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Texas Instruments SN74ALS74AD
- Part No.:
- SN74ALS74AD
- Manufacturer:
- Texas Instruments
- Category:
- Flip Flops
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74ALS74AD.pdf
- Description:
- IC FF D-TYPE DUAL 1BIT 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:155
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Product details
Overview
SN74ALS74AD from Texas Instruments is a dual positive-edge-triggered D-type flip-flop IC in SOIC-14 package, operating from 0°C to 70°C with 5 V supply, 34 MHz max clock frequency (CL = 50 pF), 6 mW typical power per flip-flop, and TTL-compatible input thresholds. It serves as a synchronous storage element in digital control logic, bus interface timing, and state machine sequencing.
For engineers reviewing the SN74ALS74AD datasheet, SN74ALS74AD pinout, SN74ALS74AD application, or SN74ALS74AD equivalent, this page delivers verified electrical specs, functional behavior under PRE/CLR override, propagation delay values at 5 V/50 pF, and direct alternatives for legacy 74ALS logic upgrades.
Technical Context
The SN74ALS74AD implements two independent edge-triggered D flip-flops with asynchronous active-low preset (PRE) and clear (CLR) inputs that override clocked data transfer. Its TTL-compatible input structure accepts VIH ≥ 2 V and VIL ≤ 0.8 V, and outputs drive ±4 mA (IOL = 8 mA min) into 500 Ω loads with CL = 50 pF.
Timing is defined by setup time (tsu = 15 ns), hold time (th = 0 ns), and propagation delays tPLH/tPHL from CLK to Q (16 ns/18 ns max). Clock triggering occurs at a fixed voltage threshold-not dependent on edge slew rate-ensuring robust operation across varying signal rise times.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | 74ALS (Advanced Low-Power Schottky) - balances speed and power vs. standard TTL |
| Max Clock Frequency | 34 MHz at VCC = 5 V, CL = 50 pF - supports medium-speed synchronous logic up to ~29 ns period |
| Supply Voltage Range | 4.5 V to 5.5 V - requires stable 5 V rail; not 3.3 V compatible |
| Output Drive Capability | IOL = 8 mA min, IOH = −0.4 mA min - sufficient to drive one standard TTL input or multiple 74ALS inputs |
| Propagation Delay | tPLH/tPHL = 16/18 ns max (CLK→Q) - enables reliable timing in sub-30 ns critical paths |
| Operating Temperature | 0°C to 70°C - commercial-grade rating; not rated for extended industrial or automotive ranges |
| Power Dissipation | 6 mW typical per flip-flop at 5 V - total ~12 mW static + dynamic - suitable for low-power board-level logic |
Pinout & Package
SN74ALS74AD uses a 14-pin SOIC (D) package with 1.27 mm pitch, 8.75 mm × 3.91 mm body, and 1.75 mm max height. Pin numbering follows JEDEC MS-012AB standard with Pin 1 in top-left corner (quadrant Q1).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | 1CLR | Asynchronous active-low clear for first flip-flop; forces 1Q = L, 1Q̅ = H when asserted |
| 2 | 1D | Data input for first flip-flop; sampled on rising CLK edge if PRE/CLR inactive |
| 3 | 1CLK | Positive-edge-triggered clock for first flip-flop; voltage-threshold triggered, not edge-rate dependent |
| 4 | 1PRE | Asynchronous active-low preset for first flip-flop; forces 1Q = H, 1Q̅ = L when asserted |
| 5 | 1Q | True output of first flip-flop; reflects stored D value after CLK↑ (if PRE/CLR inactive) |
| 6 | 1Q̅ | Inverted output of first flip-flop; complementary to 1Q |
| 7 | GND | Ground reference for all internal circuitry and I/O |
| 8 | VCC | +5 V supply pin; must be decoupled locally with 0.1 µF ceramic capacitor |
| 9 | 2CLR | Asynchronous active-low clear for second flip-flop; independent of first section |
| 10 | 2D | Data input for second flip-flop; functionally identical to 1D |
| 11 | 2CLK | Positive-edge-triggered clock for second flip-flop; electrically isolated from 1CLK |
| 12 | 2PRE | Asynchronous active-low preset for second flip-flop; independent of first section |
| 13 | 2Q | True output of second flip-flop; fully independent timing path from first |
| 14 | 2Q̅ | Inverted output of second flip-flop; complements 2Q |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent D flip-flops | Enables compact implementation of two-bit registers or split control paths without inter-stage coupling |
| Asynchronous PRE/CLR | Allows immediate state initialization or reset without waiting for next clock edge - critical for power-up sequencing |
| TTL-compatible thresholds | VIH = 2 V min / VIL = 0.8 V max ensures interoperability with legacy 74LS/74S logic families |
| Low power consumption | 6 mW per flip-flop at 5 V reduces thermal load in dense logic arrays and extends battery life in portable systems |
| SOIC-14 surface-mount package | Enables automated assembly and higher board density vs. through-hole PDIP variants |
Applications
| Industrial Control Sequencing | Digital Bus Interface Logic |
|---|---|
Use Scenario: Synchronizing sensor sampling pulses and actuator enable signals in PLC I/O modules. IC Role / Device Role / Timing Role: Dual D flip-flop provides edge-aligned register staging between microcontroller GPIO and field-side isolation drivers. Use Value: Asynchronous CLR ensures deterministic startup state; 34 MHz clock support handles 20 µs cycle-time requirements. | Use Scenario: Latching address/data strobes in 8-bit parallel bus communication between MCU and peripheral ASIC. IC Role / Device Role / Timing Role: Stores bus state during handshake phases; PRE/CLR manages bus arbitration and error recovery. Use Value: 16 ns CLK→Q propagation enables tight timing margins in 50 ns bus cycles; SOIC-14 footprint fits constrained routing zones. |
| Legacy System Repair & Refurbishment | Education & Digital Logic Labs |
Use Scenario: Replacing obsolete 74LS74 in vintage test equipment where PCB layout cannot accommodate new footprints. IC Role / Device Role / Timing Role: Pin-compatible drop-in replacement preserving original timing behavior and drive strength. Use Value: Identical SOIC-14 pinout and 74ALS logic levels ensure no schematic or layout changes required; 6 mW dissipation matches thermal profile. | Use Scenario: Teaching sequential logic fundamentals including setup/hold timing, metastability, and asynchronous control in university labs. IC Role / Device Role / Timing Role: Demonstrates real-world DFF behavior with measurable propagation delays and PRE/CLR override effects. Use Value: Clear pin labeling and documented 15 ns setup time allow precise oscilloscope-based timing validation using standard function generators. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual D-type flip-flop applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS74AN | Same electrical specs and logic function; PDIP-14 through-hole package instead of SOIC-14 | Used where manual prototyping, socketing, or legacy through-hole assembly is required | Select SN74ALS74AN for breadboard evaluation or repair of older PCBs with DIP footprints |
| SN74AS74ADR | Higher speed (105 MHz max), higher power (16 mA ICC), AS family - not pin/function identical but same pinout | Suitable for performance-critical paths where 34 MHz is insufficient, but requires updated timing analysis | Choose SN74AS74ADR only when clock rates exceed 34 MHz and board-level power budget allows +10 mA additional supply current |
Compared with SN74ALS74AN, the SN74ALS74AD offers identical logic behavior in a surface-mount package for automated production; versus SN74AS74ADR, it trades speed for lower power and proven stability in established 74ALS designs.
