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Texas Instruments SN74ALS174D
- Part No.:
- SN74ALS174D
- Manufacturer:
- Texas Instruments
- Category:
- Flip Flops
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74ALS174D.pdf
- Description:
- IC FF D-TYPE SNGL 6BIT 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,361
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Product details
Overview
SN74ALS174D from Texas Instruments is a hex D-type positive-edge-triggered flip-flop with asynchronous clear, implemented in advanced low-power Schottky (ALS) TTL logic. It features six independent D-flip-flops, single-rail outputs, buffered clock and clear inputs, 5 V nominal supply operation, 40 MHz maximum clock frequency, and 0°C to 70°C industrial temperature range - used in synchronous data latching and register storage within digital control systems.
For engineers reviewing the SN74ALS174D datasheet, SN74ALS174D pinout, SN74ALS174D application, or SN74ALS174D equivalent, this device is selected for reliable edge-triggered state capture in legacy TTL-compatible designs requiring deterministic setup/hold timing, noise-immune buffered inputs, and stable 16-pin SOIC packaging with industry-standard pin mapping.
Technical Context
The SN74ALS174D implements six identical D-type flip-flops sharing a common buffered clock (CLK) and direct-clear (CLR) input. Each flip-flop transfers the D-input value to its Q-output on the positive-going edge of CLK, provided setup time (15 ns) and hold time (0 ns) are met. CLR operates asynchronously, forcing all Q-outputs low regardless of CLK state.
All inputs and outputs conform to standard TTL voltage thresholds: VIH = 2 V min, VIL = 0.8 V max, VOH = VCC–2 V at –0.4 mA, VOL = 0.25 V max at 4 mA. The device exhibits fully buffered inputs for high noise immunity and is compatible with standard 74LS/74S logic families without level-shifting.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | Advanced Low-Power Schottky (ALS) TTL - ensures lower power than standard TTL while maintaining full 74LS compatibility and speed. |
| Flip-Flop Count | 6 independent D-type flip-flops - enables compact implementation of 6-bit registers or parallel load buffers in minimal board space. |
| Max Clock Frequency | 40 MHz - supports high-speed synchronous data capture in industrial controllers and test equipment. |
| Supply Voltage Range | 4.5 V to 5.5 V - tolerates typical 5 V rail variation without functional degradation or output instability. |
| Propagation Delay (tPLH/tPHL) | 3–20 ns (CLK→Q), 3–18 ns (CLR→Q) - guarantees predictable timing margins in critical control paths. |
| Output Drive Capability | IOL = 4 mA / IOH = –0.4 mA - sufficient to drive multiple TTL inputs or small capacitive loads directly. |
| Operating Temperature | 0°C to 70°C - qualified for commercial and industrial embedded applications with ambient thermal constraints. |
Pinout & Package
SN74ALS174D is housed in a 16-pin SOIC (Small Outline Integrated Circuit) package, 3.9 mm body width, 1.27 mm pitch, RoHS-compliant NiPdAu lead finish, MSL Level-1 rating. Pin 1 is located at the top-left corner with notch or dot marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | CLK | Buffered clock input - positive-edge sensitive; must meet 12.5 ns minimum pulse width high/low for reliable triggering. |
| 2 | 1D | Data input for Flip-Flop 1 - sampled on CLK↑ if setup/hold timing is satisfied. |
| 3 | 1Q | True output of Flip-Flop 1 - active-high, non-inverted latch state. |
| 4 | 2D | Data input for Flip-Flop 2 - electrically isolated from other D inputs; no internal coupling. |
| 5 | 2Q | True output of Flip-Flop 2 - matches timing characteristics of 1Q across temperature and voltage. |
| 6 | 3D | Data input for Flip-Flop 3 - shares same electrical specs as 1D/2D but physically separate terminal. |
| 7 | 3Q | True output of Flip-Flop 3 - provides deterministic propagation delay relative to CLK and 3D. |
| 8 | GND | Ground reference - all internal logic and I/O referenced to this node; requires low-impedance PCB connection. |
| 9 | 4D | Data input for Flip-Flop 4 - supports independent data loading per channel without gating logic. |
| 10 | 4Q | True output of Flip-Flop 4 - maintains consistent DC and AC output behavior with other Q pins. |
| 11 | 5D | Data input for Flip-Flop 5 - enables full 6-bit parallel data path when used with pins 12–16. |
