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Texas Instruments SN74AS298ANSR
- Part No.:
- SN74AS298ANSR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74AS298ANSR.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,990
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Product details
Overview
SN74AS298ANSR from Texas Instruments is a quadruple 2-input multiplexer with synchronous storage, functioning as a dual 4-bit selectable register with negative-edge clocking. It supports two independent 4-bit data sources (A1–D1 and A2–D2), selects between them via WS input, and latches selected word on CLK↓. Key specs include 62 MHz max clock frequency, 0.35 V VOL at 20 mA, and operation across 0°C to 70°C - used in arithmetic processor operand routing and BCD shift registers.
For engineers reviewing the SN74AS298ANSR datasheet, SN74AS298ANSR pinout, SN74AS298ANSR application, or SN74AS298ANSR equivalent, this page delivers verified functional identity, confirmed timing behavior (tPLH ≤ 9 ns, tPHL ≤ 11 ns), storage capability per 4-bit word, WS-controlled source selection logic, and DIP-16 package mapping - all critical for legacy TTL system redesign and register-level control path validation.
Technical Context
The SN74AS298ANSR integrates multiplexing and edge-triggered storage in a single 16-pin device: two 4-bit words are presented at dedicated input groups (A1–D1 and A2–D2), with WS determining active source prior to CLK↓ sampling. Its internal structure combines four independent D-type flip-flops gated by a shared 2:1 selector, enabling atomic parallel load of either word without intermediate bus contention.
It operates strictly in positive-logic TTL-compatible voltage domains: VIH ≥ 2 V, VIL ≤ 0.8 V, VOH ≥ VCC−2 V, and VOL ≤ 0.5 V at IOL = 20 mA. Timing is defined exclusively on the negative-going edge of CLK, with setup/hold requirements of 4.5 ns (data) and 13 ns (WS), ensuring deterministic capture in synchronous arithmetic pipelines.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Quadruple 2-input multiplexer with synchronous storage - implements dual 4-bit register + selection in one IC |
| Max clock frequency | 62 MHz - enables high-speed operand switching in ALU data paths without pipeline stalls |
| Propagation delay (CLK→Q) | tPLH ≤ 9 ns, tPHL ≤ 11 ns - ensures tight timing closure in 4-bit parallel register chains |
| Output drive | IOL = 20 mA, IOH = −2 mA - directly interfaces with standard TTL loads without buffering |
| Supply range | VCC = 4.5 V to 5.5 V - compatible with legacy 5 V TTL power rails and noise margins |
| Operating temperature | 0°C to 70°C - qualified for commercial-grade embedded control and test equipment |
| Input thresholds | VIH ≥ 2 V, VIL ≤ 0.8 V - guarantees reliable recognition of TTL logic levels under worst-case fanout |
Pinout & Package
SN74AS298ANSR uses a 16-pin plastic dual in-line package (PDIP-N), 300-mil width, with through-hole mounting and industry-standard pin spacing. Pin 1 is top-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 output when WS = H |
| 2 | A2 | Bit-1 input of second 4-bit word - routed to QA output when WS = H |
| 3 | A1 | Bit-1 input of first 4-bit word - routed to QA output when WS = L |
| 4 | B1 | Bit-2 input of first 4-bit word - routed to QB output when WS = L |
| 5 | C2 | Bit-3 input of second 4-bit word - routed to QC output when WS = H |
| 6 | D2 | Bit-4 input of second 4-bit word - routed to QD output when WS = H |
| 7 | D1 | Bit-4 input of first 4-bit word - routed to QD output when WS = L |
| 8 | GND | Ground reference - return path for all inputs, outputs, and internal logic |
| 9 | VCC | Positive supply - powers internal TTL circuitry at 4.5–5.5 V |
| 10 | QA | Stored bit-1 output - reflects A1 or A2 based on WS state at last CLK↓ |
| 11 | QB | Stored bit-2 output - reflects B1 or B2 based on WS state at last CLK↓ |
| 12 | QC | Stored bit-3 output - reflects C1 or C2 based on WS state at last CLK↓ |
| 13 | QD | Stored bit-4 output - reflects D1 or D2 based on WS state at last CLK↓ |
| 14 | CLK | Clock input - negative-edge triggered; initiates synchronous latch of selected word |
| 15 | WS | Word-select control - L selects word 1 (A1–D1), H selects word 2 (A2–D2) |
