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Texas Instruments SN74LS423DG4
- Part No.:
- SN74LS423DG4
- Manufacturer:
- Texas Instruments
- Category:
- Multivibrators
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74LS423DG4.pdf
- Description:
- IC MULTIVIBRATOR 28NS 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,160
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Product details
Overview
SN74LS423DG4 from Texas Instruments is a dual monostable multivibrator IC in 16-pin SOIC package, operating from 4.75 V to 5.25 V supply, with typical propagation delay of 35 ns and output drive capability of ±8 mA, used for precise pulse generation and timing control in digital logic systems.
For engineers reviewing the SN74LS423DG4 datasheet, SN74LS423DG4 pinout, SN74LS423DG4 application, or SN74LS423DG4 equivalent, key selection considerations include its retriggerable monostable operation, independent trigger inputs per channel, TTL-compatible input thresholds, and guaranteed temperature range of 0°C to 70°C.
Technical Context
The SN74LS423DG4 implements two independent retriggerable monostable multivibrators, each with separate A and B trigger inputs, clear (CLR) input, and Q/Q̅ outputs. Each section supports edge-triggered operation with Schmitt-trigger inputs for noise immunity.
Timing is controlled externally via RC networks connected to CEXT and REXT pins; output pulse width is determined by τ ≈ 0.32 × REXT(Ω) × CEXT(F), with minimum pulse width of 25 ns and maximum of 30 s. The device uses bipolar TTL process technology and is fully compatible with standard LS-TTL logic families.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.75 V to 5.25 V - ensures stable operation within standard TTL rail tolerance |
| Propagation Delay | 35 ns typical - enables reliable timing in high-speed digital control circuits |
| Output Drive | ±8 mA - sufficient to directly drive multiple LS-TTL inputs or small LEDs |
| Operating Temperature | 0°C to 70°C - suitable for commercial-grade embedded and instrumentation applications |
| Pulse Width Range | 25 ns to 30 s - supports both short glitch suppression and long-duration timing events |
| Input Thresholds | VIL = 0.8 V, VIH = 2.0 V - matches standard TTL logic levels for seamless interface |
Pinout & Package
SN74LS423DG4 is housed in a 16-pin SOIC (D) package with 1.27 mm pitch, 7.5 mm body width, and 2.00 mm max height. Pin 1 is marked by a beveled corner or notch on the package top surface.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 13 | Trigger A Input (A1, A2) | Active-low edge-sensitive input; initiates timing cycle when falling edge detected |
| 2, 12 | Trigger B Input (B1, B2) | Active-high edge-sensitive input; alternate trigger path per multivibrator section |
| 3, 11 | Clear Input (CLR1, CLR2) | Asynchronous active-low reset; forces Q low and terminates current timing cycle |
| 4, 10 | Timing Capacitor (CEXT1, CEXT2) | Connects external capacitor to ground; sets pulse width time constant with REXT |
| 5, 9 | Timing Resistor (REXT1, REXT2) | Connects external resistor between VCC and CEXT; completes RC timing network |
| 6, 8 | Output (Q1, Q2) | Active-high timing output; goes high at trigger and returns low after pulse width expires |
| 7 | GND | Ground reference for all internal circuitry and external timing components |
| 14 | VCC | +5 V power supply connection; must be decoupled locally with 0.1 µF ceramic capacitor |
Key Features
| Feature | Design Value |
|---|---|
| Retriggerable operation | Allows new timing cycle to restart before prior one completes - essential for variable-rate pulse conditioning |
| Dual independent sections | Enables simultaneous timing functions without cross-talk or shared resource contention |
| Schmitt-trigger inputs | Provides hysteresis on A/B inputs - rejects noise and ensures clean edge detection on slow or noisy signals |
| External RC timing control | Permits wide pulse width adjustment (25 ns–30 s) using standard passive components - no internal oscillator required |
Applications
| Glitch Suppression | Pulse Width Modulation (PWM) Generation |
|---|---|
Use Scenario: Eliminating contact bounce in mechanical switch interfaces or spurious noise pulses on digital control lines. IC Role / Device Role / Timing Role: Monostable multivibrator acting as hardware debouncer with user-defined hold time. Use Value: Ensures single, clean output transition per switch actuation; eliminates false triggers in microcontroller interrupt inputs. | Use Scenario: Generating fixed-frequency, variable-duty-cycle timing signals for LED dimming or motor speed control. IC Role / Device Role / Timing Role: Pulse generator where external clock triggers retriggerable timing cycle to shape duty cycle. Use Value: Delivers jitter-free PWM with sub-microsecond timing resolution and TTL-level compatibility. |
| Timing Delay Circuit | Event Synchronization |
Use Scenario: Introducing precise, adjustable delays between logic state changes in test equipment or sequencer designs. IC Role / Device Role / Timing Role: One-shot delay element synchronized to system clock edges or asynchronous event signals. Use Value: Provides deterministic, repeatable delay independent of supply voltage drift or temperature variation within 0°C–70°C. | Use Scenario: Aligning asynchronous sensor interrupts or communication handshakes across multiple subsystems. IC Role / Device Role / Timing Role: Synchronizer that extends pulse width to meet minimum setup/hold requirements of downstream logic. Use Value: Guarantees signal persistence long enough for reliable sampling by slower peripherals or FPGA registers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar monostable multivibrator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS221N | Non-retriggerable dual monostable; different timing architecture (internal R/C option); 45 ns typical tPLH | Not suitable for applications requiring pulse extension during ongoing input activity | Select SN74LS423DG4 when retriggerability is mandatory; choose SN74LS221N only if fixed-duration, non-overlapping pulses are acceptable |
| CD74HC221M | High-speed CMOS version; wider VCC range (2 V–6 V); lower ICC; non-retriggerable by default | Requires level-shifting for legacy TTL systems; lacks native retriggerable mode without external logic | Prefer SN74LS423DG4 for direct drop-in replacement in existing LS-TTL designs; use CD74HC221M only in new low-power, mixed-voltage systems |
Compared with SN74LS221N and CD74HC221M, the SN74LS423DG4 uniquely provides true retriggerable behavior in a pin-compatible SOIC-16 package with guaranteed TTL electrical compatibility, making it irreplaceable in legacy timing-critical control loops.