Availability
SN74ALS74AD is available at Aetrix Electronics and suitable for industrial control sequencing, digital bus interface logic, and legacy system refurbishment requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS74AD 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 global semiconductor leader founded in 1930, specializing in analog, embedded processing, and logic solutions with deep heritage in TTL and advanced logic families.
The SN74ALS74AD belongs to TI's 74ALS logic series, designed specifically for cost-sensitive, medium-speed digital systems requiring better power-speed tradeoffs than standard 74LS while maintaining full TTL compatibility.
FAQ
Is SN74ALS74AD compatible with 3.3 V logic systems?
No, SN74ALS74AD is not 3.3 V compatible. Its absolute maximum supply voltage is 7 V, but recommended operation requires 4.5 V to 5.5 V. Input thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V) and output swing (VOH ≈ VCC−2 V) are specified for 5 V operation. Using SN74ALS74AD with 3.3 V supplies risks unreliable switching and violates recommended operating conditions.
What is the meaning of the "D" suffix in SN74ALS74AD?
The "D" suffix in SN74ALS74AD denotes the SOIC (Small Outline Integrated Circuit) package type - a 14-pin surface-mount package with 1.27 mm lead pitch and JEDEC MS-012AB outline. This distinguishes it from the "N" (PDIP) and "J" (CDIP) variants. The SN74ALS74AD is functionally identical to SN74ALS74AN but optimized for automated PCB assembly.
Does SN74ALS74AD support simultaneous preset and clear assertion?
No, asserting both PRE and CLR low simultaneously places SN74ALS74AD outputs in an undefined, nonstable state (per Function Table footnote †). The outputs do not meet VOH/VOL specifications and will not retain state when either input returns high. Design practice requires mutually exclusive activation of PRE and CLR, or use of external gating to prevent concurrent assertion.
Can SN74ALS74AD replace SN74LS74 in existing designs?
Yes, SN74ALS74AD is a direct functional and pinout replacement for SN74LS74 in SOIC-14 format. It offers improved speed (34 MHz vs. 25 MHz), lower power (6 mW vs. 10 mW per FF), and identical TTL-compatible thresholds. No schematic or layout changes are needed, though decoupling and thermal design should be re-verified due to different AC characteristics.
What is the minimum pulse width required for SN74ALS74AD clock input?
The minimum pulse width for SN74ALS74AD clock input is 14.5 ns for both high and low states (tw(CLK high) and tw(CLK low)), per Recommended Operating Conditions table. This ensures reliable edge detection given the voltage-threshold triggering mechanism. Pulses shorter than 14.5 ns may result in missed or metastable transitions - verify with oscilloscope measurement of actual CLK waveform at the SN74ALS74AD pin.
SN74ALS74AD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Function:
- Set(Preset) and Reset
- Type:
- D-Type
- Output Type:
- Complementary
- Number of Elements:
- 2
- Number of Bits per Element:
- 1
- Clock Frequency:
- 34 MHz
- Max Propagation Delay @ V, Max CL:
- 18ns @ 5V, 50pF
- Trigger Type:
- Positive Edge
- Current - Output High, Low:
- 400µA, 8mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Current - Quiescent (Iq):
- 4 mA
- Input Capacitance:
- -
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SOIC
SN74ALS74AD FAQ
1.How can I place an order for SN74ALS74AD through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS74AD 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 SN74ALS74AD reliable?
The price and inventory of SN74ALS74AD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS74AD is usually 5 days.
3.What payment methods are accepted for SN74ALS74AD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS74AD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS74AD?
SN74ALS74AD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS74AD 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 SN74ALS74AD?
For technical support, including SN74ALS74AD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS74AD requirements.
6.How does Aetrix verify that SN74ALS74AD is sourced from the original manufacturer or authorized distributors?
All SN74ALS74AD 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 SN74ALS74AD meets industry standards.
7.What is the process for return or replacement of SN74ALS74AD?
All SN74ALS74AD units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS74AD, 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 SN74ALS74AD part is unused and in its original packaging.
Return procedure for SN74ALS74AD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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