SN74ALS Advanced Low-Power Schottky TTL Variants
Texas Instruments SN74ALS devices are 5 V Advanced Low-Power Schottky TTL logic parts for legacy gates, buffers, drivers, registers, and bus-interface applications.
Advanced Schottky TTL logic for 5 V legacy systems
Compare SN74ALS functions by output type, fanout, package, timing, and TTL compatibility.
The SN74ALS family is Texas Instruments' Advanced Low-Power Schottky TTL logic line. It was developed to improve speed and power behavior compared with earlier TTL generations while retaining 5 V TTL input and output conventions. The family includes gates, inverters, open-collector devices, buffers, latches, registers, drivers, and bus transceivers used in legacy computing, industrial controls, communications boards, and test equipment.
ALS logic remains relevant when an existing product cannot be changed to CMOS without timing, loading, or threshold risk. Compared with LS, ALS devices may offer faster switching or different drive behavior depending on the function. Before replacing an ALS part, verify supply limits, input current, output sink/source requirements, propagation delay, output-enable timing, open-collector behavior, package, and operating temperature.
Key Features
- Advanced TTL family for 5 V legacy digital systems
- Covers standard gates, bus drivers, registers, and interface logic
- Useful where TTL loading and timing must be preserved
- Often compared against LS, AS, HCT, and AHCT replacements
- Requires exact output topology and fanout verification
Target Applications
- Legacy computing and control boards
- Industrial automation service parts
- 5 V bus drivers and receivers
- Test equipment maintenance
- Timing-sensitive TTL logic paths
Ordering Variants
Compare 221 SN74ALS part numbers by package, electrical parameters, lifecycle, and availability. Use RFQ for stock and lead-time confirmation.
| Part Number | Description | Package Type | Manufacturer | Lifecycle | RoHS | Availability | Action |
|---|---|---|---|---|---|---|---|
| SN74ALS646-1NT | Package: PDIP | Mounting Type: Through Hole | Logic Function: Bus Transceiver/Register | Max Operating Temp: 70°C | Min Operating Temp: 0°C | PDIP | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS646NT | Package: PDIP | Mounting Type: Through Hole | Logic Function: Bus Transceiver/Register | Max Operating Temp: 70°C | Min Operating Temp: 0°C | PDIP | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS540N | Package: PDIP | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Number of Channels: 8 | Number of Outputs: 8 | Number of Bits: 8 | Logic Function: Buffer, Inverter | PDIP | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS641A-1N | Package: PDIP | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Number of Channels: 8 | Number of Outputs: 8 | Number of Bits: 8 | Logic Function: Transceiver, Inverting | PDIP | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS666DW | Package: SOIC | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Output Current: 24mA | Number of Bits: 8 | Logic Function: D-Type, Latch | Max Operating Temp: 70°C | SOIC | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS163BN | Package: PDIP | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Number of Bits: 4 | Frequency: 40MHz | Logic Function: Counter | Max Operating Temp: 70°C | PDIP | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS191AD | Package: SOIC | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Number of Bits: 4 | Frequency: 30MHz | Logic Function: Counter | Max Operating Temp: 70°C | SOIC | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS561ADW | Package: SOIC | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Number of Bits: 4 | Frequency: 30MHz | Logic Function: Counter | Max Operating Temp: 70°C | Min Operating Temp: 0°C | SOIC | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS569ADW | Package: SOIC | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Number of Bits: 4 | Frequency: 30MHz | Logic Function: Counter | Max Operating Temp: 70°C | Min Operating Temp: 0°C | SOIC | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS112AD | Package: SOIC | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Output Current: 8mA | Number of Bits: 2 | Frequency: 30MHz | Max Frequency: 30MHz | SOIC | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS175DRG4 | Package: SOIC | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Output Current: 8mA | Number of Bits: 4 | Frequency: 50MHz | Logic Function: D-Type, Flip-Flop | SOIC | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS175NSRE4 | Package: SOP | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Output Current: 8mA | Number of Bits: 4 | Frequency: 50MHz | Logic Function: D-Type, Flip-Flop | SOP | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS175NSRG4 | Package: SOP | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Output Current: 8mA | Number of Bits: 4 | Frequency: 50MHz | Logic Function: D-Type, Flip-Flop | SOP | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS574BN | Package: DIP | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Output Current: 24mA | Number of Channels: 8 | Number of Outputs: 8 | Number of Bits: 8 | DIP | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS74AD | Package: SOIC | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Output Current: 8mA | Number of Bits: 2 | Frequency: 34MHz | Max Frequency: 34MHz | SOIC | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS74ADR | Package: SOIC | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Output Current: 8mA | Number of Bits: 2 | Frequency: 34MHz | Logic Function: D-Type, Flip-Flop | SOIC | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS990N | Package: PDIP | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Output Current: 24mA | Number of Bits: 8 | Logic Function: D-Type, Latch | Max Operating Temp: 70°C | PDIP | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS05ADR | Package: SOIC | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Output Current: 8mA | Number of Channels: 6 | Number of Outputs: 6 | Number of Bits: 8 | SOIC | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS09D | Package: SOIC | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Output Current: 8mA | Max Output Current: 8mA | Number of Outputs: 1 | Number of Bits: 4 | SOIC | Texas Instruments | Active | Compliant | In Stock | |
| SN74ALS09N | Package: PDIP | Operating Supply Voltage: 5V | Max Supply Voltage: 5.5V | Min Supply Voltage: 4.5V | Output Current: 8mA | Max Output Current: 8mA | Number of Outputs: 1 | Number of Bits: 4 | PDIP | Texas Instruments | Active | Compliant | In Stock |
Ordering Code Differences
How suffixes on SN74ALS map to package, grade, and reel options.
[{"code":"SN74ALS00 / 02 / 04 / 08","meaning":"Common gate and inverter functions."},{"code":"SN74ALS244 / 245 / 541","meaning":"Bus buffer and transceiver functions with 3-state outputs."},{"code":"ALS vs LS","meaning":"Both are TTL families, but speed, power, and drive behavior differ by function."},{"code":"D, N, DW, DB suffixes","meaning":"Package and packing options such as SOIC, PDIP, wide SOIC, or SSOP."}]
How to Choose the Right SN74ALS Drivers, Receivers and Transceivers
Stay within TTL assumptions
Input current, fanout, and output current are part of the circuit behavior in ALS designs.
Check bus timing
3-state enable and disable timing matters on shared data buses.
Review CMOS replacements carefully
HCT or AHCT may be viable, but load, delay, and edge-rate effects must be reviewed.
Technical Specifications
Core parameters for SN74ALS product family
Source SN74ALS with Octatronics
Request stock confirmation, lead time, date code, and pricing for all 221 ordering variants from Texas Instruments. Our team supports active, EOL, and hard-to-find component sourcing.
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Frequently Asked Questions
Common technical questions about the SN74ALS product family.