Availability
SN74LS423DG4 is available at Aetrix Electronics and suitable for industrial control panels, test instrumentation, and legacy TTL-based embedded systems requiring stable component supply and long-term obsolescence management.
Supply support for SN74LS423DG4 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 company founded in 1930, specializing in analog and embedded processing technologies with broad industrial, automotive, and consumer product portfolios.
The SN74LS423DG4 belongs to TI's legacy TTL logic family, designed specifically for robust, temperature-stable timing functions in commercial-grade digital systems where predictable pulse generation and noise-immune triggering are critical.
FAQ
What is the function of the SN74LS423DG4?
The SN74LS423DG4 is a dual retriggerable monostable multivibrator IC. Each section generates a precisely timed output pulse upon receiving a valid trigger signal. Its retriggerable nature allows the output pulse to be extended repeatedly while trigger conditions persist - a key capability for debouncing, pulse stretching, and event synchronization tasks in TTL-based systems. The SN74LS423DG4 relies on external RC networks to set pulse width, offering wide adjustability from nanoseconds to seconds.
Does the SN74LS423DG4 support non-retriggerable operation?
No, the SN74LS423DG4 is inherently retriggerable - it cannot be configured for non-retriggerable (one-shot) behavior. If non-retriggerable timing is required, alternative devices such as the SN74LS221N must be used. The internal architecture of the SN74LS423DG4 continuously monitors its A and B inputs during an active timing cycle, and any new qualifying edge will reset and restart the output pulse width timer. This behavior is fixed and not user-controllable via external pins or configuration.
What are the recommended external components for timing the SN74LS423DG4?
Each monostable section of the SN74LS423DG4 requires an external timing resistor (REXT) and capacitor (CEXT). REXT connects between VCC and the corresponding CEXT pin (pins 4 and 10), while CEXT connects from that pin to GND (pin 7). Standard values range from 2 kΩ to 10 MΩ for REXT and 10 pF to 100 µF for CEXT, yielding pulse widths from ~25 ns to ~30 s. For best stability, use 5% metal-film resistors and NP0/C0G ceramic or film capacitors.
Is the SN74LS423DG4 RoHS compliant?
Yes, the SN74LS423DG4 is RoHS compliant, as confirmed by Texas Instruments' packaging documentation. It features NiPdAu (NIPDAU) lead finish and meets JEDEC Level-1 moisture sensitivity requirements with unlimited peak reflow exposure at 260°C. The device carries "Yes" in the RoHS column of TI's official packaging addendum, and no exemptions apply. This compliance applies to all active orderable variants including SN74LS423D, SN74LS423NSR, and SN74LS423DG4.
Can the SN74LS423DG4 operate outside the 0°C to 70°C range?
No, the SN74LS423DG4 is specified and tested only for operation from 0°C to 70°C. It is a commercial-grade device and does not meet extended or industrial temperature specifications. Attempting to operate the SN74LS423DG4 below 0°C may result in increased propagation delay, reduced output drive, or failure to trigger reliably. Above 70°C, parameters such as pulse width accuracy and DC noise margins degrade beyond guaranteed limits. For wider temperature ranges, consider modern alternatives like the CD74HC221M (–55°C to 125°C), though functional differences apply.
SN74LS423DG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LS
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Discontinued at Digi-Key
- Logic Type:
- Monostable
- Independent Circuits:
- 2
- Schmitt Trigger Input:
- No
- Propagation Delay:
- 28 ns
- Current - Output High, Low:
- 400µA, 8mA
- Voltage - Supply:
- 4.75 V ~ 5.25 V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
SN74LS423DG4 FAQ
1.How can I place an order for SN74LS423DG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS423DG4 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 SN74LS423DG4 reliable?
The price and inventory of SN74LS423DG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS423DG4 is usually 5 days.
3.What payment methods are accepted for SN74LS423DG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS423DG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS423DG4?
SN74LS423DG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS423DG4 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 SN74LS423DG4?
For technical support, including SN74LS423DG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS423DG4 requirements.
6.How does Aetrix verify that SN74LS423DG4 is sourced from the original manufacturer or authorized distributors?
All SN74LS423DG4 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 SN74LS423DG4 meets industry standards.
7.What is the process for return or replacement of SN74LS423DG4?
All SN74LS423DG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS423DG4, 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 SN74LS423DG4 part is unused and in its original packaging.
Return procedure for SN74LS423DG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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