| 16 | C1 | Bit-3 input of first 4-bit word - routed to QC output when WS = L |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous dual-word selection | Atomic switch between two full 4-bit operands on single CLK↓ - eliminates race conditions in ALU register file access |
| Negative-edge clocking | Guaranteed setup/hold timing referenced to CLK falling edge - simplifies synchronization with master system clocks |
| TTL-compatible I/O | Meets standard 74AS voltage thresholds and drive strength - interoperable with legacy 5 V logic families without level shifting |
| Parallel-load shift register mode | Configurable as 1-place or 2-place BCD/binary shifter using WS control - reduces gate count vs discrete register + mux solutions |
| Single-package integration | Replaces SN74AS157 (mux) + SN74AS175A (quad FF) - saves PCB area and interconnect complexity in space-constrained designs |
Applications
| Arithmetic Processor Operand Routing | BCD Digit Shift Register |
|---|---|
Use Scenario: Arithmetic logic unit requires rapid alternation between two operand sources - e.g., accumulator and immediate constant - during multi-cycle computation. IC Role / Device Role / Timing Role: SN74AS298ANSR acts as a synchronized operand selector and temporary hold register, presenting selected 4-bit data to ALU inputs on each CLK↓. Use Value: Enables register file release for new data acquisition while maintaining operand integrity - improves throughput in microcoded arithmetic engines. |
Use Scenario: Decimal digit manipulation in calculator or metering hardware where BCD digits must be shifted left/right within a multi-digit display buffer. IC Role / Device Role / Timing Role: SN74AS298ANSR functions as a universal 4-bit shift register, with WS controlling 1-place (WS=L) or 2-place (WS=H) shift per clock cycle. Use Value: Achieves full-digit BCD shift in one clock pulse - eliminates iterative single-bit shifts and reduces firmware overhead in digit-positioning routines. |
| ALU-Controlled Multiplier Support | Parallel-Load Register Bank |
Use Scenario: Hardware multiplier implementation requiring dynamic alignment of partial products before addition, with variable shift distances per cycle. IC Role / Device Role / Timing Role: SN74AS298ANSR serves as a programmable shift-stage register, accepting ALU output and applying configurable shift (1 or 2 bits) under WS control. Use Value: Reduces external logic count for shift control - allows multiplier datapath to scale with minimal added gates beyond core ALU. |
Use Scenario: Embedded controller needing fast context save/restore of 4-bit status flags or configuration bits across interrupt service routines. IC Role / Device Role / Timing Role: SN74AS298ANSR operates as a dual-port register bank: one port accepts new data (A1–D1/A2–D2), the other provides stable output (QA–QD) until next CLK↓. Use Value: Supports atomic parallel load of updated flag set while preserving previous state - prevents transient invalid states during context switches. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 4-bit synchronous multiplexer/register applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AS157N + SN74AS175N | Two separate ICs: quad 2-input mux + quad D-type flip-flop - requires additional board area and interconnect wiring | Same logical function but split across two packages - increases layout complexity and signal routing delays | Choose when existing design already uses these components or when separate control of mux and latch timing is required |
| SN74F298N | F-series TTL version: slower (max 35 MHz), higher VOL (0.5 V), lower drive (IOL = 12 mA) - not drop-in compatible due to timing and drive mismatch | Acceptable only in low-speed legacy systems where 62 MHz performance and 20 mA sink are not required | Choose only for cost-sensitive replacements in non-critical timing paths where SN74AS298ANSR's speed and drive are unnecessary |
Compared with SN74AS157N+SN74AS175N, SN74AS298ANSR consolidates functionality into one package with tighter timing and reduced interconnect skew; versus SN74F298N, it delivers 77% higher clock rate and 67% stronger output sink capability - critical for noise-immune, high-throughput arithmetic subsystems.
