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Texas Instruments SN74HCT574NG4
- Part No.:
- SN74HCT574NG4
- Manufacturer:
- Texas Instruments
- Category:
- Flip Flops
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74HCT574NG4.pdf
- Description:
- IC FF D-TYPE SNGL 8BIT 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,547
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Product details
Overview
SN74HCT574NG4 from Texas Instruments is an octal edge-triggered D-type flip-flop with 3-state noninverting outputs, designed for bus interface and data latching in 5V digital systems. It operates from 4.5V to 5.5V, delivers ±6mA output drive, exhibits 22ns typical propagation delay (tpd), and consumes ≤80μA ICC at 5.5V - enabling reliable register buffering in microcontroller I/O expansion and bidirectional data bus control.
For engineers reviewing the SN74HCT574NG4 datasheet, SN74HCT574NG4 pinout, SN74HCT574NG4 application, or SN74HCT574NG4 equivalent, key selection criteria include its TTL-compatible inputs, bus-structured 20-pin PDIP package, 3-state output enable timing (ten/tdis ≤45ns at CL=50pF), and compatibility with LSTTL load driving (up to 15 loads).
Technical Context
This device implements eight independent D-type flip-flops, each triggered on the low-to-high clock (CLK) transition. Data is latched synchronously, while dual output-enable inputs (1OE and 2OE) independently control two groups of four outputs each into high-impedance or active states - supporting bidirectional bus arbitration without affecting internal register state.
The logic family is HCT (High-Speed CMOS with TTL input thresholds), ensuring direct interfacing with legacy TTL systems. Input leakage is limited to ±1μA max, and outputs maintain VOH ≥3.7V and VOL ≤0.33V at 6mA drive under 4.5V–5.5V supply, meeting standard 5V logic level requirements for noise margin and fanout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5V to 5.5V - ensures interoperability with standard 5V TTL and CMOS systems without level shifting. |
| Propagation Delay (tpd) | 22ns typical at VCC=5V, CL=50pF - supports 24MHz maximum clock frequency in bus-holding applications. |
| Output Drive | ±6mA at VCC=5V - directly drives up to 15 LSTTL loads without external buffers. |
| Input Compatibility | TTL-voltage compatible (VIH=2V, VIL=0.8V) - accepts standard TTL logic levels without translation circuitry. |
| Quiescent Current (ICC) | ≤80μA max at VCC=5.5V - enables low-static-power operation in always-on register stages. |
| 3-State Enable Timing | ten ≤45ns, tdis ≤45ns at CL=50pF - guarantees fast bus release and acquisition for time-critical multiplexing. |
| Operating Temperature | −40°C to +85°C - qualified for industrial-grade embedded control and instrumentation environments. |
Pinout & Package
SN74HCT574NG4 is supplied in a 20-pin plastic dual in-line package (PDIP, N package), body size 24.33mm × 6.35mm, height ≤5.33mm. Pin 1 is index-marked; pin 10 is GND; pin 20 is VCC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 2OE | Active-low output enable inputs | Independently disable Q1–Q4 (1OE) or Q5–Q8 (2OE) to high-impedance; no effect on internal latch state. |
| CLK | Clock input | Edge-triggered on rising transition; all eight D inputs sampled and latched simultaneously. |
| D1–D8 | Data inputs | Asynchronous inputs feeding respective D-type flip-flop stages; TTL-compatible voltage thresholds. |
| Q1–Q8 | 3-state noninverting outputs | Drive bus lines directly; enter high-Z when corresponding OE is high, preserving bus integrity. |
| VCC, GND | Power supply terminals | Single 5V supply rail; requires local 0.1μF bypass capacitor per device for stable switching noise suppression. |
Key Features
| Feature | Design Value |
|---|---|
| Bus-structured pinout | Alternating I/O layout (e.g., D1–Q1–D2–Q2…) minimizes trace crosstalk and simplifies PCB routing for parallel data buses. |
| High-current 3-state outputs | ±6mA drive capability allows direct connection to unterminated bus traces or legacy LSTTL loads without pull-ups or drivers. |
| Low input current | ≤1μA max input leakage reduces loading on upstream logic and enables clean signal integrity in high-fanout configurations. |
| Independent dual OE control | Two separate output-enable pins support split-bus architectures (e.g., upper/lower byte control) without additional logic gates. |
| TTL-compatible inputs | VIH = 2V / VIL = 0.8V thresholds ensure seamless integration with 74LS, 74F, and other TTL families without level shifters. |
Applications
| Microcontroller I/O Expansion | Parallel Bus Interface |
|---|---|
Use Scenario: Expanding GPIO count of an MCU by adding 8-bit bidirectional data latches connected to address/data multiplexed buses. IC Role / Device Role / Timing Role: Acts as an output register (latching MCU data) and input buffer (capturing peripheral status), synchronized to MCU WR/RD strobes. Use Value: Enables deterministic 8-bit parallel communication with peripherals such as LCD controllers or ADCs using minimal MCU pins and no software bit-banging overhead. |
Use Scenario: Isolating and latching data between two asynchronous 8-bit bus domains (e.g., CPU bus ↔ FPGA configuration bus). IC Role / Device Role / Timing Role: Functions as a transparent, edge-triggered data bridge with independent OE control for direction management and bus contention avoidance. Use Value: Eliminates need for discrete transceivers or complex glue logic; supports hot-swap-safe bus arbitration via fast 3-state enable/disable (≤45ns). |
| Industrial Digital I/O Module | Legacy System Bus Buffering |
Use Scenario: Building ruggedized PLC I/O modules where field sensors/actuators connect to isolated 5V logic via optocouplers and latch registers. IC Role / Device Role / Timing Role: Serves as a noise-immune input capture register and output drive stage, decoupling slow field-side timing from fast controller clocks. Use Value: Provides robust 8-bit parallel data staging with ±6mA drive and 85°C operation, meeting industrial environmental and EMI immunity requirements. |
