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Texas Instruments SN74ALS876ADW
- Part No.:
- SN74ALS876ADW
- Manufacturer:
- Texas Instruments
- Category:
- Flip Flops
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS876ADW.pdf
- Description:
- IC FF D-TYPE DUAL 4BIT 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,393
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Product details
Overview
SN74ALS876ADW from Texas Instruments is a dual 4-bit D-type edge-triggered flip-flop with inverting 3-state outputs, designed as a bus-oriented register for bidirectional data flow control. It features asynchronous preset (PRE) inputs, true bus-structured pinout, and operates at up to 30 MHz clock frequency across 0°C to 70°C. It is used in I/O port expansion and buffered address/data latching in legacy industrial control systems.
For engineers reviewing the SN74ALS876ADW datasheet, SN74ALS876ADW pinout, SN74ALS876ADW application, or SN74ALS876ADW equivalent, key selection factors include its inverting Q outputs, 24-pin SOIC (DW) package, 30 MHz max clock rate, 24 mA low-level output drive, and compatibility with ALS logic family voltage thresholds.
Technical Context
This device implements two independent 4-bit D-type registers, each with separate clock (CLK), preset (PRE), and output-enable (OE) controls. Data is latched on the low-to-high transition of CLK; asserting PRE low forces all four corresponding Q outputs low regardless of clock state.
The 3-state outputs support direct bus driving with bus-structured pinout (e.g., Q1–Q4 adjacent), and the ALS process ensures TTL-compatible input thresholds (VIH = 2 V min, VIL = 0.8 V max) and robust noise immunity at 5 V supply.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | Advanced Low-Power Schottky (ALS), compatible with TTL voltage levels and drive requirements |
| Function | Dual 4-bit edge-triggered D flip-flop with inverting Q outputs and asynchronous PRE |
| Max Clock Frequency | 30 MHz - supports high-speed synchronous data capture in legacy backplane interfaces |
| Output Drive | IOL = 24 mA (min) - sufficient to drive multiple TTL loads or terminated bus lines directly |
| Supply Voltage | VCC = 4.5 V to 5.5 V - operates reliably across standard 5 V rail tolerances |
| Operating Temperature | 0°C to 70°C - qualified for commercial/industrial ambient environments |
| Propagation Delay | tPLH/tPHL ≤ 14 ns (max) - enables tight timing margins in synchronous register chains |
Pinout & Package
SN74ALS876ADW uses a 24-pin SOIC (DW) package with 300-mil width, gull-wing leads, and JEDEC MS-013AC outline. Pin 1 is located at the top-left corner with notch or index mark orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 13, 23 | PRE, OE, CLK (Channel 1) | Asynchronous preset (active-low), output enable (active-low), and clock (edge-triggered) for first 4-bit register |
| 2–6, 19–22 | D1–D4, Q1–Q4 (Channel 1) | Data inputs and inverted registered outputs for first 4-bit section; Q outputs are active-low when enabled |
| 11, 14, 24 | CLK, OE, PRE (Channel 2) | Independent clock, output enable, and preset for second 4-bit register |
| 7–10, 15–18 | D1–D4, Q1–Q4 (Channel 2) | Data inputs and inverted registered outputs for second 4-bit section; fully isolated timing control |
| 12, 24 | GND, VCC | Power return and +5 V supply pins placed for low-inductance decoupling near register clusters |
Key Features
| Feature | Design Value |
|---|---|
| Inverting 3-state outputs | Enables bidirectional bus arbitration without external inverters; Q outputs go high-impedance when OE is high |
| Bus-structured pinout | Adjacent Q1–Q4 and D1–D4 pins simplify PCB routing for parallel data buses and reduce trace skew |
| Asynchronous preset (PRE) | Allows immediate initialization of all four Q outputs to low state independent of clock, critical for power-up reset |
| ALS logic performance | Combines 30 MHz speed with 24 mA drive and low ICC (31 mA max, all outputs disabled) for balanced speed/power |
| TTL-compatible interface | Accepts standard TTL VIH/VIL thresholds and drives TTL/ALS loads directly-no level-shifting required |
Applications
| Industrial I/O Expansion | Legacy Backplane Interface |
|---|---|
Use Scenario: Adding parallel digital I/O capability to PLC mainframes using ISA-style or custom 8/16-bit bus architectures. IC Role / Device Role / Timing Role: Acts as an output latch and input buffer register, synchronizing host CPU writes/reads with field-device timing via dedicated PRE and CLK signals. Use Value: Eliminates need for discrete inverters and tristate buffers; single SN74ALS876ADW handles 8-bit bidirectional port control with deterministic setup/hold timing. | Use Scenario: Interfacing microprocessor-based controllers to legacy instrumentation modules with shared address/data buses. IC Role / Device Role / Timing Role: Serves as a buffered address latch and data transceiver, isolating CPU timing from slower peripheral response using OE-controlled 3-state outputs. Use Value: Enables clean bus turnaround with <14 ns propagation delay and <13 ns output disable time, preventing bus contention during direction switching. |
| Test Equipment Control Logic | Avionics Maintenance Interface |
Use Scenario: Implementing programmable signal routing and pattern generation in automated test equipment (ATE) rack controllers. IC Role / Device Role / Timing Role: Functions as a synchronous pattern register, capturing stimulus vectors on CLK edges and holding stable outputs until next load cycle. Use Value: PRE input allows instant vector reset before test sequence start; 24 mA drive ensures reliable signaling across long backplane traces with 50 pF loading. | Use Scenario: Supporting ground-based diagnostics for older avionics subsystems requiring discrete logic-based communication handshaking. IC Role / Device Role / Timing Role: Provides deterministic, radiation-tolerant (via design heritage) register staging between MIL-STD-1553 bus controllers and local sensor interfaces. Use Value: ALS process delivers proven reliability in temperature-cycled environments; bus-structured pinout simplifies conformal coating and inspection of critical signal groups. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual 4-bit bus register applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS874BDW | Non-inverting Q outputs; CLR (not PRE) input; otherwise identical pinout, timing, and drive | Requires external inversion for active-low bus signaling; preferred where output polarity must match upstream logic | Select SN74ALS874BDW when non-inverting register behavior aligns with system-level signal conventions |
| SN74AS876DW | Faster (80 MHz max), higher drive (48 mA IOL), but higher ICC (160 mA max) and AS-family input thresholds (VIL = 0.8 V only) | Suitable for speed-critical upgrades; requires verification of input noise margin due to reduced VIL hysteresis | Choose SN74AS876DW only when 30+ MHz operation is mandatory and power budget permits ~5× higher quiescent current |
Compared with SN74ALS876ADW, SN74ALS874BDW offers identical timing and packaging but inverted functionality logic, while SN74AS876DW trades power efficiency for raw speed-neither is pin-compatible without board-level redesign due to differing PRE/CLR pin assignments and electrical thresholds.