Availability
SN74AS298ANSR is available at Aetrix Electronics and suitable for arithmetic processor design, BCD-based instrumentation, legacy TTL system repair, and educational digital logic labs requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74AS298ANSR 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 technologies with broad industrial, automotive, and communications reach.
The SN74AS298ANSR belongs to TI's 74AS advanced Schottky TTL logic family - engineered for high-speed, low-power 5 V digital systems requiring precise timing, robust noise immunity, and direct compatibility with legacy TTL infrastructure.
FAQ
What is the primary function of the SN74AS298ANSR?
The SN74AS298ANSR is a quadruple 2-input multiplexer with integrated synchronous storage. It selects one of two 4-bit data words (A1–D1 or A2–D2) based on the WS input and latches the chosen word to outputs QA–QD on the negative edge of CLK. This enables atomic operand switching and register-like behavior in a single 16-pin PDIP package - ideal for arithmetic processor data routing and BCD shift register implementations.
Does SN74AS298ANSR support 3-state outputs?
No, the SN74AS298ANSR does not feature 3-state outputs. All outputs (QA–QD) are push-pull totem-pole drivers with fixed active-high logic levels. Its electrical characteristics specify IOH = −2 mA and IOL = 20 mA under standard conditions - confirming standard TTL-compatible output structure without enable/disable control. For bus-sharing applications, external tri-state buffers or alternative devices like SN74AS299 would be required.
What is the maximum operating clock frequency for SN74AS298ANSR?
The SN74AS298ANSR is characterized for a maximum clock frequency of 62 MHz over the full 0°C to 70°C operating range. This value is specified in the "Timing Requirements" section of the datasheet and validated under recommended conditions (VCC = 4.5 V to 5.5 V, CL = 50 pF). Operation above this frequency risks setup/hold violations, particularly for WS (tsu = 13 ns) and data inputs (tsu = 4.5 ns), and is not guaranteed by Texas Instruments.
Can SN74AS298ANSR be used as a shift register?
Yes, the SN74AS298ANSR can be configured as a 4-bit shift register. By cascading multiple units and controlling WS, it implements 1-place or 2-place shifts per clock cycle - as demonstrated in TI's Application Information (Figures 1 and 2). When WS = L, it shifts one position; when WS = H, it shifts two positions. This capability is intrinsic to its architecture and requires no external logic beyond inter-stage connections - making SN74AS298ANSR a compact solution for BCD or binary digit alignment tasks.
Is SN74AS298ANSR RoHS compliant?
Yes, SN74AS298ANSR is RoHS compliant. According to TI's Packaging Information Addendum, the SN74AS298AN and SN74AS298AN.A variants carry "Yes" for RoHS compliance, with NIPDAU lead finish and no exemption applied. The ".A" suffix denotes tape-and-reel packaging, while the base SN74AS298ANSR (where "SR" indicates tube packaging per TI's ordering nomenclature) shares identical material composition and compliance status - confirmed via TI's official product change notices and packaging data sheets.
SN74AS298ANSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AS
- Package/Case:
- 16-SOIC (0.209", 5.30mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- 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:
- Surface Mount
- Supplier Device Package:
- 16-SO
SN74AS298ANSR FAQ
1.How can I place an order for SN74AS298ANSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AS298ANSR 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 SN74AS298ANSR reliable?
The price and inventory of SN74AS298ANSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AS298ANSR is usually 5 days.
3.What payment methods are accepted for SN74AS298ANSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AS298ANSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AS298ANSR?
SN74AS298ANSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AS298ANSR 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 SN74AS298ANSR?
For technical support, including SN74AS298ANSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AS298ANSR requirements.
6.How does Aetrix verify that SN74AS298ANSR is sourced from the original manufacturer or authorized distributors?
All SN74AS298ANSR 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 SN74AS298ANSR meets industry standards.
7.What is the process for return or replacement of SN74AS298ANSR?
All SN74AS298ANSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AS298ANSR, 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 SN74AS298ANSR part is unused and in its original packaging.
Return procedure for SN74AS298ANSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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