| 12 | 5Q | True output of Flip-Flop 5 - synchronized to same CLK edge as all other Q outputs. |
| 13 | 6D | Data input for Flip-Flop 6 - completes the hex configuration; no NC or unused D terminals. |
| 14 | 6Q | True output of Flip-Flop 6 - final output in sequence; matches timing and drive strength of 1Q–5Q. |
| 15 | CLR | Asynchronous clear - active-low; forces all six Q outputs low immediately, overriding CLK and D states. |
| 16 | VCC | Positive supply - must be decoupled locally (e.g., 0.1 µF ceramic) to suppress switching noise on shared rail. |
Key Features
| Feature | Design Value |
|---|---|
| Positive-edge-triggered D flip-flops | Six independent channels synchronized to rising CLK edge - eliminates metastability risk in properly timed systems. |
| Asynchronous active-low clear | Immediate reset of all Q outputs regardless of clock phase - essential for system initialization and fault recovery. |
| Buffered clock and clear inputs | High noise immunity and fan-out capability - reduces sensitivity to signal integrity issues on control lines. |
| Single-rail Q outputs only | No complementary (Q̅) outputs - simplifies PCB routing and reduces pin count vs. dual-rail variants like 'ALS175. |
| TTL-compatible voltage thresholds | Direct interface with 74LS, 74S, and microcontroller GPIOs without level translation - lowers BOM cost. |
Applications
| Industrial PLC Input Register | Digital Test Equipment Data Capture |
|---|---|
|
Use Scenario: Capturing parallel sensor status bits (e.g., limit switches, encoder states) into a programmable logic controller's input image. IC Role / Device Role / Timing Role: SN74ALS174D acts as a synchronized input latch, sampling 6-bit status on a system clock edge to prevent race conditions during scan cycle updates. Use Value: Ensures deterministic, glitch-free registration of real-time I/O states with 15 ns setup margin - critical for safety-critical motion control sequencing. |
Use Scenario: Capturing stimulus-response data from DUT (device under test) during automated boundary-scan or functional testing. IC Role / Device Role / Timing Role: SN74ALS174D serves as a high-fidelity parallel data sampler, aligning captured signals to a precision test clock for timing analysis. Use Value: Delivers sub-20 ns propagation consistency across all six channels - enabling accurate timestamp correlation of multi-signal events. |
| Legacy Computer Bus Interface | Motor Control State Buffer |
|
Use Scenario: Interfacing 6-bit address/data bus segments between vintage microprocessors (e.g., Z80, 6502) and peripheral ICs. IC Role / Device Role / Timing Role: SN74ALS174D functions as a bus register, holding address latches or I/O port data during memory-mapped transactions. Use Value: Maintains full 74LS timing compatibility and drive strength - ensuring seamless integration into retrocomputing hardware without redesign. |
Use Scenario: Storing commutation sequence states for 3-phase brushless DC motor drivers using discrete gate drivers. IC Role / Device Role / Timing Role: SN74ALS174D holds the 6-bit PWM enable pattern for upper/lower FET pairs, updated synchronously with motor position feedback. Use Value: Provides robust, low-jitter state retention with asynchronous CLR for emergency stop - improving torque stability and EMI performance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar D-type flip-flop applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS174N | Same logic function and timing, but in 16-pin PDIP package - larger footprint, through-hole mounting, higher thermal resistance (67°C/W). | Preferred for prototyping, breadboarding, or legacy through-hole PCBs where SOIC reflow is unavailable. | Select SN74ALS174N when manual assembly, socketing, or thermal derating above 70°C is required. |
| SN74AS174D | Faster propagation (3.5–8 ns vs. 3–20 ns) and higher clock rate (100 MHz), but higher ICC (30–45 mA vs. 11–19 mA) and tighter layout requirements. | Better suited for high-speed test instrumentation or clock-domain bridging where ALS timing is marginal. | Choose SN74AS174D only when >40 MHz operation is mandatory and power/thermal budget allows. |
Compared with SN74ALS174N and SN74AS174D, the SN74ALS174D delivers optimal balance of speed, power efficiency, and SOIC manufacturability for industrial control and legacy digital systems - avoiding unnecessary complexity or cost overhead.
