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Texas Instruments SN74HCT74PW
- Part No.:
- SN74HCT74PW
- Manufacturer:
- Texas Instruments
- Category:
- Flip Flops
- Package:
- 14-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74HCT74PW.pdf
- Description:
- IC FF D-TYPE DUAL 1BIT 14TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,116
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Product details
Overview
SN74HCT74PW from Texas Instruments is a dual D-type positive-edge-triggered flip-flop with independent preset (PRE) and clear (CLR) inputs, operating at 4.5–5.5 V supply, delivering 17 ns typical propagation delay (tpd), ±4-mA output drive at 5 V, and TTL-compatible input thresholds. It serves as a synchronous storage element in digital control logic, clock-domain synchronization, and state-machine sequencing.
For engineers reviewing the SN74HCT74PW datasheet, SN74HCT74PW pinout, SN74HCT74PW application, or SN74HCT74PW equivalent, this page provides verified functional identity, TSSOP-14 package mapping, timing and DC electrical specifications, real-world use scenarios, and two validated alternative parts for design continuity.
Technical Context
The SN74HCT74PW implements two identical, electrically isolated D-type flip-flops sharing no internal signal paths. Each flip-flop responds to the rising edge of CLK only when both PRE and CLR are high; asynchronous assertion of PRE (low) forces Q = HIGH, while CLR (low) forces Q = LOW - overriding clock and data.
Its HCT logic family ensures TTL-voltage compatibility (VIH = 2 V, VIL = 0.8 V) with CMOS power efficiency (ICC ≤ 40 μA max), enabling direct interfacing with legacy TTL systems without level shifters while maintaining low static power in battery-sensitive or thermally constrained designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard 5-V logic rails and tolerant of ±5% regulation variation. |
| Propagation Delay (tpd) | 17 ns typical at 5.5 V - enables reliable operation up to 24 MHz clock frequency in synchronous logic chains. |
| Output Drive | ±4 mA at 5 V - sufficient to directly drive 10 LSTTL loads without buffering in mixed-logic systems. |
| Input Current | ≤ 1 μA max - eliminates need for pull-up/down resistors on unused inputs in low-power standby modes. |
| Setup Time (tsu) | 14 ns max at 5.5 V - defines minimum data stability window before CLK rising edge for deterministic sampling. |
| Power Dissipation Cap. | 35 pF per flip-flop - used to calculate dynamic power (P = Cpd × V² × f) for thermal budgeting. |
Pinout & Package
TSSOP-14 package (5.00 mm × 4.40 mm body, 0.65 mm pitch), 1.2 mm max height, RoHS-compliant, moisture sensitivity level 1 (260°C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | 1CLR | Asynchronous active-low clear for Flip-Flop 1 - forces Q1 = LOW regardless of CLK or D1 state. |
| 2 | 1D | Data input for Flip-Flop 1 - sampled on rising CLK edge when 1CLR and 1PRE are high. |
| 3 | 1CLK | Clock input for Flip-Flop 1 - positive-edge-triggered; voltage-level sensitive, not slew-rate dependent. |
| 4 | 1PRE | Asynchronous active-low preset for Flip-Flop 1 - forces Q1 = HIGH regardless of CLK or D1 state. |
| 5 | 1Q | True output of Flip-Flop 1 - reflects stored D1 value after valid CLK edge and setup/hold compliance. |
| 6 | 1Q̅ | Complementary output of Flip-Flop 1 - always inverse of 1Q; usable as feedback or enable signal. |
| 7 | GND | Ground reference for all internal circuitry and I/O - must be low-impedance connection to minimize noise coupling. |
| 8 | 2Q̅ | Complementary output of Flip-Flop 2 - electrically isolated from Flip-Flop 1; shares no internal nodes. |
| 9 | 2Q | True output of Flip-Flop 2 - independent timing behavior; same electrical specs as 1Q. |
| 10 | 2PRE | Asynchronous active-low preset for Flip-Flop 2 - no interaction with Flip-Flop 1 control signals. |
| 11 | 2CLK | Clock input for Flip-Flop 2 - fully independent; may be driven by separate clock domain or same source. |
| 12 | 2D | Data input for Flip-Flop 2 - no crosstalk or timing dependency on 1D or 1CLK. |
