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Texas Instruments SN74LS374DBR
- Part No.:
- SN74LS374DBR
- Manufacturer:
- Texas Instruments
- Category:
- Flip Flops
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74LS374DBR.pdf
- Description:
- IC FF D-TYPE SNGL 8BIT 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,123
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Product details
Overview
SN74LS374DBR from Texas Instruments is an octal positive-edge-triggered D-type flip-flop with 3-state bus-driver outputs, designed for synchronous data latching in TTL-compatible digital systems. It features clock-enable input with hysteresis (improving noise rejection by ~400 mV), buffered control inputs, and full parallel access - enabling reliable use in address/data bus interfaces, I/O port expansion, and register file implementations.
For engineers reviewing the SN74LS374DBR datasheet, SN74LS374DBR pinout, SN74LS374DBR application, or SN74LS374DBR equivalent, this device is selected for high-reliability 8-bit edge-triggered storage where bus isolation, low propagation delay (15–28 ns), and industrial-temperature operation (0°C to 70°C) are required in legacy or mixed-logic designs.
Technical Context
The SN74LS374DBR implements eight independent D-type flip-flops, each triggered on the rising edge of CLK. Its output-control (OC) input operates independently of internal state, allowing high-impedance output disable without affecting stored data or latch timing.
It uses standard TTL input thresholds (VIH = 2.0 V, VIL = 0.8 V), supports 24 mA sink current per output, and maintains compatibility with LS-family logic levels and drive strength. The SSOP-20 package enables compact board layout while retaining full pin compatibility with other 'LS374 variants in DW/N/NS packages.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | TTL LS (Low-power Schottky) - ensures compatibility with legacy 5 V TTL systems and predictable noise margins. |
| Function | Octal D-type positive-edge-triggered flip-flop - stores 8 bits synchronously on CLK rising edge, not transparent like latches. |
| Output Type | 3-state (tri-state) bus-driving outputs - enables direct connection to shared data/address buses without external pull-ups or interface logic. |
| Max Clock Frequency | 50 MHz (RL = 667 Ω, CL = 45 pF) - supports high-speed bus handshaking in industrial control and instrumentation. |
| Propagation Delay | tPLH/tPHL = 15–28 ns (CLK to Q) - ensures tight timing budgets in synchronous register-to-bus transfer paths. |
| Supply Voltage | VCC = 4.75 V to 5.25 V - requires stable 5 V rail; absolute max 7 V prevents damage during transient overvoltage. |
| IOL / IOH | 24 mA sink / –2.6 mA source per output - drives standard TTL loads directly; sufficient for multiple LS inputs or small capacitive buses. |
Pinout & Package
SN74LS374DBR is housed in a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, optimized for space-constrained PCBs while maintaining thermal performance (θJA = 70°C/W). Pin numbering follows standard TI top-view orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | OC (Output Control) | Active-low enable for all 3-state outputs; does not affect internal flip-flop state or clocking behavior. |
| 2–9 | D1–D8 (Data Inputs) | Asynchronous parallel data inputs; sampled on rising CLK edge and latched into respective flip-flops. |
| 10 | GND | Ground reference for all logic and power connections; must be low-impedance for noise immunity. |
| 11–18 | Q1–Q8 (Outputs) | 3-state outputs reflecting stored D-input values; high-impedance when OC = HIGH. |
| 19 | CLK | Clock input with Schmitt-trigger hysteresis (~400 mV); ensures clean edge detection despite slow-rising or noisy clock signals. |
| 20 | VCC | +5 V supply; decoupling capacitor (0.1 µF ceramic) required near pin for stable switching operation. |
Key Features
| Feature | Design Value |
|---|---|
| Positive-edge-triggered flip-flops | Ensures deterministic sampling of D inputs only at CLK rising edges - eliminates metastability risks from asynchronous enable schemes. |
| 3-state bus-driving outputs | Enables direct connection to bidirectional data buses without external transceivers or pull-up resistors, reducing component count and layout complexity. |
| Buffered OC and CLK inputs | Reduces loading on upstream drivers and improves fan-out capability - supports driving multiple SN74LS374DBR devices from one controller output. |
| Hysteresis on CLK input | Improves noise immunity by ~400 mV threshold separation - critical for robust operation in electrically noisy industrial environments. |
| Full parallel load architecture | Allows simultaneous capture of 8-bit data across all flip-flops, supporting fast register updates in microprocessor peripheral interfaces. |
Applications
| Microprocessor Address Latch | Industrial I/O Port Expansion |
|---|---|
|
Use Scenario: Latching 8-bit address or data bus segments in 8080/Z80-based embedded controllers where memory-mapped peripherals require stable address lines during read/write cycles. IC Role / Device Role / Timing Role: Edge-triggered storage element capturing bus data on CPU ALE-equivalent signal (CLK), with OC tied to chip-select decoding for bus isolation. Use Value: Eliminates need for discrete gating logic; provides guaranteed setup/hold times (tsu = 20 ns, th = 5 ns) compatible with legacy CPU timing specifications. |
Use Scenario: Expanding GPIO capability in PLC modules or CNC motion controllers using parallel bus interfaces with isolated signal domains. IC Role / Device Role / Timing Role: Bidirectional data register buffering between microcontroller and field-side opto-isolated inputs/outputs, controlled via OC and CLK from system bus. Use Value: 24 mA sink capability drives LED indicators or relay drivers directly; 3-state outputs prevent contention during bus arbitration. |
| Legacy Bus Interface Bridge | Test Equipment Data Capture |
|
Use Scenario: Interfacing modern FPGA-based test fixtures to vintage TTL backplanes (e.g., IEEE-488 GPIB auxiliary lines or VMEbus data lanes). IC Role / Device Role / Timing Role: Synchronizing asynchronous bus transactions using CLK derived from FPGA clock domain, with OC managed by state machine for bus ownership control. Use Value: Matches LS-family voltage thresholds and drive strength - avoids level-shifter requirements and preserves signal integrity on long traces. |
