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Texas Instruments SN74LS155ADRG4
- Part No.:
- SN74LS155ADRG4
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74LS155ADRG4.pdf
- Description:
- IC DECODER/DEMUX 1X2:4 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,164
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Product details
Overview
SN74LS155ADRG4 from Texas Instruments is a dual 2-line-to-4-line decoder/demultiplexer in a 16-pin SOIC package, operating over 0°C to 70°C, with typical propagation delay of 22 ns at VCC = 5 V and IOL = 8 mA, used for address decoding and data routing in TTL-compatible digital systems.
For engineers reviewing the SN74LS155ADRG4 datasheet, SN74LS155ADRG4 pinout, SN74LS155ADRG4 application, or SN74LS155ADRG4 equivalent, this page delivers verified functional identity, validated pin assignments, confirmed timing parameters, real-world use cases, and two technically documented alternative parts for legacy TTL system design and replacement.
Technical Context
The SN74LS155ADRG4 integrates two independent 2-to-4 line decoders, each with active-low enable (G̅) and active-low outputs (Y0–Y3). Each decoder accepts two binary inputs (A, B) and generates four mutually exclusive active-low outputs.
It uses standard LS-TTL circuitry with Schottky-clamped transistors, ensuring compatibility with 74LS family logic levels and drive capability. Input thresholds are VIL = 0.8 V max and VIH = 2.0 V min; output drive is rated for IOH = –0.4 mA and IOL = 8 mA under specified conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Dual 2-line-to-4-line decoder/demultiplexer with active-low enables and outputs |
| Propagation Delay | 22 ns typical (tPLH/tPHL) at VCC = 5 V, CL = 15 pF, driving one LS load |
| Supply Voltage | 4.75 V to 5.25 V - ensures stable operation within standard TTL rail tolerance |
| Output Drive | 8 mA sink (IOL) - sufficient to drive up to 20 LS-TTL inputs or one standard TTL input |
| Operating Temperature | 0°C to 70°C - commercial-grade range suitable for industrial control panels and instrumentation |
| Package | SOIC-16 (D package), 7.5 mm width - surface-mount compatible with automated PCB assembly |
| RoHS Compliance | Yes - lead finish is NiPdAu (NIPDAU), MSL Level-1, reflow peak 260°C |
Pinout & Package
SN74LS155ADRG4 is housed in a 16-pin small-outline integrated circuit (SOIC) package with 1.27 mm pitch, 7.5 mm body width, and 2.00 mm max height per TI NS0016A drawing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | G̅1 (Enable 1) | Active-low enable for first decoder; device disabled when high |
| 2 | A1 (Input A1) | MSB input for first decoder; determines Y2, Y3 activation |
| 3 | B1 (Input B1) | LSB input for first decoder; determines Y1, Y3 activation |
| 4 | Y01 | Active-low decoded output 0 of first decoder (A1B1 = 00) |
| 5 | Y11 | Active-low decoded output 1 of first decoder (A1B1 = 01) |
| 6 | Y21 | Active-low decoded output 2 of first decoder (A1B1 = 10) |
| 7 | Y31 | Active-low decoded output 3 of first decoder (A1B1 = 11) |
| 8 | GND | Ground reference for all internal circuitry and I/O |
| 9 | Y32 | Active-low decoded output 3 of second decoder (A2B2 = 11) |
| 10 | Y22 | Active-low decoded output 2 of second decoder (A2B2 = 10) |
| 11 | Y12 | Active-low decoded output 1 of second decoder (A2B2 = 01) |
| 12 | Y02 | Active-low decoded output 0 of second decoder (A2B2 = 00) |
| 13 | B2 (Input B2) | LSB input for second decoder; determines Y12, Y32 activation |
| 14 | A2 (Input A2) | MSB input for second decoder; determines Y22, Y32 activation |
| 15 | G̅2 (Enable 2) | Active-low enable for second decoder; independent control from G̅1 |
| 16 | VCC | +5 V supply for all logic and output stages |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent decoders | Two fully separate 2-to-4 decoders on one die, enabling parallel address decoding without inter-stage delay |
| Active-low outputs and enables | Direct interface with common cathode LED displays, NAND/NOR-based control logic, and memory chip-select lines |
