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Texas Instruments SN74LS423NG4
- Part No.:
- SN74LS423NG4
- Manufacturer:
- Texas Instruments
- Category:
- Multivibrators
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74LS423NG4.pdf
- Description:
- IC MULTIVIBRATOR 28NS 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,482
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Product details
Overview
SN74LS423NG4 from Texas Instruments is a dual monostable multivibrator IC in 16-pin PDIP package, featuring independent trigger inputs (A1/B1 and A2/B2), retriggerable operation, and typical propagation delay of 35 ns at VCC = 5 V. It operates across 0°C to 70°C and supports TTL-compatible input thresholds for use in digital timing, pulse shaping, and debounce circuits.
For engineers reviewing the SN74LS423NG4 datasheet, SN74LS423NG4 pinout, SN74LS423NG4 application, or SN74LS423NG4 equivalent, key selection considerations include retriggerability, independent reset control per section, output pulse width programmability via external RC networks, and compatibility with legacy LS-TTL logic families.
Technical Context
The SN74LS423NG4 integrates two independent retriggerable monostable multivibrators on a single die, each with separate A/B trigger inputs, clear (CLR) inputs, and Q/Q̅ outputs. Each section uses internal Schmitt-trigger inputs and TTL-level compatible thresholds.
Pulse width is externally set by resistor (R) and capacitor (C) connected between CEXT and REXT/CEXT pins, yielding tW ≈ 0.3 × R × C with R in kΩ and C in µF. Output pulse width ranges from 10 µs to 10 s depending on component values.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic family | LS-TTL - ensures interoperability with 74LS-series devices and defined noise margins at 5 V supply |
| Propagation delay | 35 ns typical - enables reliable timing in sub-10 MHz digital systems |
| Operating temperature | 0°C to +70°C - suitable for commercial-grade industrial control and instrumentation |
| Supply voltage | 4.75 V to 5.25 V - tight tolerance ensures stable timing accuracy under regulated 5 V rails |
| Pulse width range | 10 µs to 10 s - supports both short-duration event capture and long-interval timing via external RC |
| Output drive | IOH/ IOL = –0.4 mA / 8 mA - sufficient to directly drive multiple LS-TTL inputs or small LED loads |
Pinout & Package
SN74LS423NG4 is supplied in a 16-pin plastic dual in-line package (PDIP-N), with 0.3-inch body width and standard through-hole mounting footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 13, 14, 15, 16 | Input/Output terminals | Includes A1/B1/CLR1/Q1/Q̅1 and A2/B2/CLR2/Q2/Q̅2 - fully independent dual-section interface |
| 7 | GND | Ground reference for all internal circuitry and output stages |
| 14 | VCC | +5 V power supply connection - must be decoupled locally for stable timing |
| 9, 10, 11, 12 | RC timing nodes | CEXT1, REXT1/CEXT1, CEXT2, REXT2/CEXT2 - direct connection points for external timing components |
Key Features
| Feature | Design Value |
|---|---|
| Retriggerable operation | Allows pulse extension during active output - essential for detecting continuous or overlapping events |
| Independent clear control | Each monostable has dedicated CLR input - enables asynchronous reset without affecting the other section |
| External RC programmability | Timing precision determined by user-selected R and C - eliminates need for fixed-delay ICs |
| TTL-compatible inputs | Guaranteed recognition of 0.8 V low / 2.0 V high thresholds - ensures robust interfacing with legacy logic |
Applications
| Keyboard Debounce | Pulse Width Modulation Preconditioning |
|---|---|
Use Scenario: Mechanical keypresses generate contact bounce lasting 5–20 ms, causing false multiple interrupts. IC Role / Device Role / Timing Role: SN74LS423NG4 acts as dual-channel hardware debouncer, generating clean 20-ms pulses per keypress using RC-set timing. Use Value: Eliminates software polling overhead and ensures deterministic edge detection in microcontroller input capture units. | Use Scenario: Analog sensor signals require pulse-width encoding before transmission over digital links. IC Role / Device Role / Timing Role: SN74LS423NG4 converts analog threshold crossings into variable-width pulses, with width proportional to input amplitude. Use Value: Enables simple, low-cost PWM generation without ADC or microcontroller involvement. |
| Glitch Suppression in Control Logic | Event Timing Capture in Test Equipment |
Use Scenario: Asynchronous signal transitions in relay or switch interfaces introduce sub-microsecond spikes that corrupt state machines. IC Role / Device Role / Timing Role: SN74LS423NG4 filters transients by requiring minimum pulse width (e.g., 100 ns) for output assertion. Use Value: Prevents metastability in downstream flip-flops and eliminates need for multi-stage synchronizers. | Use Scenario: Bench test setups require precise measurement of time intervals between external triggers. IC Role / Device Role / Timing Role: SN74LS423NG4 generates gated enable windows synchronized to start/stop triggers for counter capture. Use Value: Provides hardware-based time-gating with <±5% accuracy, independent of host processor latency. |
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 pinout; requires separate RC per section but lacks retrigger capability | Suitable only where pulse extension on new trigger is not required | Select SN74LS221N when deterministic one-shot behavior is preferred and retriggering introduces risk of timing ambiguity |
| CD4098BE | CMOS dual retriggerable monostable; wider VDD range (3–15 V); higher input impedance; slower max speed (~2 MHz) | Better suited for battery-powered or mixed-voltage systems; incompatible with direct LS-TTL driving without level shift | Choose CD4098BE when operating outside 5 V or requiring ultra-low static current (<100 nA) |
Compared with SN74LS423NG4, SN74LS221N offers simpler timing predictability but no retriggering, while CD4098BE provides voltage flexibility and lower power at the cost of speed and TTL-level compatibility - selection depends on whether retriggerability, supply constraints, or interface compatibility dominate the design requirement.
