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Texas Instruments SN74ALS158DRG4
- Part No.:
- SN74ALS158DRG4
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74ALS158DRG4.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,726
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Product details
Overview
SN74ALS158DRG4 from Texas Instruments is a quad 2-line-to-1-line data selector/multiplexer with inverted output logic, designed for high-speed TTL-compatible digital systems. It features buffered inputs and outputs, 16-pin SOIC (D) package, operates from 4.5 V to 5.5 V, delivers 8 mA low-level output drive, and supports 0°C to 70°C industrial temperature range. It routes one of two 4-bit input sources to four inverted outputs under control of a common strobe (G) and select (A/B) lines.
For engineers reviewing the SN74ALS158DRG4 datasheet, SN74ALS158DRG4 pinout, SN74ALS158DRG4 application, or SN74ALS158DRG4 equivalent, key selection criteria include its inverted-output architecture (vs. true-output SN74ALS157 variants), propagation delay as low as 4 ns (tPHL, A/B→Y), 8 mA sink capability, and compatibility with legacy 74ALS logic families in space-constrained PCB layouts using SOIC packaging.
Technical Context
The SN74ALS158DRG4 implements four independent 2:1 multiplexers sharing a single A/B select line and global strobe (G) enable. Each channel selects between corresponding A and B inputs (1A/1B through 4A/4B) and drives an inverted output (1Y–4Y). Its internal structure includes Schottky-clamped bipolar transistors optimized for speed-power trade-offs typical of Advanced Low-Power Schottky (ALS) technology.
Unlike the SN74ALS157A, this device inverts all outputs-reducing propagation delay by eliminating an external inverter stage in timing-critical paths. The strobe (G) acts as an active-low enable: when high, all outputs are forced low regardless of A/B or data inputs. Input thresholds (VIH = 2 V, VIL = 0.8 V) and output voltage levels (VOH ≥ VCC−2 V, VOL ≤ 0.4 V at IOL = 4 mA) ensure robust noise margins in mixed-logic systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | 74ALS - Advanced Low-Power Schottky TTL, compatible with standard 74LS/74S but with lower power and higher speed. |
| Supply Voltage | 4.5 V to 5.5 V - Operates within standard TTL rail; 5 V nominal ensures interoperability with legacy 5 V digital systems. |
| Output Drive | 8 mA sink (IOL) - Sufficient to directly drive multiple 74ALS/74LS inputs or small LED loads without buffering. |
| Propagation Delay | 4 ns min (tPHL, A/B→Y) - Enables use in sub-25 MHz synchronous data routing applications with tight timing budgets. |
| Operating Temperature | 0°C to 70°C - Qualified for commercial/industrial ambient environments; not rated for extended military or automotive ranges. |
| Input Thresholds | VIH = 2.0 V, VIL = 0.8 V - Provides 0.4 V noise margin at 5 V supply, ensuring reliable switching in electrically noisy board-level environments. |
| Package | SOIC-16 (D), 3.9 mm width - Surface-mount footprint saves board area vs. DIP; RoHS-compliant NiPdAu lead finish. |
Pinout & Package
SN74ALS158DRG4 uses a 16-pin Small-Outline Integrated Circuit (SOIC-D) package with 1.27 mm pitch, 3.9 mm body width, and 1.75 mm height. Pin 1 is marked by a beveled corner or dot; pins are numbered counterclockwise from top-left.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (1B) | Data Input B, Channel 1 | Second 4-bit source input for first multiplexer; tied to system data bus B side. |
| 2 (1A) | Data Input A, Channel 1 | Primary 4-bit source input for first multiplexer; tied to system data bus A side. |
| 3 (2B) | Data Input B, Channel 2 | Second input for second multiplexer; enables parallel 4-bit selection across two channels. |
| 4 (2A) | Data Input A, Channel 2 | Primary input for second multiplexer; used in dual-bus arbitration or register file read paths. |
| 5 (G) | Strobe Enable (Active-Low) | Global enable: high forces all Y outputs low; low enables normal multiplexing operation. |
| 6 (2Y) | Inverted Output, Channel 2 | Complemented result of 2A/2B selection; eliminates need for external inverters in feedback loops. |
| 7 (1Y) | Inverted Output, Channel 1 | Complemented output of 1A/1B selection; used in address/data path inversion or parity generation. |
| 8 (GND) | Ground Reference | Power return path; must be low-impedance connection to minimize ground bounce in high-speed switching. |
| 9 (3A) | Data Input A, Channel 3 | Third multiplexer's primary input; supports 3-channel data routing in microcode sequencers. |
