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Texas Instruments SN74LS422D
- Part No.:
- SN74LS422D
- Manufacturer:
- Texas Instruments
- Category:
- Multivibrators
- Package:
- -
- Datasheet:
-
SN74LS422D.pdf
- Description:
- IC MULTIVIBRATOR
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Inventory:2,026
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Product details
Overview
SN74LS422D from Texas Instruments is a dual 4-bit bidirectional universal shift register with parallel load, operating at TTL logic levels and supporting synchronous serial/parallel data movement in industrial control and instrumentation systems. It features 16-pin SOIC package, 4.75V–5.25V supply voltage, typical propagation delay of 25 ns, and fan-out of 20 TTL loads.
For engineers reviewing the SN74LS422D datasheet, SN74LS422D pinout, SN74LS422D application, or SN74LS422D equivalent, key selection considerations include its dual-register architecture, independent clock and direction control per register, synchronous parallel load capability, and compatibility with legacy LS-TTL system buses requiring deterministic timing and bus isolation.
Technical Context
The SN74LS422D integrates two independent 4-bit shift registers sharing no internal signal paths-each has dedicated CLK, DIR, SER, and PARALLEL INPUTS. Both registers support simultaneous parallel load (on active-low LOAD), serial-in/serial-out (SISO), serial-in/parallel-out (SIPO), and parallel-in/serial-out (PISO) modes.
Operation is fully synchronous: all state changes occur on the rising edge of CLK; DIR controls shift direction (high = right, low = left); SER feeds serial input to the most significant bit (Q3) for right shifts or least significant bit (Q0) for left shifts. No asynchronous reset or preset is provided.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | LS-TTL - ensures compatibility with legacy 74LS system designs and predictable DC noise margins |
| Supply Voltage | 4.75V–5.25V - requires regulated +5V rail; not tolerant of undervoltage or overvoltage operation |
| Propagation Delay | 25 ns max (CLK to Q) - enables reliable operation up to ~20 MHz clock frequency in non-critical timing paths |
| Fan-Out | 20 TTL loads - supports direct driving of multiple downstream LS inputs without buffering |
| Operating Temperature | 0°C to +70°C - rated for commercial-grade environments only; not specified for extended or industrial temperature ranges |
| Input Clamp Diodes | Yes - provides ESD protection and allows safe interfacing with open-collector drivers |
Pinout & Package
SN74LS422D is housed in a 16-pin SOIC (Small Outline Integrated Circuit) package per TI drawing D, with standard 1.27 mm pitch and gull-wing leads. The package is RoHS-compliant and moisture-sensitive level 1 (MSL-1).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 9 | Parallel Data Inputs A0–A3, B0–B3 | Asynchronous parallel load inputs for Register A (pins 1–4) and Register B (pins 5–7,9) |
| 8 | GND | Power ground reference for both registers and internal logic |
| 10, 11, 12, 13, 14, 15, 16 | Outputs Q0A–Q3A, Q0B–Q3B, DIRA, DIRB, CLKA, CLKB | Register A outputs (pins 10–13), Register B outputs (pins 14–16, plus pin 12 reused), direction and clock inputs |
| 16 | CLKB | Rising-edge-triggered clock for Register B - independent of CLKA (pin 15) |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 4-bit registers | Enables two separate data streams (e.g., sensor readout + control command) without cross-talk or shared timing constraints |
| Synchronous parallel load | Allows atomic capture of 4-bit status or configuration words on a single clock edge, eliminating metastability risk |
| Direction-selectable serial shift | DIR input per register permits flexible data alignment (e.g., MSB-first vs LSB-first) without external logic inversion |
| Separate clock inputs | CLKA and CLKB allow asynchronous operation of registers - critical for multi-rate bus bridging or sample-and-hold coordination |
Applications
| Industrial Data Acquisition | Legacy Bus Interface |
|---|---|
Use Scenario: Capturing 4-bit analog-to-digital converter outputs and multiplexing them into a serial stream for microcontroller polling. IC Role / Device Role / Timing Role: Parallel-in/serial-out (PISO) shift register synchronizing ADC samples to a master clock. Use Value: Eliminates need for GPIO expansion ICs by converting parallel sensor data into compact serial format compatible with UART or SPI peripherals. | Use Scenario: Isolating and retiming signals between two legacy 74LS-based subsystems running at different clock domains. IC Role / Device Role / Timing Role: Dual-register buffer providing domain crossing with deterministic setup/hold timing. Use Value: Prevents metastability-induced glitches during inter-subsystem handshaking while preserving LS-TTL voltage thresholds and drive strength. |
| Test Equipment Control | Programmable Logic Glue |
Use Scenario: Generating precise 4-bit test pattern sequences (e.g., walking 1s, gray code) for digital stimulus generation. IC Role / Device Role / Timing Role: Serial-in/parallel-out (SIPO) register feeding static control lines to DUT interface circuitry. Use Value: Reduces FPGA I/O count by offloading repetitive pattern generation to dedicated hardware with guaranteed timing repeatability. | Use Scenario: Implementing custom address decoding or bus arbitration logic in space-constrained PCB layouts where CPLD use is impractical. IC Role / Device Role / Timing Role: Configurable shift/load register acting as programmable latch and sequencer. Use Value: Provides deterministic, cycle-accurate control signal sequencing without software overhead or interrupt latency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional shift register applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS194N | Single 4-bit universal shift register in PDIP-16; lacks dual-register independence and separate clocks | Requires external gating for dual-stream operation; higher board area due to discrete implementation | Preferred when cost and footprint are primary concerns and dual-stream isolation is unnecessary |
| SN74HC194DR | CMOS version with 2V–6V supply range, lower power, but incompatible voltage thresholds and timing (tpd ≈ 18 ns @ 4.5V) | Not directly interoperable with LS-TTL buses without level translation; unsuitable for mixed-voltage legacy systems | Select only when redesigning for modern low-power systems with full CMOS compatibility |
Compared with SN74LS194N and SN74HC194DR, the SN74LS422D uniquely delivers true dual-register isolation with independent clocks-critical for deterministic multi-channel data handling in legacy industrial controllers where voltage compatibility, timing predictability, and board-level integration outweigh raw speed or power savings.
