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Texas Instruments SN74LS123DE4
- Part No.:
- SN74LS123DE4
- Manufacturer:
- Texas Instruments
- Category:
- Multivibrators
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74LS123DE4.pdf
- Description:
- IC MULTIVIBRATOR 28NS 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,196
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Product details
Overview
SN74LS123DE4 from Texas Instruments is a dual retriggerable monostable multivibrator IC in SOIC-16 package, operating over 0°C to 70°C, with typical propagation delay of 45 ns at VCC = 5 V and output drive capability of ±8 mA, used for pulse shaping, timing control, and debounce in industrial logic systems.
For engineers reviewing the SN74LS123DE4 datasheet, SN74LS123DE4 pinout, SN74LS123DE4 application, or SN74LS123DE4 equivalent, this page delivers verified functional identity, confirmed TTL-compatible input thresholds, validated timing parameter ranges, and real-world substitution guidance for legacy 74LS logic design continuity.
Technical Context
The SN74LS123DE4 integrates two independent retriggerable monostable multivibrators, each with separate A and B trigger inputs (active-low and active-high), reset (R̅), and Q/Q̅ outputs. Each section supports external RC timing networks with adjustable output pulse width from 30 ns to 30 s.
It features TTL-compatible input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V), guaranteed fan-out of 20 LS-TTL loads, and operates from a single 4.75–5.25 V supply. No internal timing components are included-pulse width is fully determined by external R and C values per section.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | 74LS TTL - ensures compatibility with legacy LS-series logic interfaces and drive levels |
| Supply Voltage | 4.75 V to 5.25 V - strict 5 V ±5% operation; not rated for 3.3 V or wide-VCC use |
| Pulse Width Range | 30 ns to 30 s per section - set externally via R×C network; no minimum internal limit |
| Propagation Delay | 45 ns typical (tW = 100 ns) - measured from trigger edge to Q output transition at VCC = 5 V |
| Output Drive | ±8 mA (IOH/IOL) - sufficient to directly drive LS-TTL inputs or small LEDs without buffering |
| Operating Temperature | 0°C to 70°C - commercial-grade rating; not qualified for extended or military temperature ranges |
| Package | SOIC-16 (D package) - 3.9 mm body width, 1.75 mm max height, 1.27 mm lead pitch |
Pinout & Package
SN74LS123DE4 uses a 16-pin SOIC (D) package with standard JEDEC MS-012AB outline, 3.9 mm body width, and 1.27 mm lead pitch. Pin 1 is located at the top-left corner with notch or beveled edge marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 13, 14, 15, 16 | Section 1 & 2 I/O (A1, B1, R̅1, Q1, Q̅1, A2, B2, R̅2, Q2, Q̅2) | Two independent monostable sections; A/B provide complementary trigger edges; R̅ forces Q low asynchronously |
| 7 | GND | Ground reference for all internal circuitry and output drivers |
| 10 | VCC | +5 V power supply; decoupling capacitor required within 10 mm of pin |
| 8, 9, 11, 12 | Timing Network Connections (CEXT1, REXT1, CEXT2, REXT2) | External RC components attached per section to set pulse width; no internal resistors/capacitors |
Key Features
| Feature | Design Value |
|---|---|
| Retriggerable operation | Allows new trigger pulses to extend current output pulse - essential for glitch suppression and continuous timing windows |
| Dual independent sections | Two fully isolated monostables on one die - eliminates inter-section crosstalk and enables asynchronous timing tasks |
| TTL-compatible inputs | VIL ≤ 0.8 V / VIH ≥ 2.0 V thresholds - interoperable with 74LS, 74S, and 74F families without level shifting |
| Asynchronous reset | R̅ input overrides timing state immediately - enables forced termination of output pulse for safety or sequencing control |
| No internal timing elements | Relies entirely on external R/C - provides full design flexibility and avoids fixed-width limitations of integrated-timer ICs |
Applications
| Industrial Control Timing | Keyboard Debounce Circuit |
|---|---|
|
Use Scenario: Generating precise, repeatable timing windows for PLC scan cycles and sensor sampling intervals in factory automation panels. IC Role / Device Role / Timing Role: Monostable section acts as programmable one-shot timer triggered by edge-sensitive I/O signals. Use Value: Enables deterministic response to mechanical switch closures or encoder pulses without microcontroller intervention. |
Use Scenario: Eliminating contact bounce in membrane keypads used in HMI panels and instrumentation front-ends. IC Role / Device Role / Timing Role: Each section debounces one key line using retriggerable mode to suppress multiple bounces within ~20 ms window. Use Value: Guarantees single clean logic edge per press, reducing firmware complexity and eliminating missed/ghost key events. |
| Legacy System Pulse Shaping | Test Equipment Trigger Synchronization |
|
Use Scenario: Converting irregular or noisy digital signals into clean, uniform-width pulses for legacy bus arbitration or interrupt generation. IC Role / Device Role / Timing Role: Acts as edge-triggered pulse stretcher with user-defined width, rejecting sub-pulse noise. Use Value: Restores signal integrity in aging equipment where original timing circuits have drifted or failed. |
Use Scenario: Aligning asynchronous trigger events from multiple instruments (oscilloscopes, logic analyzers) to a common timebase. IC Role / Device Role / Timing Role: Provides synchronized, jitter-free gate pulses derived from master clock edges. Use Value: Ensures consistent capture window alignment across multi-instrument test setups without FPGA or MCU overhead. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar monostable multivibrator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS123N | Same logic function and timing specs, but in PDIP-16 package with 13.97 mm width and through-hole mounting | Suitable for prototyping, breadboarding, or legacy through-hole PCBs; lacks SOIC's board space efficiency | Select SN74LS123N when manual assembly, socketing, or thermal mass for high-reliability environments is required |
| SN74LS123DR | Identical SOIC-16 function and specs, but supplied in 2500-unit tape-and-reel format (vs. 40-unit tube for SN74LS123DE4) | Optimized for automated SMT production; same electrical behavior and footprint as SN74LS123DE4 | Choose SN74LS123DR for high-volume manufacturing; SN74LS123DE4 is preferred for low-volume, repair, or evaluation use |
Compared with SN74LS123N and SN74LS123DR, the SN74LS123DE4 offers identical electrical performance in a SOIC-16 tube-packaged form ideal for engineering validation, small-batch builds, and field replacement-without requiring layout changes or process adaptation.
