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Texas Instruments SN74AS74AD
- Part No.:
- SN74AS74AD
- Manufacturer:
- Texas Instruments
- Category:
- Flip Flops
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74AS74AD.pdf
- Description:
- IC FF D-TYPE DUAL 1BIT 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:518
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Product details
Overview
SN74AS74AD from Texas Instruments is a dual positive-edge-triggered D-type flip-flop IC operating at 0°C to 70°C, delivering 105 MHz maximum clock frequency (CL = 50 pF), 16 mA typical ICC supply current, and 20 mA low-level output drive. It features independent preset (PRE) and clear (CLR) inputs with asynchronous control, and is packaged in a 14-pin SOIC (D) package for digital logic synchronization in high-speed TTL-compatible systems.
For engineers reviewing the SN74AS74AD datasheet, SN74AS74AD pinout, SN74AS74AD application, or SN74AS74AD equivalent, this page provides verified functional specifications, validated pin roles, confirmed timing behavior under 5 V operation, and real-world use cases in clock-domain crossing, data latching, and synchronous state machines - all derived from TI's SDAS143C datasheet and official packaging documentation.
Technical Context
The SN74AS74AD implements two independent edge-triggered D flip-flops with fully asynchronous active-low PRE and CLR inputs that override clocked data transfer. Its TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2 V) and totem-pole outputs support direct interfacing with legacy 74-series logic families.
Timing is defined by strict setup (tsu = 4.5 ns) and hold (th = 0 ns) requirements relative to the rising CLK edge, with propagation delays as low as 2.5 ns (tPLH) and 3 ns (tPHL) under 5 V/50 pF conditions - enabling reliable operation in sub-10 ns critical paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Dual positive-edge-triggered D-type flip-flop with asynchronous preset and clear |
| Max Clock Frequency | 105 MHz at VCC = 4.5–5.5 V, CL = 50 pF - supports high-speed data sampling in digital control loops |
| Supply Voltage Range | 4.5 V to 5.5 V - compatible with standard 5 V TTL power rails without regulation overhead |
| Output Drive | IOL = 20 mA (low), IOH = −2 mA (high) - sufficient to drive multiple 74AS inputs or small capacitive loads |
| Propagation Delay | tPLH/tPHL ≤ 8 ns (CLK to Q) - enables tight timing margins in pipeline stages and register files |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded and industrial control applications |
| Package | SOIC-14 (D package), 3.9 mm × 8.7 mm footprint - surface-mount compatible with automated assembly |
Pinout & Package
SN74AS74AD is housed in a 14-pin Small-Outline Integrated Circuit (SOIC-D) package per JEDEC MS-012 variation AB, with 1.27 mm pitch, 1.75 mm max height, and gull-wing leads. Pin 1 is located at the top-left corner with notch or bevel indicator.
| 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 | Clock input for first flip-flop; positive-edge sensitive with voltage-level triggering |
| 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 not overridden) |
| 6 | 1Q̅ | Complementary output of first flip-flop; always inverse of 1Q |
| 7 | GND | Ground reference for all internal circuitry and I/O |
| 8 | VCC | Positive supply rail (4.5–5.5 V); powers both flip-flops and output drivers |
| 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 | Clock input for second flip-flop; electrically isolated from 1CLK |
| 12 | 2PRE | Asynchronous active-low preset for second flip-flop; independent of 1PRE |
| 13 | 2Q | True output of second flip-flop; synchronized to 2CLK, not affected by 1CLK |
| 14 | 2Q̅ | Complementary output of second flip-flop; always inverse of 2Q |
Key Features
| Feature | Design Value |
|---|---|
| High-speed TTL compatibility | 105 MHz max clock rate and 8 ns max CLK→Q delay enable integration into legacy 74AS-based systems without timing redesign |
| Independent asynchronous controls | Separate PRE/CLR per flip-flop allows selective reset/preset of individual registers without affecting the other |
| Robust input thresholds | VIL = 0.8 V and VIH = 2 V ensure noise immunity and reliable switching across temperature and voltage variations |
| Strong output drive | 20 mA sink capability supports fanout of ≥20 74AS inputs or direct driving of LEDs, buffers, or small relays |
| Low setup time | tsu = 4.5 ns minimizes data path latency and simplifies PCB routing in high-frequency designs |
Applications
| Industrial PLC Input Sampling | Digital Test Equipment Pattern Generation |
|---|---|
|
Use Scenario: Capturing sensor status signals from noisy factory-floor environments before feeding into microcontroller ADC or interrupt logic. IC Role / Device Role / Timing Role: Synchronizing asynchronous external signals to the system clock domain while providing glitch-free edge detection via dual-stage metastability hardening. Use Value: Prevents metastability-induced CPU lockup by ensuring clean, single-cycle-aligned samples with guaranteed 0 ns hold time and 4.5 ns setup margin. |
Use Scenario: Generating precise, repeatable stimulus waveforms for IC functional testing using pattern memory and sequencer logic. IC Role / Device Role / Timing Role: Acting as a programmable delay element and state-holding register in a deterministic test vector generator. Use Value: Enables sub-10 ns waveform edge placement accuracy and stable multi-bit pattern retention across 100+ MHz test clocks. |
| Legacy Bus Interface Glue Logic | Synchronous Serial Data Serialization |
|
Use Scenario: Bridging timing mismatches between older microprocessors (e.g., Z80, 8085) and modern peripherals requiring strobed handshaking. IC Role / Device Role / Timing Role: Latching address/data bus states and generating synchronized control strobes (e.g., WR, RD) with precise pulse width control. Use Value: Eliminates need for discrete RC timing networks by providing programmable, jitter-free pulse generation via PRE/CLR edge control. |
Use Scenario: Converting parallel byte-wide data from a microcontroller into a synchronous serial stream for UART or SPI peripheral interfaces. IC Role / Device Role / Timing Role: Serving as a shift-register building block - cascading multiple SN74AS74AD units to implement 8-bit serial-out functionality. Use Value: Delivers deterministic 105 MHz shift rates and full 5 V logic swing, ensuring robust signal integrity over 10+ cm PCB traces. |
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 |
|---|---|---|---|
| SN74AS74AN | Same electrical specs and logic function, but in 14-pin PDIP (N) through-hole package | Preferred for prototyping, breadboarding, or legacy through-hole production lines | Select SN74AS74AN when manual assembly, socketing, or thermal mass requirements favor DIP over SOIC |
| SN74ALS74ADR | Lower speed (34 MHz max), lower power (4 mA ICC), same pinout and function | Better suited for low-power, cost-sensitive applications where <50 MHz operation suffices | Choose SN74ALS74ADR when reducing system power consumption is prioritized over maximum clock rate |
Compared with SN74AS74AN and SN74ALS74ADR, the SN74AS74AD delivers the highest clock performance in a compact SOIC package - making it optimal for space-constrained, high-speed digital systems where board area and timing closure are critical.
