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Texas Instruments SN74AS298AN
- Part No.:
- SN74AS298AN
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74AS298AN.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,968
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Product details
Overview
SN74AS298AN from Texas Instruments is a quadruple 2-input multiplexer with synchronous storage, functioning as a dual 4-bit register/multiplexer in a single 16-pin PDIP package. It selects between two 4-bit data words (A1–D1 or A2–D2) via the WS input and latches the selected word on the negative edge of CLK, delivering outputs QA–QD. It operates across 0°C to 70°C and supports up to 62 MHz clock frequency - used in arithmetic processor operand routing and BCD shift registers.
For engineers reviewing the SN74AS298AN datasheet, SN74AS298AN pinout, SN74AS298AN application, or SN74AS298AN equivalent, this device serves as a high-speed, TTL-compatible register-mux hybrid for deterministic data path control, parallel load capability, and compound shift operations in legacy digital systems.
Technical Context
The SN74AS298AN integrates four independent D-type flip-flops with a 2:1 multiplexer per bit, enabling simultaneous selection and edge-triggered storage. Its architecture supports both synchronous parallel loading and controlled data shifting - with WS determining source word and CLK↓ capturing the selected inputs into QA–QD.
It uses AS (Advanced Schottky) bipolar logic, delivering 2 ns tPLH and 1 ns tPHL propagation delays at CL = 50 pF, while sustaining ±20 mA output drive (IOL) and −2 mA IOH. The device requires VCC = 4.5–5.5 V and exhibits VIH ≥ 2 V and VIL ≤ 0.8 V under recommended operating conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Quadruple 2-input multiplexer with synchronous D-type latch per bit |
| Max Clock Frequency | 62 MHz - enables high-throughput operand switching in ALU pipelines |
| Propagation Delay (tPLH/tPHL) | 2 ns / 1 ns - ensures tight timing margins in 5-V TTL systems |
| Output Drive (IOL/IOH) | 20 mA sink / −2 mA source - directly drives multiple 74AS inputs without buffering |
| Supply Voltage Range | 4.5 V to 5.5 V - compatible with standard 5-V TTL power rails |
| Operating Temperature | 0°C to 70°C - rated for commercial-grade embedded and test equipment use |
| Input Thresholds (VIH/VIL) | ≥2.0 V / ≤0.8 V - ensures noise-immune logic-level recognition in mixed-logic systems |
Pinout & Package
SN74AS298AN is supplied in a 16-pin plastic dual in-line package (PDIP), 300-mil width, with through-hole mounting and industry-standard pin spacing (0.1″). Pin 1 is bottom-left corner when notch faces up.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | B2 | Bit-2 input of second 4-bit word; routed to QB when WS = H |
| 2 | A2 | Bit-1 input of second 4-bit word; routed to QA when WS = H |
| 3 | A1 | Bit-1 input of first 4-bit word; routed to QA when WS = L |
| 4 | B1 | Bit-2 input of first 4-bit word; routed to QB when WS = L |
| 5 | C2 | Bit-3 input of second 4-bit word; routed to QC when WS = H |
| 6 | D2 | Bit-4 input of second 4-bit word; routed to QD when WS = H |
| 7 | D1 | Bit-4 input of first 4-bit word; routed to QD when WS = L |
| 8 | GND | Power ground reference for all internal logic and I/O |
| 9 | VCC | +5 V supply rail; decoupling capacitor required near pin |
| 10 | QA | Registered output of bit-1; reflects A1 or A2 based on WS and CLK↓ |
| 11 | QB | Registered output of bit-2; reflects B1 or B2 based on WS and CLK↓ |
| 12 | QC | Registered output of bit-3; reflects C1 or C2 based on WS and CLK↓ |
| 13 | QD | Registered output of bit-4; reflects D1 or D2 based on WS and CLK↓ |
| 14 | CLK | Clock input; negative-edge triggered latch control for all four bits |
| 15 | WS | Word-select control; L = select Word 1 (A1–D1), H = select Word 2 (A2–D2) |
| 16 | C1 | Bit-3 input of first 4-bit word; routed to QC when WS = L |
Key Features
| Feature | Design Value |
|---|---|
| Integrated MUX + Register per bit | Eliminates need for separate SN74AS157 and SN74AS175A ICs - reduces board space and interconnect count |
| Negative-edge clock capture | Enables precise synchronization with system clocks that assert data before falling edge, improving setup margin |
| Compound left-right shift capability | Supports configurable 1-place or 2-place shifts via WS control - useful in BCD/binary multiplier architectures |
| Parallel load retention | Allows full 4-bit word entry in one CLK cycle regardless of WS state - maintains register flexibility during data acquisition |
| AS-family speed/power balance | Delivers 62 MHz operation with 33 mA max ICC at 5.5 V - optimized for performance-critical 5-V TTL systems |
Applications
| Arithmetic Processor Operand Routing | BCD Digit Shift Register |
|---|---|
|
Use Scenario: Arithmetic logic unit (ALU) requires alternating access to two operand sources - e.g., register file vs. constant ROM - without stalling pipeline execution. IC Role / Device Role / Timing Role: SN74AS298AN acts as a dual-source operand selector and temporary holding register, synchronized to ALU clock domain. Use Value: Frees register file bandwidth by offloading operand staging, enabling concurrent fetch and execute phases in microcoded controllers. |
Use Scenario: Decimal arithmetic unit shifts entire 4-bit BCD digits left/right for multiplication/division or decimal alignment. IC Role / Device Role / Timing Role: SN74AS298AN implements a universal 4-bit shift register where WS controls shift distance (1 or 2 positions) per CLK pulse. Use Value: Achieves multi-digit BCD shift in single-cycle latency - avoids iterative microcode loops and improves decimal computation throughput. |
| ALU-Controlled Multiplier Pipeline | Legacy Test Equipment Data Path |
|