Availability
SN74ALS174D is available at Aetrix Electronics and suitable for industrial PLC input registers, digital test equipment data capture, legacy computer bus interfaces, and motor control state buffering requiring stable component supply across extended production lifecycles.
Supply support for SN74ALS174D 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 90 years of innovation in industrial, automotive, and communications markets.
The SN74ALS174D belongs to TI's legacy 74ALS logic family, designed specifically for high-reliability, medium-speed digital control applications where TTL compatibility, low power, and long-term supply stability are prioritized over cutting-edge speed.
FAQ
What is the maximum clock frequency supported by the SN74ALS174D?
The SN74ALS174D supports a maximum clock frequency of 40 MHz under recommended operating conditions (VCC = 4.5 V to 5.5 V, TA = 0°C to 70°C, CL = 50 pF). This is confirmed in the switching characteristics table of the SDAS207E datasheet, where fmax is specified as 40 MHz for SN74ALS174 devices. Exceeding this frequency risks setup/hold violations and metastability.
Does the SN74ALS174D provide complementary (Q̅) outputs?
No, the SN74ALS174D provides only true (Q) outputs for each of its six flip-flops. Complementary outputs are available only in the 'ALS175 and 'AS175B variants, which contain four flip-flops with dual-rail outputs. The SN74ALS174D pinout and logic diagram explicitly show single-rail Q terminals (pins 3, 5, 7, 10, 12, 14) and no Q̅ connections.
What is the purpose of the NC (no internal connection) pins on the SN74ALS174D?
The SN74ALS174D has no NC pins - all 16 pins are assigned functional roles (CLK, six D inputs, six Q outputs, CLR, VCC, GND). Earlier documentation referencing NC pins applies to FK-package LCCC variants (e.g., SNJ54ALS174FK), not the SOIC-packaged SN74ALS174D. The D-package pinout is fully utilized with zero NC terminals.
How does the SN74ALS174D handle unused inputs in a design?
All unused inputs on the SN74ALS174D - including unconnected D inputs and the CLR line if not actively used - must be tied to a valid logic level (VCC or GND) to prevent floating states that cause excessive current draw or erratic output behavior. TI's SCBA004 application report mandates this practice for proper ALS device operation and reliability.
Is the SN74ALS174D RoHS compliant and what is its moisture sensitivity level?
Yes, the SN74ALS174D is RoHS compliant with NiPdAu lead finish and carries an MSL Level-1 rating (unlimited floor life at ≤30°C/60% RH), per TI's package addendum. This means it can be stored indefinitely under standard conditions and requires no baking prior to reflow soldering - simplifying manufacturing for Aetrix Electronics' production partners.
SN74ALS174D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Function:
- Master Reset
- Type:
- D-Type
- Output Type:
- Non-Inverted
- Number of Elements:
- 1
- Number of Bits per Element:
- 6
- Clock Frequency:
- 50 MHz
- Max Propagation Delay @ V, Max CL:
- 17ns @ 5V, 50pF
- Trigger Type:
- Positive Edge
- Current - Output High, Low:
- 400µA, 8mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Current - Quiescent (Iq):
- 19 mA
- Input Capacitance:
- -
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
SN74ALS174D FAQ
1.How can I place an order for SN74ALS174D through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS174D 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 SN74ALS174D reliable?
The price and inventory of SN74ALS174D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS174D is usually 5 days.
3.What payment methods are accepted for SN74ALS174D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS174D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS174D?
SN74ALS174D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS174D 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 SN74ALS174D?
For technical support, including SN74ALS174D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS174D requirements.
6.How does Aetrix verify that SN74ALS174D is sourced from the original manufacturer or authorized distributors?
All SN74ALS174D 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 SN74ALS174D meets industry standards.
7.What is the process for return or replacement of SN74ALS174D?
All SN74ALS174D units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS174D, 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 SN74ALS174D part is unused and in its original packaging.
Return procedure for SN74ALS174D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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