Availability
SN74ALS876ADW is available at Aetrix Electronics and suitable for industrial I/O expansion, legacy backplane interface, and test equipment control applications requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS876ADW 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74ALS876ADW belongs to TI's legacy ALS logic portfolio, engineered for high-reliability, medium-speed bus interfacing in systems where compatibility with 1980s–1990s TTL infrastructure remains essential.
FAQ
What is the function of the PRE pin on the SN74ALS876ADW?
The PRE (preset) pin on the SN74ALS876ADW is an active-low asynchronous control that forces all four Q outputs of its associated 4-bit register to logic low, independent of the clock signal. This provides immediate initialization capability during power-up or fault recovery. For SN74ALS876ADW, both register sections have dedicated PRE inputs (pins 1 and 24), enabling independent reset of each 4-bit group without affecting the other.
Does the SN74ALS876ADW support hot-swap or live-insertion?
No, the SN74ALS876ADW does not support hot-swap or live-insertion. Its absolute maximum ratings specify no protection against supply sequencing violations or I/O pin biasing prior to VCC stabilization. Applying signals to inputs or outputs before VCC reaches ≥4.5 V risks latch-up or permanent damage. System designs using SN74ALS876ADW must ensure proper power-rail ramp-up order and avoid floating inputs during insertion.
What is the recommended bypass capacitor value for the SN74ALS876ADW?
The recommended bypass capacitor for the SN74ALS876ADW is a 0.1 µF ceramic capacitor placed as close as possible to the VCC (pin 24) and GND (pin 12) pins. This value suppresses high-frequency switching noise generated by the 24 mA output transitions and maintains stable internal node voltages. For systems with heavy bus loading or long traces, adding a 4.7 µF tantalum capacitor nearby improves low-frequency decoupling and reduces supply droop during simultaneous output switching.
Can the SN74ALS876ADW be used with a 3.3 V microcontroller interface?
No, the SN74ALS876ADW cannot be directly interfaced with a 3.3 V microcontroller without level translation. Its input thresholds require VIH ≥ 2.0 V and VIL ≤ 0.8 V at VCC = 5 V, making it incompatible with 3.3 V logic high levels (typically 2.4–3.3 V). Driving SN74ALS876ADW inputs from a 3.3 V source risks marginal or incorrect recognition of logic high states. A dedicated level shifter or buffer such as SN74LVC4245A is required for safe interoperability.
How does the SN74ALS876ADW differ from the SN74AS876DW in terms of timing behavior?
The SN74ALS876ADW has a maximum clock frequency of 30 MHz and propagation delays up to 14 ns, while the SN74AS876DW supports 80 MHz operation with delays as low as 3 ns (tPLH min). The AS version also exhibits faster enable/disable times (e.g., tPHZ ≤ 7 ns vs. 10 ns) but consumes significantly more supply current (160 mA max vs. 31 mA). These differences reflect the AS family's speed-optimized bipolar process versus the ALS family's balanced speed-power trade-off in the SN74ALS876ADW.
SN74ALS876ADW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Master Reset
- Type:
- D-Type
- Output Type:
- Tri-State, Inverted
- Number of Elements:
- 2
- Number of Bits per Element:
- 4
- Clock Frequency:
- 30 MHz
- Max Propagation Delay @ V, Max CL:
- 14ns @ 5V, 50pF
- Trigger Type:
- Positive Edge
- Current - Output High, Low:
- 2.6mA, 24mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Current - Quiescent (Iq):
- 21 mA
- Input Capacitance:
- -
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SOIC
SN74ALS876ADW FAQ
1.How can I place an order for SN74ALS876ADW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS876ADW 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 SN74ALS876ADW reliable?
The price and inventory of SN74ALS876ADW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS876ADW is usually 5 days.
3.What payment methods are accepted for SN74ALS876ADW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS876ADW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS876ADW?
SN74ALS876ADW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS876ADW 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 SN74ALS876ADW?
For technical support, including SN74ALS876ADW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS876ADW requirements.
6.How does Aetrix verify that SN74ALS876ADW is sourced from the original manufacturer or authorized distributors?
All SN74ALS876ADW 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 SN74ALS876ADW meets industry standards.
7.What is the process for return or replacement of SN74ALS876ADW?
All SN74ALS876ADW units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS876ADW, 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 SN74ALS876ADW part is unused and in its original packaging.
Return procedure for SN74ALS876ADW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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