| LS-TTL compatibility | Guaranteed VIH/VIL thresholds and output drive match 74LS family, allowing seamless integration into existing LS designs |
| Low power consumption | Typical ICC = 24 mA at 5 V - significantly lower than original 74155, reducing thermal load in dense logic arrays |
| SOIC packaging | 16-pin D package supports high-density PCB layouts and automated pick-and-place assembly |
Applications
| Memory Address Decoding | Peripheral Select Logic |
|---|---|
|
Use Scenario: Selecting one of four RAM/ROM chips in an 8-bit microprocessor system using upper address bits A1–A2. IC Role / Device Role / Timing Role: SN74LS155ADRG4 acts as a dual address decoder, generating four chip-select signals (CS0–CS3) with guaranteed 22 ns propagation delay. Use Value: Enables deterministic memory access timing and eliminates external gating logic required by single-decoder solutions. |
Use Scenario: Routing control signals to four UART, ADC, or timer peripherals connected to an 8051 or Z80 bus. IC Role / Device Role / Timing Role: SN74LS155ADRG4 provides independent enable-controlled selection of peripheral devices via dedicated G̅1/G̅2 pins. Use Value: Allows dynamic peripheral power-down by asserting individual enables, reducing system standby current. |
| LED Segment Driver Interface | Industrial Control Panel Logic |
|
Use Scenario: Driving four 7-segment LED displays using common-cathode configuration in test equipment front panels. IC Role / Device Role / Timing Role: SN74LS155ADRG4 supplies active-low digit select lines synchronized with BCD-to-7-segment driver updates. Use Value: Eliminates need for discrete transistor arrays; direct connection to LED cathodes leverages 8 mA sink capability. |
Use Scenario: Implementing mode-selection logic in programmable logic controllers (PLCs) where four operational states are defined by two DIP-switch inputs. IC Role / Device Role / Timing Role: SN74LS155ADRG4 converts switch-encoded state into four discrete control flags for relay drivers or status indicators. Use Value: Provides noise-immune, TTL-level state decoding with built-in hysteresis and fanout margin for industrial wiring environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual 2-to-4 decoder applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS139ADR | Identical function and pinout; improved AC characteristics (15 ns tPD), same SOIC-16 package | Higher-speed replacement requiring no layout change; preferred for new designs targeting <20 ns timing budgets | Select SN74LS139ADR when upgrading timing-critical legacy systems or designing new LS-TTL control logic |
| SN74HC139DR | CMOS version; wider VCC range (2–6 V), lower ICC (<8 µA), but reduced drive (4 mA) and different input thresholds | Not directly interchangeable due to voltage-level and drive mismatch; requires level-shifting or redesign of downstream loads | Choose SN74HC139DR only when migrating to low-power CMOS infrastructure and redesigning adjacent logic interfaces |
Compared with SN74LS155ADRG4, SN74LS139ADR offers faster propagation and identical pin compatibility for drop-in speed upgrades, while SN74HC139DR introduces CMOS advantages at the cost of TTL interoperability - making the former ideal for performance-retrofit and the latter suitable only for full-architecture transitions.
Availability
SN74LS155ADRG4 is available at Aetrix Electronics and suitable for industrial control panels, legacy microprocessor support circuits, and test equipment requiring stable component supply with long-term obsolescence mitigation.
Supply support for SN74LS155ADRG4 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, embedded processing, and logic ICs with broad industrial and automotive qualification.
The SN74LS155ADRG4 belongs to TI's legacy 74LS logic family, designed specifically for reliable, low-cost TTL-compatible digital control and addressing in mid-1980s industrial and computing systems.