| 13 | 2CLR | Asynchronous active-low clear for Flip-Flop 2 - operates identically to 1CLR but on second flip-flop. |
| 14 | VCC | Positive supply rail - requires local 0.1-μF ceramic bypass capacitor placed within 3 mm of pin per TI layout guidance. |
Key Features
| Feature | Design Value |
|---|---|
| TTL-compatible inputs | VIH = 2 V, VIL = 0.8 V - allows direct connection to 74LS, 74F, and other TTL families without interface logic. |
| Asynchronous preset/clear | Dual independent PRE/CLR per flip-flop - enables hardware reset/set of state registers without clock dependency. |
| Low ICC | ≤ 40 μA max at 5.5 V - supports ultra-low-quiescent-current applications such as sleep-mode sequencers. |
| High noise immunity | Input hysteresis not specified, but guaranteed VIH/VIL margins provide ≥0.4 V noise margin at 5 V supply. |
| Robust ESD protection | Rated per JEDEC JS-001 Class 2 (≥2 kV HBM) - reduces risk of handling damage during PCB assembly. |
Applications
| Industrial PLC Input Latching | Microcontroller GPIO Expansion |
|---|---|
Use Scenario: Capturing momentary push-button or sensor signals in noisy factory environments where contact bounce or EMI could cause spurious edges. IC Role / Device Role / Timing Role: SN74HCT74PW acts as a synchronized debouncer - PRE/CLR initialize known state; CLK edge samples conditioned input via external RC filter. Use Value: Eliminates software polling or timer-based debounce, reducing MCU firmware complexity and ensuring deterministic 1-shot capture at system clock rate. |
Use Scenario: Extending limited GPIO count on an MCU to drive multiple LEDs, relays, or status indicators requiring independent on/off control. IC Role / Device Role / Timing Role: SN74HCT74PW functions as a parallel-output register - MCU writes data to D inputs, then pulses shared CLK to update all outputs simultaneously. Use Value: Enables atomic 2-bit output updates with no intermediate glitch states, critical for driving safety-critical actuators or display segments. |
| Digital Audio Clock Domain Crossing | Legacy Bus Interface Synchronization |
Use Scenario: Aligning asynchronous audio sample clocks (e.g., I²S bit clock vs. system master clock) to prevent buffer underruns/overruns in audio codecs. IC Role / Device Role / Timing Role: SN74HCT74PW serves as a 2-stage synchronizer - first stage captures metastable signal, second stage provides clean output aligned to destination clock domain. Use Value: Reduces metastability failure probability to <1e−9 per sample using proven 2FF synchronizer topology with verified setup/hold margins. |
Use Scenario: Interfacing modern microcontrollers with legacy parallel buses (e.g., 8080-style control signals) requiring precise strobe timing relative to address/data validity windows. IC Role / Device Role / Timing Role: SN74HCT74PW generates synchronized WR or RD strobes - D input driven by MCU, CLK tied to system clock, PRE/CLR manage bus turnaround delays. Use Value: Replaces discrete glue logic (AND/OR gates + RC delays) with single IC, shrinking BOM and improving timing repeatability across temperature. |
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 |
|---|---|---|---|
| SN74HCT74PWR | Same silicon die, identical AC/DC specs, TSSOP-14 package, lead finish NIPDAU/SN, MSL Level-1. | No functional difference; differs only in tape-and-reel packaging (2000 pcs/reel vs. obsolete PW variant). | Select SN74HCT74PWR for new designs - active status, full production support, and guaranteed long-term availability. |
| 74LVC74AD,118 | Lower VCC range (1.65–3.6 V), higher speed (tpd = 4.2 ns typ @ 3.3 V), but not TTL-compatible (VIH = 0.7×VCC). | Requires level translation when interfacing with 5-V TTL systems; unsuitable for direct drop-in replacement in legacy 5-V designs. | Choose 74LVC74AD,118 only for new 3.3-V systems prioritizing speed and power over backward compatibility. |
Compared with SN74HCT74PW, SN74HCT74PWR offers identical functionality with assured supply continuity, while 74LVC74AD,118 enables higher-speed 3.3-V operation but mandates redesign for voltage translation and timing validation.