| 10 (3B) | Data Input B, Channel 3 | Third multiplexer's secondary input; used in ALU operand selection or status register muxing. |
| 11 (4A) | Data Input A, Channel 4 | Fourth multiplexer's primary input; commonly connected to instruction register or latch outputs. |
| 12 (4B) | Data Input B, Channel 4 | Fourth multiplexer's secondary input; enables dynamic reconfiguration of control signal paths. |
| 13 (4Y) | Inverted Output, Channel 4 | Final inverted output; routed to clock enable or interrupt mask logic requiring active-low assertion. |
| 14 (3Y) | Inverted Output, Channel 3 | Third inverted output; used in pipeline stage control or conditional execution flag generation. |
| 15 (A/B) | Common Select Line | Single-bit control determining whether A or B inputs pass to all four outputs simultaneously. |
| 16 (VCC) | Positive Supply | +5 V power rail; requires local 0.1 µF ceramic decoupling adjacent to pin to suppress switching noise. |
Key Features
| Feature | Design Value |
|---|---|
| Inverted Output Logic | Eliminates external inverters in critical timing paths, reducing component count and propagation delay by up to 3 ns per stage. |
| Buffered Inputs/Outputs | Enables fan-out of up to 20 74ALS loads without signal degradation, supporting dense bus architectures. |
| Low Power Consumption | ICC = 5–10 mA at VCC = 5.5 V - 30% lower than comparable 74AS devices, easing thermal management in compact assemblies. |
| High Noise Immunity | Guaranteed VIH/VIL margins (2.0 V / 0.8 V) provide >400 mV noise rejection at 5 V, improving reliability in industrial EMI environments. |
| SOIC Packaging | 16-pin D package (7.5 mm × 5.3 mm) reduces PCB area by ~65% vs. PDIP, enabling high-density control logic modules. |
Applications
| Microprocessor Bus Arbitration | Programmable Logic Control |
|---|---|
|
Use Scenario: Selecting between two memory-mapped peripheral data buses during DMA cycles in an 8-bit microcontroller system. IC Role / Device Role / Timing Role: Quad 2:1 data selector routing 4-bit status/control signals from alternate peripherals to CPU data bus with inverted polarity. Use Value: Enables real-time bus switching without software overhead; 4 ns tPHL ensures no cycle penalty during high-frequency peripheral access. |
Use Scenario: Implementing conditional output masking in an industrial PLC I/O module where sensor inputs determine actuator enable states. IC Role / Device Role / Timing Role: Inverting multiplexer generating active-low enable signals for relay drivers based on programmable logic state. Use Value: Directly drives 8 mA relay coils or optocouplers; eliminates discrete inverters and reduces BOM count by four components per IC. |
| Legacy System Emulation | Digital Test Equipment |
|
Use Scenario: Replicating vintage computer address decoding logic (e.g., Apple II, TRS-80) where inverted bus signals are required for ROM/RAM selection. IC Role / Device Role / Timing Role: Providing inverted 4-bit address segment selection to match original TTL-based memory map behavior. Use Value: Maintains bit-for-bit functional equivalence with original hardware; SOIC package allows retrofit into modern PCBs without redesign. |
Use Scenario: Configuring signal routing paths in automated test equipment that validates 4-bit parallel interface timing margins. IC Role / Device Role / Timing Role: Generating precise, inverted stimulus patterns on four channels while synchronizing to a global strobe (G) trigger. Use Value: 5.5 V absolute max rating allows safe margin during test fixture overvoltage conditions; 8 mA drive ensures clean edges into 50 Ω scope inputs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad 2:1 multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS157ADR | Provides true (non-inverted) outputs; identical pinout, timing, and electrical specs otherwise. | Used where downstream logic expects non-inverted data; requires external inverters if inversion is needed. | Select SN74ALS157ADR when system timing budget allows added inverter delay or when matching existing true-output designs. |
| SN74AS158N | Faster propagation (1–4.5 ns vs. 4–15 ns), higher ICC (15.6–22.5 mA), and same inverted output logic. | Suitable for high-speed systems (>30 MHz) but increases power dissipation and heat generation. | Choose SN74AS158N only when sub-5 ns delays are mandatory and thermal design accommodates +10 mA average current increase. |
Compared with SN74ALS157ADR and SN74AS158N, the SN74ALS158DRG4 balances speed, power, and inversion functionality-making it optimal for cost-sensitive, thermally constrained industrial control boards needing guaranteed inverted outputs without layout changes.