Availability
SN74LS423NG4 is available at Aetrix Electronics and suitable for industrial control panels, legacy system repairs, and educational electronics labs requiring stable component supply and long-term obsolescence support.
Supply support for SN74LS423NG4 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 headquartered in Dallas, Texas, specializing in analog, embedded processing, and logic solutions since 1930.
The SN74LS423NG4 belongs to TI's legacy 74LS logic family, designed specifically for robust, low-power, medium-speed digital timing functions in commercial-grade systems.
FAQ
What is the maximum recommended supply voltage for SN74LS423NG4?
The absolute maximum supply voltage for SN74LS423NG4 is 5.5 V, but the device is specified for reliable operation only within 4.75 V to 5.25 V. Operating outside this range risks timing inaccuracy, increased power dissipation, and potential latch-up. Always use a well-regulated 5 V source with local 0.1 µF ceramic decoupling at the VCC pin adjacent to pin 14 to maintain SN74LS423NG4 performance stability.
Can SN74LS423NG4 operate with a single RC network shared between both sections?
No - SN74LS423NG4 requires separate RC timing networks for each monostable section. Pins 9/10 configure the first section's timing, and pins 11/12 configure the second. Sharing components would cause cross-coupling and unpredictable pulse widths. Each section's CEXT and REXT/CEXT nodes must be independently wired to ensure SN74LS423NG4 maintains functional isolation between channels.
Is SN74LS423NG4 RoHS compliant?
Yes, SN74LS423NG4 is RoHS compliant, as confirmed by Texas Instruments' official packaging documentation. The device uses NiPdAu (NIPDAU) lead finish and meets EU Directive 2011/65/EU requirements. No lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE substances exceed allowable thresholds. Full compliance data is available in TI's RoHS statement referenced under orderable part number SN74LS423NG4.
Does SN74LS423NG4 support negative-going trigger inputs?
Yes - SN74LS423NG4 accepts both positive- and negative-going triggers. Each section has two independent Schmitt-trigger inputs (A and B): A is active-high, B is active-low. This allows flexible edge detection without external inverters. For example, connecting a switch to B input provides native negative-edge triggering, making SN74LS423NG4 ideal for interrupt conditioning in legacy microprocessor systems.
What is the minimum pulse width achievable with SN74LS423NG4?
The minimum practical pulse width for SN74LS423NG4 is approximately 10 µs, achieved using R = 2 kΩ and C = 500 pF. Below this, parasitic capacitance and internal propagation delays dominate, reducing timing accuracy. TI's datasheet specifies 10 µs as the lower limit for guaranteed monotonic behavior. For shorter intervals, consider faster logic families like 74F or 74ACT - SN74LS423NG4 is optimized for µs-to-s scale timing, not nanosecond precision.
SN74LS423NG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LS
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- 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:
- Through Hole
- Supplier Device Package:
- 16-PDIP
SN74LS423NG4 FAQ
1.How can I place an order for SN74LS423NG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS423NG4 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 SN74LS423NG4 reliable?
The price and inventory of SN74LS423NG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS423NG4 is usually 5 days.
3.What payment methods are accepted for SN74LS423NG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS423NG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS423NG4?
SN74LS423NG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS423NG4 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 SN74LS423NG4?
For technical support, including SN74LS423NG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS423NG4 requirements.
6.How does Aetrix verify that SN74LS423NG4 is sourced from the original manufacturer or authorized distributors?
All SN74LS423NG4 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 SN74LS423NG4 meets industry standards.
7.What is the process for return or replacement of SN74LS423NG4?
All SN74LS423NG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS423NG4, 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 SN74LS423NG4 part is unused and in its original packaging.
Return procedure for SN74LS423NG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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