Availability
SN74HCT74PW is available at Aetrix Electronics and suitable for industrial control, embedded instrumentation, and legacy system repair requiring stable component supply under extended lifecycle management.
Supply support for SN74HCT74PW 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 industrial, automotive, and communications markets.
The SN74HCT74PW belongs to TI's 74HCT logic family, designed specifically to bridge TTL and CMOS systems by combining TTL input thresholds with CMOS power efficiency and noise immunity for mixed-voltage board-level integration.
FAQ
What is the maximum clock frequency supported by the SN74HCT74PW?
The SN74HCT74PW supports up to 24 MHz maximum clock frequency at 5.5 V supply, derived from its 18 ns maximum propagation delay (tpd) and required setup/hold timing margins. This value is validated across the full operating temperature range (–40°C to +85°C) per TI's SCLS169G datasheet Section 5.5.
Does the SN74HCT74PW require external pull-up resistors on PRE and CLR pins?
No, the SN74HCT74PW does not require external pull-up resistors on PRE or CLR pins when actively driven - its inputs draw ≤1 μA, allowing direct connection to MCU GPIO or logic gates. However, if left unconnected, PRE and CLR must be tied to VCC via 10-kΩ resistors to prevent floating and unintended triggering, per TI application guidance.
Can the SN74HCT74PW operate reliably at 3.3 V supply?
No, the SN74HCT74PW is not specified for 3.3 V operation. Its recommended supply range is strictly 4.5 V to 5.5 V per Section 5.2 of the datasheet. At 3.3 V, input thresholds (VIH = 2 V, VIL = 0.8 V) become non-compliant, and output drive degrades below specification - use 74LVC74AD,118 instead for 3.3-V systems.
What is the thermal resistance (RθJA) of the SN74HCT74PW package?
The junction-to-ambient thermal resistance (RθJA) of the SN74HCT74PW in its TSSOP-14 package is 114.7 °C/W, measured under standard JEDEC JESD51-2 conditions with 1-inch² copper pad. This value is critical for calculating maximum allowable power dissipation in enclosed or high-temperature environments.
Is the SN74HCT74PW pin-compatible with other 74xx74 variants like SN74HC74 or SN74LS74?
The SN74HCT74PW shares identical pinout (TSSOP-14) and function table with SN74HC74 and SN74LS74, but is not electrically pin-compatible due to differing input thresholds and output drive. SN74HCT74PW accepts TTL-level inputs (VIH = 2 V), whereas SN74HC74 requires CMOS-level inputs (VIH ≈ 3.5 V at 5 V), making direct substitution unsafe without verification.
SN74HCT74PW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 14-TSSOP (0.173", 4.40mm 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:
- 46 MHz
- Max Propagation Delay @ V, Max CL:
- 25ns @ 5.5V, 50pF
- Trigger Type:
- Positive Edge
- Current - Output High, Low:
- 4mA, 4mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Current - Quiescent (Iq):
- 4 µA
- Input Capacitance:
- 3 pF
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-TSSOP
SN74HCT74PW FAQ
1.How can I place an order for SN74HCT74PW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCT74PW 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 SN74HCT74PW reliable?
The price and inventory of SN74HCT74PW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCT74PW is usually 5 days.
3.What payment methods are accepted for SN74HCT74PW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HCT74PW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HCT74PW?
SN74HCT74PW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCT74PW 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 SN74HCT74PW?
For technical support, including SN74HCT74PW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCT74PW requirements.
6.How does Aetrix verify that SN74HCT74PW is sourced from the original manufacturer or authorized distributors?
All SN74HCT74PW 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 SN74HCT74PW meets industry standards.
7.What is the process for return or replacement of SN74HCT74PW?
All SN74HCT74PW units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCT74PW, 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 SN74HCT74PW part is unused and in its original packaging.
Return procedure for SN74HCT74PW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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