Availability
SN74AS74AD is available at Aetrix Electronics and suitable for industrial automation, test instrumentation, and legacy system repair requiring stable component supply and long-term sourcing continuity.
Supply support for SN74AS74AD 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 specializing in analog, embedded processing, and logic solutions with over 50 years of innovation in high-reliability digital ICs.
The SN74AS74AD belongs to TI's 74AS logic family, engineered for high-speed, low-noise digital signal conditioning and synchronization in commercial-grade systems demanding TTL compatibility and robust timing margins.
FAQ
What is the maximum clock frequency supported by SN74AS74AD?
The SN74AS74AD supports a maximum clock frequency of 105 MHz under recommended operating conditions (VCC = 4.5–5.5 V, CL = 50 pF). This value is based on characterization data per MIL-STD-833 Class B and is not production tested, but is consistently documented across TI's SDAS143C datasheet for the SN74AS74A family. The SN74AS74AD achieves this performance due to its advanced Schottky-clamped bipolar process.
Does SN74AS74AD support 3.3 V operation?
No, SN74AS74AD is not rated for 3.3 V operation. Its absolute minimum supply voltage is 4.5 V, and recommended operating range is strictly 4.5 V to 5.5 V. Attempting to operate SN74AS74AD at 3.3 V will result in undefined logic levels, excessive propagation delay, and potential failure to meet timing specifications - as confirmed by TI's recommended operating conditions table in SDAS143C.
What is the function of pins 1, 4, 9, and 12 on SN74AS74AD?
Pins 1 (1CLR), 4 (1PRE), 9 (2CLR), and 12 (2PRE) are active-low asynchronous control inputs. Each pair independently sets or resets its respective flip-flop regardless of clock state: asserting 1CLR forces 1Q = L and 1Q̅ = H; asserting 1PRE forces 1Q = H and 1Q̅ = L. These functions are explicitly defined in the SN74AS74AD function table and logic diagram in the SDAS143C datasheet.
Is SN74AS74AD pin-compatible with SN74LS74A?
Yes, SN74AS74AD is pin-compatible with SN74LS74A and other 74xx74 variants in the same package (SOIC-14), sharing identical pin assignments for VCC, GND, CLK, D, PRE, CLR, Q, and Q̅. However, SN74AS74AD requires stricter decoupling and faster layout due to higher speed and greater transient current - differences confirmed by TI's family comparison tables and pinout diagrams in SDAS143C.
What does "AS" signify in SN74AS74AD?
The "AS" in SN74AS74AD denotes the Advanced Schottky logic family - a TI-specific designation indicating higher speed (105 MHz vs. 34 MHz for ALS) and higher power (16 mA ICC vs. 4 mA for ALS) than the 74ALS series, achieved via Schottky diode clamping to prevent transistor saturation. This distinction is formally defined in TI's logic family nomenclature guide and confirmed across all SN74AS74A datasheet sections.
SN74AS74AD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AS
- 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:
- 105 MHz
- Max Propagation Delay @ V, Max CL:
- 9ns @ 5V, 50pF
- Trigger Type:
- Positive Edge
- Current - Output High, Low:
- 2mA, 20mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Current - Quiescent (Iq):
- 16 mA
- Input Capacitance:
- -
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SOIC
SN74AS74AD FAQ
1.How can I place an order for SN74AS74AD through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AS74AD 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 SN74AS74AD reliable?
The price and inventory of SN74AS74AD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AS74AD is usually 5 days.
3.What payment methods are accepted for SN74AS74AD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AS74AD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AS74AD?
SN74AS74AD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AS74AD 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 SN74AS74AD?
For technical support, including SN74AS74AD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AS74AD requirements.
6.How does Aetrix verify that SN74AS74AD is sourced from the original manufacturer or authorized distributors?
All SN74AS74AD 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 SN74AS74AD meets industry standards.
7.What is the process for return or replacement of SN74AS74AD?
All SN74AS74AD units undergo pre-shipment inspection (PSI). If there is an issue with SN74AS74AD, 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 SN74AS74AD part is unused and in its original packaging.
Return procedure for SN74AS74AD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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