Availability
SN74ALS158DRG4 is available at Aetrix Electronics and suitable for industrial control systems, legacy equipment repair, programmable logic modules, and digital test instrumentation requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74ALS158DRG4 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 innovator founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74ALS158DRG4 belongs to TI's legacy 74ALS logic family, engineered for backward compatibility with 74LS systems while delivering improved speed-power efficiency for retro-design refreshes and maintenance of installed base equipment.
FAQ
What is the function of the G (strobe) pin on the SN74ALS158DRG4?
The G pin on the SN74ALS158DRG4 is an active-low strobe enable. When G is high, all four Y outputs are forced low regardless of A/B select or data inputs. When G is low, the device performs normal 2:1 multiplexing with inverted outputs. This allows synchronous gating of all four channels in timing-critical control paths, such as CPU bus enable or interrupt masking. The SN74ALS158DRG4 uses this feature to simplify system-level handshaking without additional logic gates.
Does the SN74ALS158DRG4 support 3.3 V operation?
No, the SN74ALS158DRG4 does not support 3.3 V operation. Its recommended supply range is strictly 4.5 V to 5.5 V, and absolute maximum VCC is 7 V. Input thresholds (VIH = 2.0 V, VIL = 0.8 V) are defined for 5 V TTL compatibility. Driving it from a 3.3 V microcontroller without level translation risks marginal VIH recognition and increased static power consumption due to partial transistor turn-on. For 3.3 V systems, consider modern CMOS alternatives like SN74LVC157A instead of the SN74ALS158DRG4.
How does the SN74ALS158DRG4 differ from the SN74ALS157A in practical circuit design?
The SN74ALS158DRG4 differs from the SN74ALS157A solely in output polarity: SN74ALS158DRG4 provides inverted outputs (1Y–4Y = NOT(A/B)), while SN74ALS157A provides true outputs. Both share identical pinout, timing, drive strength, and power specs. In practice, this means SN74ALS158DRG4 eliminates the need for four external inverters in applications requiring complemented signals-reducing PCB area, component count, and propagation delay by ~3 ns per channel. Use SN74ALS158DRG4 when inversion is inherent to the system logic flow.
Is the SN74ALS158DRG4 pin-compatible with other 16-pin SOIC multiplexers like the SN74HC157?
No, the SN74ALS158DRG4 is not pin-compatible with SN74HC157 or other CMOS multiplexers. Although both are 16-pin SOIC devices, their pin assignments differ: SN74ALS158DRG4 places G on pin 5 and A/B on pin 15, whereas SN74HC157 locates G on pin 1 and A/B on pin 16. Additionally, SN74ALS158DRG4 uses bipolar ALS technology with 5 V-only operation and TTL input thresholds, while SN74HC157 is CMOS with wider voltage range and different logic levels. Interchange requires full schematic and layout revision-not just replacement of the SN74ALS158DRG4.
What is the maximum capacitive load the SN74ALS158DRG4 can drive reliably?
The SN74ALS158DRG4 is characterized for CL = 50 pF in switching specifications, with propagation delays measured under those conditions. While it can drive heavier loads, performance degrades: tPLH/tPHL increase linearly with capacitance, and output voltage margins (VOH/VOL) compress above 50 pF due to limited slew rate. For reliable operation beyond 50 pF-such as driving long traces or multiple loads-add a series resistor (22–47 Ω) near the driver output to dampen ringing and maintain signal integrity. Always verify timing margins in final layout simulation when using the SN74ALS158DRG4 with >50 pF loads.
SN74ALS158DRG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Multiplexer
- Circuit:
- 4 x 2:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- 400µA, 8mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
SN74ALS158DRG4 FAQ
1.How can I place an order for SN74ALS158DRG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS158DRG4 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 SN74ALS158DRG4 reliable?
The price and inventory of SN74ALS158DRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS158DRG4 is usually 5 days.
3.What payment methods are accepted for SN74ALS158DRG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS158DRG4 transactions.
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SN74ALS158DRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS158DRG4 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 SN74ALS158DRG4?
For technical support, including SN74ALS158DRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS158DRG4 requirements.
6.How does Aetrix verify that SN74ALS158DRG4 is sourced from the original manufacturer or authorized distributors?
All SN74ALS158DRG4 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 SN74ALS158DRG4 meets industry standards.
7.What is the process for return or replacement of SN74ALS158DRG4?
All SN74ALS158DRG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS158DRG4, 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 SN74ALS158DRG4 part is unused and in its original packaging.
Return procedure for SN74ALS158DRG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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