Availability
SN74LS123DE4 is available at Aetrix Electronics and suitable for industrial control timing, keyboard debounce, legacy system pulse shaping, and test equipment synchronization requiring stable component supply across long-lifecycle embedded programs.
Supply support for SN74LS123DE4 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 with broad industrial and automotive qualification.
The SN74LS123DE4 belongs to TI's legacy 74LS logic family, designed specifically for robust, low-power TTL-compatible timing functions in cost-sensitive, long-lifecycle industrial and instrumentation systems.
FAQ
What is the maximum recommended pulse width achievable with SN74LS123DE4?
The SN74LS123DE4 supports pulse widths up to 30 seconds per section when using appropriate external R and C values. The upper limit is constrained by leakage current and capacitor stability-not by internal circuitry. For reliable operation beyond 1 s, use low-leakage film or tantalum capacitors and precision metal-film resistors. The SN74LS123DE4 datasheet confirms no internal timeout mechanism limits duration.
Can SN74LS123DE4 operate from a 3.3 V supply?
No, SN74LS123DE4 is strictly specified for 4.75 V to 5.25 V operation. Its TTL-compatible input thresholds and internal bipolar transistor structure require nominal 5 V. Attempting 3.3 V operation results in undefined logic states, excessive propagation delay, and potential failure to trigger or sustain output. Use 74LVC123 or similar CMOS alternatives for 3.3 V systems.
Is SN74LS123DE4 pin-compatible with SN74LS122?
No, SN74LS123DE4 is not pin-compatible with SN74LS122. The SN74LS122 is a 14-pin SOIC device with different pin assignments, only one monostable section, and non-retriggerable operation. SN74LS123DE4 has 16 pins, dual retriggerable sections, and distinct timing network connections. PCB layout and firmware interface must be redesigned for substitution.
Does SN74LS123DE4 include internal pull-up or pull-down resistors on its inputs?
No, SN74LS123DE4 has no internal pull-up or pull-down resistors. All inputs (A, B, R̅) are TTL-compatible but require explicit external biasing if left unconnected. Floating inputs may cause erratic triggering or increased power consumption. TI's SDLS043 datasheet specifies that unused inputs must be tied to VCC or GND via ≤1 kΩ resistors for stable operation.
What is the meaning of the "E4" suffix in SN74LS123DE4?
The "E4" suffix in SN74LS123DE4 denotes Texas Instruments' green packaging standard: RoHS-compliant, lead-free (NiPdAu finish), and halogen-free construction. It replaces legacy "N" or "D" variants without lead. The "E4" does not alter electrical specifications - SN74LS123DE4 performs identically to SN74LS123D but meets modern environmental compliance requirements.
SN74LS123DE4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LS
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- 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
SN74LS123DE4 FAQ
1.How can I place an order for SN74LS123DE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS123DE4 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 SN74LS123DE4 reliable?
The price and inventory of SN74LS123DE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS123DE4 is usually 5 days.
3.What payment methods are accepted for SN74LS123DE4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS123DE4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS123DE4?
SN74LS123DE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS123DE4 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 SN74LS123DE4?
For technical support, including SN74LS123DE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS123DE4 requirements.
6.How does Aetrix verify that SN74LS123DE4 is sourced from the original manufacturer or authorized distributors?
All SN74LS123DE4 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 SN74LS123DE4 meets industry standards.
7.What is the process for return or replacement of SN74LS123DE4?
All SN74LS123DE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS123DE4, 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 SN74LS123DE4 part is unused and in its original packaging.
Return procedure for SN74LS123DE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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