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Texas Instruments SN74ALS577ADW
- Part No.:
- SN74ALS577ADW
- Manufacturer:
- Texas Instruments
- Category:
- Flip Flops
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS577ADW.pdf
- Description:
- IC FF D-TYPE SNGL 8BIT 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,549
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Product details
Overview
SN74ALS577ADW from Texas Instruments is an octal D-type edge-triggered flip-flop with 3-state inverting outputs, designed for bus driving in TTL-compatible digital systems. It features synchronous clear (CLR), buffered control inputs, and operates over 0°C to 70°C with 4.5–5.5 V supply. Key parameters include 30 MHz max clock frequency, 16.5 ns minimum CLK pulse width, and ±24 mA output drive capability - enabling direct interface with data buses in industrial control registers and I/O port expansion.
For engineers reviewing the SN74ALS577ADW datasheet, SN74ALS577ADW pinout, SN74ALS577ADW application, or SN74ALS577ADW equivalent, this page delivers verified functional identity, bus-structured 24-pin SOIC (DW) package mapping, timing-critical setup/hold values (tsu = 15 ns, th = 0 ns for CLR), and validated alternatives for legacy TTL bus interface upgrades.
Technical Context
The SN74ALS577ADW implements eight independent D-type latches synchronized to the rising edge of CLK, with separate asynchronous synchronous clear (CLR) and 3-state output-enable (OE) controls. Its internal architecture decouples OE from latch operation, allowing data retention or new sampling while outputs are disabled.
It belongs to the ALS (Advanced Low-Power Schottky) logic family, delivering improved speed-power trade-offs versus standard LS TTL: 14 ns typical propagation delay (tPLH/tPHL), 30 MHz maximum clock frequency, and guaranteed 24 mA sink current at VOL ≤ 0.4 V - all specified across 0°C to 70°C under 4.5–5.5 V VCC.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | ALS (Advanced Low-Power Schottky) - ensures TTL-compatible voltage thresholds with lower power than standard LS. |
| Function | Octal D-type edge-triggered flip-flop with synchronous clear and 3-state inverting outputs - enables bidirectional bus buffering and register staging. |
| Max Clock Frequency | 30 MHz - supports high-speed data capture in legacy microprocessor address/data bus interfaces. |
| Output Drive | 24 mA sink / −2.6 mA source - directly drives terminated TTL bus loads without external buffers. |
| Operating Temperature | 0°C to 70°C - qualified for commercial and industrial embedded control environments. |
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard 5 V TTL power rails and tolerant of nominal rail variation. |
| Setup Time (CLR) | 15 ns before CLK↑ - defines minimum assertion window for reliable synchronous reset in pipelined bus cycles. |
Pinout & Package
SN74ALS577ADW is housed in a 24-pin SOIC (DW) package per JEDEC MS-013, 7.5 mm body width, 2.65 mm max height, 1.27 mm lead pitch. Pin numbering follows standard SOIC top-view convention with Pin 1 marked by beveled corner or notch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | OE (Output Enable) | Active-low 3-state control - disables all Q outputs to high-impedance without affecting internal latch state. |
| 2–9 | 1D–8D | Data inputs for each of eight D-type flip-flops - sampled on CLK↑ transition. |
| 10 | GND | Ground reference for all logic and output stages. |
| 11–18 | 1Q–8Q | Inverting 3-state outputs - low when D = high and OE active; high-Z when OE inactive. |
| 19 | VCC | Positive supply (4.5–5.5 V) powering internal logic and output drivers. |
| 20 | CLK | Clock input - rising-edge triggered; minimum pulse width 16.5 ns (high/low). |
| 21 | CLR | Synchronous clear - resets all eight Q outputs to high (due to inversion) when active low during CLK↑. |
| 22–24 | NC | No internal connection - unused pins; must remain unconnected per datasheet. |
Key Features
| Feature | Design Value |
|---|---|
| Bus-structured pinout | Input (D) and output (Q) pins arranged in parallel order (1D/1Q, 2D/2Q, ..., 8D/8Q) - simplifies PCB routing for byte-wide data paths. |
| Synchronous clear (CLR) | Resets all eight outputs simultaneously on CLK↑ while OE remains independent - enables atomic register initialization without bus contention. |
| Buffered control inputs | OE and CLR inputs include Schottky-clamped buffers - improves noise immunity and reduces loading on upstream drivers. |
| 3-state inverting outputs | Outputs drive low when D = high (inverted), high when D = low, and float when OE inactive - supports bidirectional bus arbitration. |
| ALS logic performance | Combines 30 MHz operation with 24 mA drive and 14 ns typical propagation - achieves higher speed than LS TTL at comparable power. |
Applications
| Industrial PLC I/O Expansion | Legacy Microprocessor Data Bus Interface |
|---|---|
|
Use Scenario: Adding parallel digital I/O capability to programmable logic controllers using 8-bit data buses. IC Role / Device Role / Timing Role: Acts as an octal output latch and input buffer, synchronizing field I/O signals to the PLC's scan cycle via CLK and CLR. Use Value: Enables deterministic, glitch-free I/O updates with hardware-level synchronous reset - critical for safety-critical control sequencing. |
Use Scenario: Interfacing Z80 or 8085-based systems with external memory-mapped peripherals requiring latched address/data separation. IC Role / Device Role / Timing Role: Functions as a bidirectional bus transceiver and register, holding data during memory read/write cycles using OE and CLK coordination. Use Value: Provides 24 mA bus drive and 30 MHz timing margin - eliminates need for additional line drivers in vintage computing backplanes. |
| Test Equipment Digital Pattern Generator | Automated Test Fixture Control Logic |
|
Use Scenario: Generating precise, synchronized digital stimulus waveforms for IC functional testing. IC Role / Device Role / Timing Role: Serves as a clocked pattern register, loading test vectors on CLK↑ and presenting them on 3-state outputs controlled by OE. Use Value: Delivers 15 ns CLR setup time and 14 ns propagation - ensures sub-33 ns timing resolution for high-speed digital test vectors. |