Use Scenario: Interfacing modern microcontrollers to vintage 8-bit computer buses (e.g., Z80, 6502) requiring TTL-level latching and bus driving. IC Role / Device Role / Timing Role: Emulates original 74LS374 behavior with identical pinout and timing margins, acting as drop-in replacement for aging components. Use Value: Restores system reliability with improved DC specs (lower ICC, tighter VOH/VOL) and extended temperature range versus obsolete bipolar TTL parts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal D-type latch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT374N | Same HCT family, identical 20-pin PDIP package, but features single shared OE (not dual OE); otherwise matching tpd, drive, and voltage specs. | Lacks independent upper/lower byte control; suitable only for full-bus (8-bit) enable, not split-bus architectures. | Select SN74HCT374N when simplified OE logic suffices and board layout rework for dual-OE signals is undesirable. |
| 74ACT574PC | ACT family: higher speed (tpd ≈10ns), wider VCC range (4.5–5.5V), but higher ICC (≤4mA) and less noise margin (VIH=3.5V). | Requires stricter power delivery and noise control; incompatible with TTL input sources due to higher VIH threshold. | Choose 74ACT574PC only when sub-12ns timing is mandatory and system-level noise immunity has been verified. |
Compared with SN74HCT574NG4, SN74HCT374N simplifies control logic at the cost of bus segmentation flexibility, while 74ACT574PC trades power efficiency and TTL compatibility for raw speed - making SN74HCT574NG4 optimal for industrial 5V bus interfaces requiring robustness, low static power, and legacy compatibility.
Availability
SN74HCT574NG4 is available at Aetrix Electronics and suitable for microcontroller I/O expansion, parallel bus interface, and industrial digital I/O modules requiring stable component supply across long-lifecycle embedded programs.
Supply support for SN74HCT574NG4 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 electronics.
SN74HCT574NG4 belongs to TI's legacy 74HCT logic family, engineered for pin- and function-compatible upgrades of 74LS devices in 5V systems - emphasizing interoperability, low power, and industrial temperature resilience.
FAQ
What is the operating voltage range for SN74HCT574NG4?
The SN74HCT574NG4 operates from 4.5V to 5.5V. This range ensures compatibility with standard 5V TTL and CMOS logic families while maintaining specified timing and drive performance. Operation outside this range may cause functional failure or damage; absolute maximum supply voltage is 7V.
Does SN74HCT574NG4 support bidirectional data flow?
SN74HCT574NG4 does not perform bidirectional data transfer internally, but enables bidirectional bus operation externally via its dual 3-state output enables (1OE and 2OE). When used with complementary control logic, it can isolate and latch data in either direction on a shared bus - a common implementation in microcontroller peripheral interfacing.
What is the maximum clock frequency supported by SN74HCT574NG4?
SN74HCT574NG4 supports a maximum clock frequency of 24MHz at VCC = 4.5V and TA = 85°C (per recommended operating conditions). At 5.5V and 25°C, fmax reaches 27MHz. These values assume CL = 50pF; heavier capacitive loads reduce achievable frequency due to increased tpd.
How does the dual output-enable feature of SN74HCT574NG4 improve system design?
The dual OE inputs (1OE and 2OE) in SN74HCT574NG4 allow independent control of two 4-bit output groups (Q1–Q4 and Q5–Q8). This enables byte-level bus partitioning - for example, managing upper/lower memory addresses or separating control/status signals - without external gating logic, reducing component count and PCB area.
Is SN74HCT574NG4 pin-compatible with older 74LS374 devices?
Yes, SN74HCT574NG4 is pin-compatible and functionally equivalent to 74LS374 in 20-pin PDIP packaging, including identical pin assignments for CLK, Dn, Qn, OE, VCC, and GND. However, SN74HCT574NG4 offers lower ICC (80μA vs. ~25mA), tighter VOH/VOL, and improved noise immunity - making it a direct, drop-in power- and performance-enhanced replacement.
SN74HCT574NG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Discontinued at Digi-Key
- Function:
- Standard
- Type:
- D-Type
- Output Type:
- Tri-State, Non-Inverted
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Clock Frequency:
- 40 MHz
- Max Propagation Delay @ V, Max CL:
- 47ns @ 5.5V, 150pF
- Trigger Type:
- Positive Edge
- Current - Output High, Low:
- 6mA, 6mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Current - Quiescent (Iq):
- 8 µA
- Input Capacitance:
- 3 pF
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74HCT574NG4 FAQ
1.How can I place an order for SN74HCT574NG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCT574NG4 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 SN74HCT574NG4 reliable?
The price and inventory of SN74HCT574NG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCT574NG4 is usually 5 days.
3.What payment methods are accepted for SN74HCT574NG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HCT574NG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HCT574NG4?
SN74HCT574NG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCT574NG4 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 SN74HCT574NG4?
For technical support, including SN74HCT574NG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCT574NG4 requirements.
6.How does Aetrix verify that SN74HCT574NG4 is sourced from the original manufacturer or authorized distributors?
All SN74HCT574NG4 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 SN74HCT574NG4 meets industry standards.
7.What is the process for return or replacement of SN74HCT574NG4?
All SN74HCT574NG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCT574NG4, 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 SN74HCT574NG4 part is unused and in its original packaging.
Return procedure for SN74HCT574NG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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