Use Scenario: Capturing parallel sensor output streams (e.g., 8-channel ADC results) in automated test equipment requiring precise timestamp alignment. IC Role / Device Role / Timing Role: Simultaneous sampling node triggered by precision clock generator; outputs fed to FIFO or microcontroller DMA channel via shared data bus. Use Value: 15–28 ns CLK-to-Q delay enables sub-35 ns sampling resolution; low skew across all 8 channels ensures coherent multi-channel acquisition. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal D-type flip-flop applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS374DWR | Same logic function and electrical specs; packaged in SOIC-20 (DW) instead of SSOP-20 (DB). Slightly higher θJA (58°C/W vs. 70°C/W) but larger footprint. | Better thermal dissipation in high-density layouts; preferred where reflow profile or board assembly constraints favor SOIC over SSOP. | Select SN74LS374DWR if board real estate allows larger package and thermal management is prioritized over miniaturization. |
| SN74LS374N | Identical functionality and timing; PDIP-20 package with through-hole mounting. Higher θJA (69°C/W), no RoHS exemption, and larger board area requirement. | Suitable for prototyping, repair, or legacy through-hole manufacturing; incompatible with fine-pitch SMT assembly lines. | Choose SN74LS374N only for hand-soldered prototypes, educational labs, or backward-compatible replacements in existing through-hole designs. |
Compared with SN74LS374DWR and SN74LS374N, the SN74LS374DBR offers the smallest PCB footprint among 'LS374 variants while maintaining identical timing, drive strength, and logic behavior - making it optimal for space-constrained industrial and instrumentation PCBs requiring surface-mount reliability.
Availability
SN74LS374DBR is available at Aetrix Electronics and suitable for industrial control systems, legacy test equipment upgrades, and embedded microprocessor peripheral interfaces requiring stable component supply and long-term obsolescence support.
Supply support for SN74LS374DBR 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 with over 90 years of analog and logic IC innovation, serving industrial, automotive, and communications markets.
The SN74LS374DBR belongs to TI's classic 74LS logic family, engineered for robust 5 V TTL interoperability, noise-immune clocking, and bus-oriented 3-state operation in mission-critical industrial and instrumentation applications.
FAQ
What is the primary function of the SN74LS374DBR?
The SN74LS374DBR is an octal positive-edge-triggered D-type flip-flop with 3-state outputs. It captures and holds 8 bits of data on the rising edge of its CLK input, and its OC pin controls whether outputs drive the bus or enter high-impedance mode - making it ideal for synchronous bus interfacing in legacy TTL systems.
Does the SN74LS374DBR support 3.3 V operation?
No, the SN74LS374DBR is specified only for 4.75 V to 5.25 V VCC operation. It is not 3.3 V tolerant: applying 3.3 V violates the minimum VIH (2.0 V) and VIL (0.8 V) thresholds, and may cause unreliable switching or increased ICC. Use 74LVC or 74ALVC series for true 3.3 V compatibility.
How does the hysteresis on the CLK input benefit the SN74LS374DBR?
The CLK input of the SN74LS374DBR incorporates Schmitt-trigger hysteresis (~400 mV), which raises the effective VIH and lowers the effective VIL compared to standard TTL inputs. This improves noise rejection in electrically noisy environments - such as motor drives or industrial PLCs - preventing false clock triggering from slow edges or EMI-induced glitches.
Can the SN74LS374DBR replace the SN74LS373 in a design?
No - the SN74LS374DBR is an edge-triggered flip-flop, while the SN74LS373 is a transparent latch. Their timing behaviors differ fundamentally: the '373 passes D to Q while C is high, whereas the '374 samples D only on CLK rising edge. Substituting them requires redesigning clocking and control logic to avoid data corruption.
What is the maximum capacitive load the SN74LS374DBR can drive reliably?
The SN74LS374DBR is characterized for RL = 667 Ω and CL = 45 pF in switching tests, achieving 50 MHz max frequency under those conditions. Driving >45 pF increases propagation delay and reduces noise margin; for heavier loads, add series termination or buffer stages. Always verify timing margins with actual board-level capacitance measurements.
SN74LS374DBR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LS
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Standard
- Type:
- D-Type
- Output Type:
- Tri-State, Non-Inverted
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Clock Frequency:
- 50 MHz
- Max Propagation Delay @ V, Max CL:
- 28ns @ 5V, 45pF
- Trigger Type:
- Positive Edge
- Current - Output High, Low:
- 2.6mA, 24mA
- Voltage - Supply:
- 4.75V ~ 5.25V
- Current - Quiescent (Iq):
- 40 mA
- Input Capacitance:
- -
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74LS374DBR FAQ
1.How can I place an order for SN74LS374DBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS374DBR 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 SN74LS374DBR reliable?
The price and inventory of SN74LS374DBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS374DBR is usually 5 days.
3.What payment methods are accepted for SN74LS374DBR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS374DBR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS374DBR?
SN74LS374DBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS374DBR 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 SN74LS374DBR?
For technical support, including SN74LS374DBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS374DBR requirements.
6.How does Aetrix verify that SN74LS374DBR is sourced from the original manufacturer or authorized distributors?
All SN74LS374DBR 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 SN74LS374DBR meets industry standards.
7.What is the process for return or replacement of SN74LS374DBR?
All SN74LS374DBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS374DBR, 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 SN74LS374DBR part is unused and in its original packaging.
Return procedure for SN74LS374DBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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