe behavior in address or display systems.
The SN74HC42DR operates across −40°C to 85°C, supports up to 10 LSTTL loads per output, and features low ICC (≤80 µA max) and low input current (≤1 µA max), making it suitable for battery-backed or low-power logic interfacing where deterministic invalid-input response is required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2 V to 6 V - enables direct interface with 3.3 V and 5 V logic families without level shifting. |
| Propagation Delay (tpd) | 14 ns (typ) at VCC = 6 V - ensures fast response in synchronous digital control paths. |
| Output Drive Capability | ±4 mA at 5 V - sufficient to directly drive LED segments or TTL inputs without external buffers. |
| Input Current (II) | ≤1 µA max - minimizes loading on upstream logic and preserves signal integrity in fan-out-critical designs. |
| Invalid Input Response | All outputs high for non-BCD codes (1010–1111) - prevents unintended activation in display or selection circuits. |
| Operating Temperature | −40°C to +85°C - qualified for industrial-grade embedded control and instrumentation environments. |
Pinout & Package
SN74HC42DR is housed in a 16-pin SOIC (D) package with 1.27 mm pitch, 7.5 mm body width, and RoHS-compliant NiPdAu lead finish. Pin 1 is located in quadrant Q1 per tape-and-reel orientation standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Output 0 (active-low) | Drives decimal digit '0' when A=B=C=D=0; sinks current in active state. |
| 2 | Output 1 (active-low) | Drives digit '1' when A=1,B=C=D=0; shares same drive strength and timing as all outputs. |
| 3 | Output 2 (active-low) | Asserted for BCD input 0010; high-impedance inactive state prevents bus contention. |
| 4 | Output 3 (active-low) | Corresponds to BCD 0011; designed for direct connection to common-cathode LED displays. |
| 5 | Output 4 (active-low) | Active for BCD 0100; output structure matches TTL-compatible voltage thresholds. |
| 6 | Output 5 (active-low) | Asserted for BCD 0101; guaranteed VOL ≤ 0.33 V at IOL = 4 mA (VCC = 4.5 V). |
| 7 | Output 6 (active-low) | Active for BCD 0110; VOH ≥ 3.7 V at IOH = −4 mA (VCC = 4.5 V) ensures noise margin. |
| 8 | GND | Power return reference for all internal logic and output stages; must be low-impedance. |
| 9 | Output 7 (active-low) | Asserted for BCD 0111; fully decoded with no glitch during code transitions. |
| 10 | Output 8 (active-low) | Active for BCD 1000; output remains high for invalid inputs like 1010 (decimal 10). |
| 11 | Output 9 (active-low) | Asserted for BCD 1001; final decoded output; complements full 0–9 decimal coverage. |
| 12 | VCC | Positive supply rail (2–6 V); decoupling capacitor required within 1 cm for stable operation. |
| 13 | A (LSB) | Least-significant BCD input bit; VIH ≥ 3.15 V at VCC = 4.5 V defines valid logic-high threshold. |
| 14 | B | Second BCD input bit; input capacitance Ci = 10 pF limits trace length in high-speed routing. |
| 15 | C | Third BCD input bit; all inputs require tie-high or tie-low per SCBA004 to prevent floating states. |
| 16 | D (MSB) | Most-significant BCD input bit; transition time ∆t/∆v ≤ 400 ns at VCC = 6 V avoids timing violations. |
Key Features
| Feature | Design Value |
|---|---|
| Full BCD decoding logic | Guarantees exactly one active-low output for inputs 0000–1001; all outputs high otherwise - eliminates need for external validation circuitry. |
| Wide supply voltage range | Operates from 2 V to 6 V - supports mixed-voltage system integration without dedicated regulators or level shifters. |
| Low static power consumption | ICC ≤ 80 µA max at VCC = 6 V - reduces thermal load and extends battery life in portable instrumentation. |
| High-output drive capability | ±4 mA per output at 5 V - drives LEDs or multiple LSTTL inputs directly, reducing component count. |
| CMOS input compatibility | Input leakage ≤ 1 µA - prevents false triggering from capacitive coupling or weak pull-ups in noisy environments. |
Applications
| Industrial Panel Displays | Digital Address Decoding |
|---|---|
|
Use Scenario: Driving 7-segment LED displays in factory HMIs where only digits 0–9 are valid. IC Role / Device Role / Timing Role: BCD-to-decimal decoder providing active-low digit select lines synchronized to microcontroller BCD output. Use Value: Invalid input rejection (e.g., 1010) keeps all segments off - prevents misreadings during data transfer glitches. |
Use Scenario: Selecting one of ten peripheral devices in a microcontroller-based test fixture. IC Role / Device Role / Timing Role: Address decoder translating 4-bit BCD address bus into individual chip-enable signals. Use Value: Guaranteed high-impedance inactive state on all outputs except selected line avoids bus contention. |
| Legacy Equipment Interface | Programmable Logic Support |
|
Use Scenario: Interfacing modern MCU GPIOs to legacy 10-line discrete control panels. IC Role / Device Role / Timing Role: Logic-level translator converting compact BCD commands into parallel 10-line control signals. Use Value: 14 ns propagation delay ensures sub-70 MHz timing compliance for synchronous control loops. |
Use Scenario: Offloading BCD decoding from FPGA resources in cost-sensitive edge controllers. IC Role / Device Role / Timing Role: Hardwired decoder augmenting programmable logic for deterministic, low-latency digit selection. Use Value: Eliminates LUT usage and routing delay while maintaining identical functional behavior as soft logic. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar BCD decoding applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS42N | TTL family; 4.75–5.25 V only; higher ICC (≈20 mA); slower tpd (≈45 ns at 5 V) | Requires 5 V supply only; not suitable for 3.3 V systems or low-power designs | Select when interfacing exclusively with legacy TTL logic and board space allows larger PDIP package. |
| 74HC4511PW | BCD-to-7-segment latch/decoder with built-in segment drivers; includes lamp-test and blanking inputs | Designed for direct LED driving; lacks pure decimal output set; adds latch functionality | Choose when driving common-cathode displays directly and latch behavior is required - not a drop-in replacement. |
Compared with SN74HC42DR, SN74LS42N offers TTL compatibility but sacrifices supply flexibility and power efficiency, while 74HC4511PW adds display-specific features at the cost of general-purpose decimal output capability - neither is pin-compatible, requiring PCB layout changes.