Use Scenario: Hardware multiplier uses iterative partial-product accumulation; intermediate results must be shifted and aligned before addition. IC Role / Device Role / Timing Role: SN74AS298AN provides registered, selectable shift paths for partial products under ALU-generated WS control. Use Value: Enables variable-shift capability (1- or 2-bit) within fixed-clock multiplier stages - reduces iteration count and total latency. |
Use Scenario: Automated test system routes stimulus patterns from multiple sources (pattern RAM, counter, external bus) to DUT interface pins. IC Role / Device Role / Timing Role: SN74AS298AN functions as a programmable 4-bit data switch with latch hold, synchronized to test sequencer clock. Use Value: Guarantees glitch-free pattern delivery during source transitions - critical for deterministic timing in boundary-scan and functional test. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multiplexer-with-storage applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AS157N | Quad 2-input mux only - no internal storage; requires external latch (e.g., SN74AS175N) for registered behavior | Lacks synchronous capture; unsuitable for applications requiring atomic word selection + latch on single edge | Select SN74AS157N only if external clock control and latch timing independence are required |
| SN74AS175N | 4-bit D-type register only - no integrated multiplexer; inputs must be pre-selected externally | Cannot perform on-the-fly source switching; adds routing complexity and propagation delay | Choose SN74AS175N when register depth > 1 or when multiplexing is handled upstream (e.g., FPGA fabric) |
Compared with SN74AS157N and SN74AS175N, the SN74AS298AN uniquely combines selection and storage in one cycle - reducing component count, interconnect delay, and layout area in space-constrained 5-V TTL designs.
Availability
SN74AS298AN is available at Aetrix Electronics and suitable for arithmetic processor operand routing, BCD digit shifting, ALU-controlled multiplier pipelines, and legacy test equipment data path applications requiring stable component supply and long-term obsolescence management.
Supply support for SN74AS298AN 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 SN74AS298AN belongs to TI's Advanced Schottky (AS) TTL logic family - engineered for high-speed, low-noise 5-V digital systems where timing precision and drive strength are critical.
FAQ
What is the primary function of the SN74AS298AN?
The SN74AS298AN is a quadruple 2-input multiplexer with synchronous D-type storage. It selects between two 4-bit input words (A1–D1 or A2–D2) using the WS input and latches the chosen word onto QA–QD outputs on the negative edge of CLK. This dual functionality replaces discrete mux and register ICs in compact 5-V TTL designs.
Does the SN74AS298AN support 3.3-V operation?
No, the SN74AS298AN is specified only for 4.5 V to 5.5 V supply operation and is not 3.3-V tolerant. Its input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) and output voltage levels (VOH ≈ VCC−2 V, VOL ≤ 0.5 V) are designed for 5-V TTL compatibility. Interfacing with 3.3-V systems requires level-shifting circuitry.
How does the word-select (WS) input affect SN74AS298AN behavior?
When WS is low, the SN74AS298AN routes inputs A1–D1 to QA–QD on the next CLK↓; when WS is high, it routes A2–D2 instead. WS is sampled asynchronously but affects only the next clocked transfer - enabling dynamic source switching without disrupting ongoing register contents until the next edge.
Can the SN74AS298AN be used as a shift register?
Yes - the SN74AS298AN can implement a 4-bit universal shift register. By cascading QA–QD outputs to A2–D2 inputs and controlling WS, it achieves 1-place shifts (WS = H) or 2-place shifts (WS toggled across cycles), as documented in TI's SDAS219B application figures for BCD and binary arithmetic.
What package type is used for the SN74AS298AN?
The SN74AS298AN uses a 16-pin plastic dual in-line package (PDIP), designated "N" by Texas Instruments, with 300-mil width and through-hole mounting. It is RoHS-compliant, rated for 0°C to 70°C operation, and marked "SN74AS298AN" on the top surface.
SN74AS298AN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AS
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- Multiplexer
- Circuit:
- 4 x 2:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- 2mA, 20mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
SN74AS298AN FAQ
1.How can I place an order for SN74AS298AN through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AS298AN 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 SN74AS298AN reliable?
The price and inventory of SN74AS298AN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AS298AN is usually 5 days.
3.What payment methods are accepted for SN74AS298AN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AS298AN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AS298AN?
SN74AS298AN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AS298AN 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 SN74AS298AN?
For technical support, including SN74AS298AN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AS298AN requirements.
6.How does Aetrix verify that SN74AS298AN is sourced from the original manufacturer or authorized distributors?
All SN74AS298AN 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 SN74AS298AN meets industry standards.
7.What is the process for return or replacement of SN74AS298AN?
All SN74AS298AN units undergo pre-shipment inspection (PSI). If there is an issue with SN74AS298AN, 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 SN74AS298AN part is unused and in its original packaging.
Return procedure for SN74AS298AN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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