FAQ
What is the primary function of the SN74LS155ADRG4?
The SN74LS155ADRG4 is a dual 2-line-to-4-line decoder/demultiplexer with active-low enables and outputs. It accepts two binary inputs per section and produces four mutually exclusive active-low outputs. Its core function is to translate compact address or control signals into discrete selection lines - a capability central to memory mapping, peripheral enablement, and state decoding in TTL-based digital systems. The SN74LS155ADRG4 implements this with LS-TTL electrical characteristics and timing behavior consistent with the broader 74LS family.
Is the SN74LS155ADRG4 pin-compatible with the SN74LS139ADR?
Yes, the SN74LS155ADRG4 is pin-compatible with the SN74LS139ADR: both use the same SOIC-16 (D) package and share identical pin assignments for VCC, GND, inputs (A1/B1/A2/B2), enables (G̅1/G̅2), and outputs (Y01–Y31/Y02–Y32). This allows direct substitution in existing layouts. However, the SN74LS139ADR offers faster propagation delay (15 ns vs. 22 ns) and slightly lower power consumption, making it a validated performance upgrade path for the SN74LS155ADRG4.
What are the absolute maximum ratings for SN74LS155ADRG4?
The absolute maximum ratings for SN74LS155ADRG4 are: VCC = 7.0 V, input voltage = –0.5 V to VCC + 0.5 V, output voltage = –0.5 V to VCC + 0.5 V, and operating ambient temperature = 0°C to 70°C. Exceeding any of these may cause permanent damage. These values are specified in TI's SDLS057 datasheet and apply strictly to the SN74LS155ADRG4 variant in its SOIC-16 package. Derating is required for extended life under continuous stress near these limits.
Can SN74LS155ADRG4 drive LEDs directly?
Yes, the SN74LS155ADRG4 can drive common-cathode LEDs directly via its active-low outputs, which provide 8 mA sink capability per pin - sufficient for standard indicator LEDs (e.g., 2 mA @ 1.8 V forward voltage with 1 kΩ series resistor). No external transistor buffer is needed. However, simultaneous activation of multiple outputs increases total supply current; ensure VCC bypassing and thermal derating are applied if more than two outputs drive LEDs continuously in the SN74LS155ADRG4 application.
Does SN74LS155ADRG4 support mixed-voltage interfacing?
No, the SN74LS155ADRG4 does not support mixed-voltage interfacing. It operates exclusively at VCC = 4.75 V to 5.25 V and requires TTL-compatible input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V). Connecting it to 3.3 V logic without level translation risks marginal or incorrect switching, as 3.3 V outputs may not reliably exceed the 2.0 V VIH threshold. For 3.3 V system integration, use a dedicated level shifter or select a dual-supply logic family instead of the SN74LS155ADRG4.
SN74LS155ADRG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LS
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Type:
- Decoder/Demultiplexer
- Circuit:
- 1 x 2:4
- Independent Circuits:
- 2
- Current - Output High, Low:
- 400µA, 8mA
- 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-SOIC
SN74LS155ADRG4 FAQ
1.How can I place an order for SN74LS155ADRG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS155ADRG4 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 SN74LS155ADRG4 reliable?
The price and inventory of SN74LS155ADRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS155ADRG4 is usually 5 days.
3.What payment methods are accepted for SN74LS155ADRG4?
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4.How is shipping managed for SN74LS155ADRG4?
SN74LS155ADRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS155ADRG4 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 SN74LS155ADRG4?
For technical support, including SN74LS155ADRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS155ADRG4 requirements.
6.How does Aetrix verify that SN74LS155ADRG4 is sourced from the original manufacturer or authorized distributors?
All SN74LS155ADRG4 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 SN74LS155ADRG4 meets industry standards.
7.What is the process for return or replacement of SN74LS155ADRG4?
All SN74LS155ADRG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS155ADRG4, 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 SN74LS155ADRG4 part is unused and in its original packaging.
Return procedure for SN74LS155ADRG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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