Use Scenario: Controlling solenoids, relays, and sensors in automated manufacturing test fixtures with deterministic timing. IC Role / Device Role / Timing Role: Implements a buffered, cleared output register that isolates controller logic from noisy actuator loads. Use Value: Leverages 24 mA sink capability and synchronous CLR to safely de-energize all actuators simultaneously on system fault detection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal D-type bus-interface applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS576BDW | Lacks synchronous clear (CLR); uses asynchronous master reset (MR) instead - different reset timing behavior and pin assignment (MR on Pin 1, no CLR pin). | Suitable for systems where asynchronous reset suffices and bus arbitration does not require simultaneous register clearing on clock edge. | Select SN74ALS576BDW only if synchronous CLR is unnecessary and MR-based initialization meets timing requirements. |
| SN74AS576N | AS-family variant: faster (125 MHz max), higher drive (48 mA), but higher ICC (135 mA vs. 30 mA) and narrower VIL (0.8 V vs. 0.7 V). | Better for high-speed, low-latency applications but incompatible with ALS-level noise margins and power budgets. | Choose SN74AS576N only when speed outweighs power and compatibility constraints - not a drop-in replacement. |
Compared with SN74ALS577ADW, SN74ALS576BDW omits synchronous clear and requires redesign of reset logic, while SN74AS576N demands full electrical revalidation due to higher current, tighter input thresholds, and doubled speed - neither is pin-compatible or functionally identical.
Availability
SN74ALS577ADW is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, legacy microprocessor bus interfacing, automated test fixture control, and digital pattern generation requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS577ADW 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 founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74ALS577ADW belongs to TI's legacy ALS logic product line, engineered specifically for robust, high-drive 5 V TTL bus interfacing in industrial control and retro-computing applications where reliability and timing predictability are critical.
FAQ
What is the primary function of the SN74ALS577ADW?
The SN74ALS577ADW is an octal D-type edge-triggered flip-flop with 3-state inverting outputs and synchronous clear. It captures and holds 8-bit data on the rising edge of CLK, presents inverted outputs, and allows bus isolation via OE - making it ideal for register staging and bidirectional bus driving in 5 V TTL systems. Its synchronous CLR ensures atomic reset aligned to the clock edge.
Does the SN74ALS577ADW support 3.3 V operation?
No, the SN74ALS577ADW is specified only for 4.5 V to 5.5 V supply operation and is not rated for 3.3 V use. Its input thresholds (VIH = 2 V, VIL = 0.7 V) and output drive characteristics are optimized for 5 V TTL compatibility. Operating below 4.5 V may result in unreliable switching or increased propagation delay beyond specification.
What is the purpose of the NC pins on the SN74ALS577ADW?
Pins 22, 23, and 24 of the SN74ALS577ADW are designated NC (No internal connection) per the official TI datasheet SDAS065B. These pins have no internal bond wires or circuitry and must remain unconnected in PCB layout to prevent unintended coupling, noise injection, or mechanical stress on the package leads.
How does the synchronous clear (CLR) differ from asynchronous reset in the SN74ALS577ADW?
In the SN74ALS577ADW, CLR is synchronous: it only takes effect on the next rising edge of CLK, ensuring predictable, clock-aligned register clearing. This differs from asynchronous reset, which would immediately force outputs regardless of clock phase. The synchronous behavior prevents metastability and enables coordinated system-level initialization within a defined clock cycle.
Can the SN74ALS577ADW replace the SN74ALS576B in an existing design?
No - the SN74ALS577ADW cannot directly replace the SN74ALS576B. While both are octal D-type flip-flops in SOIC packages, SN74ALS576B uses asynchronous master reset (MR) on Pin 1 and lacks CLR, has different pinout (20-pin vs. 24-pin), and omits three NC pins. Substitution would require PCB layout changes and reset logic redesign.
SN74ALS577ADW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Function:
- Master Reset
- Type:
- D-Type
- Output Type:
- Tri-State, Inverted
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- 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):
- 18 mA
- Input Capacitance:
- -
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SOIC
SN74ALS577ADW FAQ
1.How can I place an order for SN74ALS577ADW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS577ADW 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 SN74ALS577ADW reliable?
The price and inventory of SN74ALS577ADW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS577ADW is usually 5 days.
3.What payment methods are accepted for SN74ALS577ADW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS577ADW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS577ADW?
SN74ALS577ADW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS577ADW 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 SN74ALS577ADW?
For technical support, including SN74ALS577ADW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS577ADW requirements.
6.How does Aetrix verify that SN74ALS577ADW is sourced from the original manufacturer or authorized distributors?
All SN74ALS577ADW 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 SN74ALS577ADW meets industry standards.
7.What is the process for return or replacement of SN74ALS577ADW?
All SN74ALS577ADW units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS577ADW, 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 SN74ALS577ADW part is unused and in its original packaging.
Return procedure for SN74ALS577ADW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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