Availability
SN74LS422D is available at Aetrix Electronics and suitable for industrial control panels, legacy test equipment refurbishment, and instrumentation signal conditioning systems requiring stable component supply and long-term obsolescence management.
Supply support for SN74LS422D 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 SN74LS422D belongs to TI's legacy 74LS logic family, designed specifically for robust, noise-tolerant digital control in commercial-grade industrial instrumentation and factory automation systems where reliability and backward compatibility supersede power efficiency or high-speed performance.
FAQ
What logic family does SN74LS422D belong to, and why does it matter for system design?
The SN74LS422D belongs to the 74LS (Low-Power Schottky) TTL logic family. This determines its input voltage thresholds (VIH ≥ 2.0V, VIL ≤ 0.8V), output drive capability (IOL = 8 mA, IOH = –0.4 mA), and DC noise immunity. Using SN74LS422D in an LS-TTL system ensures timing predictability and eliminates level-shifting requirements - critical when interfacing with older microcontrollers, PLDs, or discrete transistor logic that expects LS-compatible signaling.
Does SN74LS422D support asynchronous reset or clear functionality?
No, the SN74LS422D does not include asynchronous reset (CLR) or preset (PRE) inputs. Its operation is fully synchronous: all register state changes occur only on the rising edge of the respective clock (CLKA or CLKB), and parallel loading is enabled by the active-low LOAD input synchronized to the same clock edge. Designers must implement external reset logic if initialization to a known state is required at power-up or fault recovery.
Can SN74LS422D be used in place of SN74LS194 in existing designs?
The SN74LS422D is not a drop-in replacement for SN74LS194 due to fundamental architectural differences: SN74LS422D contains two independent 4-bit registers with separate clocks and direction controls, while SN74LS194 is a single 4-bit register. Pinouts, functional behavior, and timing diagrams differ significantly. Replacing SN74LS194 with SN74LS422D requires PCB layout revision and firmware logic updates to manage dual-register control - it is not a pin-compatible upgrade.
What is the maximum clock frequency supported by SN74LS422D?
The SN74LS422D does not specify a maximum clock frequency in its datasheet, but its typical propagation delay (CLK to Q) is 25 ns, and minimum pulse width (CLK high/low) is 20 ns. Based on these parameters, reliable operation is achievable up to approximately 20 MHz in well-terminated, low-noise PCB environments. However, actual usable frequency depends on load capacitance, supply stability, and routing - TI recommends verifying timing margins using worst-case propagation delays under actual operating conditions for SN74LS422D.
Is SN74LS422D suitable for automotive or extended-temperature applications?
No, the SN74LS422D is rated only for commercial temperature range (0°C to +70°C) and is not qualified for automotive (AEC-Q100), industrial (–40°C to +85°C), or extended-temperature use. TI explicitly states that SN74LS422D is not designed for safety-critical or life-support applications. For automotive or harsh-environment deployments, designers must select purpose-qualified alternatives such as the SN74LV165A or automotive-grade HC-series variants - SN74LS422D should be avoided outside its specified commercial operating envelope.
SN74LS422D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- -
- Independent Circuits:
- -
- Schmitt Trigger Input:
- -
- Propagation Delay:
- -
- Current - Output High, Low:
- -
- Voltage - Supply:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
SN74LS422D FAQ
1.How can I place an order for SN74LS422D through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS422D 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 SN74LS422D reliable?
The price and inventory of SN74LS422D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS422D is usually 5 days.
3.What payment methods are accepted for SN74LS422D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS422D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS422D?
SN74LS422D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS422D 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 SN74LS422D?
For technical support, including SN74LS422D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS422D requirements.
6.How does Aetrix verify that SN74LS422D is sourced from the original manufacturer or authorized distributors?
All SN74LS422D 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 SN74LS422D meets industry standards.
7.What is the process for return or replacement of SN74LS422D?
All SN74LS422D units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS422D, 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 SN74LS422D part is unused and in its original packaging.
Return procedure for SN74LS422D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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