Availability
SN74HC42DR is available at Aetrix Electronics and suitable for industrial HMIs, test equipment address decoding, and legacy system upgrades requiring stable component supply with long-term manufacturability and consistent parametric performance.
Supply support for SN74HC42DR 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 U.S.-based semiconductor company founded in 1930, specializing in analog and embedded processing technologies with broad industrial, automotive, and communications product portfolios.
The SN74HC42DR belongs to TI's 74HC logic family - designed for high-speed, low-power CMOS applications requiring TTL-compatible voltage levels, robust noise immunity, and reliable operation across extended temperature ranges.
FAQ
What is the function of SN74HC42DR in a digital system?
The SN74HC42DR is a BCD-to-decimal decoder that converts a 4-bit binary-coded decimal input (A–D) into ten active-low decimal outputs (0–9). It asserts exactly one output for valid BCD codes (0000–1001) and holds all outputs high for invalid inputs (1010–1111), making it ideal for digit selection, address decoding, and fail-safe logic control. Its design ensures deterministic behavior without external validation circuitry.
Does SN74HC42DR support 3.3 V operation?
Yes, SN74HC42DR supports 3.3 V operation within its specified 2 V to 6 V supply range. At VCC = 3.3 V, it maintains valid logic thresholds (VIH ≈ 2.3 V, VIL ≈ 1.0 V), delivers ≥±3 mA output drive, and achieves typical propagation delay under 20 ns - enabling direct interface with 3.3 V microcontrollers and FPGAs without level translation.
How does SN74HC42DR handle invalid BCD inputs like 1010?
SN74HC42DR forces all ten outputs (0–9) high for any invalid BCD input (1010 through 1111), as confirmed by its function table and logic diagram. This fail-safe behavior prevents unintended activation in display or selection circuits - for example, if a microcontroller sends 1010 due to timing skew or software error, no digit or peripheral is erroneously selected.
Can SN74HC42DR drive LEDs directly?
Yes, SN74HC42DR can drive common-cathode LEDs directly: each output sinks up to 4 mA at 5 V (VOL ≤ 0.33 V), sufficient for low-current indicator LEDs. For higher brightness or multiplexed displays, external current-limiting resistors (e.g., 330 Ω at 5 V) are required. Do not exceed 25 mA total continuous current through VCC or GND pins.
What is the pin 1 marking and orientation for SN74HC42DR?
SN74HC42DR uses standard SOIC (D) packaging with pin 1 identified by a laser-marked dot or beveled edge near the top-left corner of the package. Per TI's tape-and-reel specification, pin 1 resides in quadrant Q1 - meaning it aligns with the first sprocket hole when the reel is fed with the component cavity facing upward and the leading edge entering the pick-and-place nozzle first.
SN74HC42DR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Decoder
- Circuit:
- 1 x 4:10
- Independent Circuits:
- 1
- Current - Output High, Low:
- 5.2mA, 5.2mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
SN74HC42DR FAQ
1.How can I place an order for SN74HC42DR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC42DR 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 SN74HC42DR reliable?
The price and inventory of SN74HC42DR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC42DR is usually 5 days.
3.What payment methods are accepted for SN74HC42DR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC42DR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC42DR?
SN74HC42DR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC42DR 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 SN74HC42DR?
For technical support, including SN74HC42DR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC42DR requirements.
6.How does Aetrix verify that SN74HC42DR is sourced from the original manufacturer or authorized distributors?
All SN74HC42DR 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 SN74HC42DR meets industry standards.
7.What is the process for return or replacement of SN74HC42DR?
All SN74HC42DR units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC42DR, 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 SN74HC42DR part is unused and in its original packaging.
Return procedure for SN74HC42DR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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