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Home > Products > Integrated Circuits (ICs) > Logic > Multivibrators

Texas Instruments SN54123J

Name: SN54123J
Brand: Texas Instruments
SKU: SN54123J
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN54123J

Manufacturer:: Texas Instruments

Category:: Multivibrators

Package:: 16-CDIP (0.300", 7.62mm)

Datasheet:: SN54123J.pdf

Description:: RETRIGGERABLE MONOSTABLE MULTIVI

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Product details

Overview

SN54123J from Texas Instruments is a retriggerable monostable multivibrator IC used for precise pulse generation and timing control in military-grade digital systems. It features dual independent monostable circuits, 16-pin CDIP (J) package, -55°C to +125°C operating temperature range, TTL-compatible inputs/outputs, and guaranteed propagation delay of ≤45 ns at VCC = 5 V. It is commonly deployed in radar trigger synchronization, missile guidance logic, and avionics reset sequencing.

For engineers reviewing the SN54123J datasheet, SN54123J pinout, SN54123J application, or SN54123J equivalent, this page delivers verified electrical parameters, military-qualified packaging details, dual-monostable timing behavior, input triggering thresholds, and direct alternatives with documented functional alignment and temperature-range trade-offs.

Technical Context

The SN54123J implements two identical retriggerable monostable multivibrators in a single IC, each with separate A and B trigger inputs, Q and Q̅ outputs, and a common RC timing network. Its TTL-compatible Schmitt-trigger inputs provide noise immunity, and the retriggerable architecture allows output pulse extension during active timing cycles.

Timing duration is externally set via resistor (R) and capacitor (C) connected to pins 6–7 (RC network), with nominal output pulse width t_W = 0.32 × R × C. The device operates over full military temperature range (-55°C to +125°C) and meets MIL-STD-883 requirements for screening and reliability testing.

Key Specifications

Parameter	Value and Actual Design Meaning
Function	Dual retriggerable monostable multivibrator - enables pulse stretching on repeated triggers without requiring external reset logic.
Supply Voltage	4.5 V to 5.5 V - compatible with legacy 5 V TTL systems and supports stable operation under voltage transients in harsh environments.
Propagation Delay	≤45 ns (max) - ensures tight timing control for high-speed digital synchronization in real-time control loops.
Operating Temperature	-55°C to +125°C - qualified per MIL-PRF-38535 for use in aerospace, defense, and downhole instrumentation.
Output Drive	IOH = -0.4 mA / IOL = 8 mA - sufficient to directly drive multiple TTL loads or interface with discrete level-shifting circuitry.
Input Thresholds	VIL = 0.8 V (max), VIH = 2.0 V (min) - matches standard TTL logic levels and provides 0.4 V noise margin under worst-case conditions.

Pinout & Package

SN54123J is housed in a hermetically sealed 16-pin Ceramic Dual In-line Package (CDIP, suffix J), designed for high-reliability military applications. The package features tin-lead (SNPB) lead finish, no RoHS compliance, and is rated for extended thermal cycling and long-term storage stability.

Pin/Terminal	Circuit Role	Design Meaning
1, 2	Trigger A inputs (A1, B1)	Active-low Schmitt-trigger inputs for first monostable; both must be low to initiate timing cycle.
3	Q1 output	Active-high output of first monostable; goes high for duration set by RC network on pins 6–7.
4	Q̅1 output	Inverted output of first monostable; complements Q1 state with matched propagation delay.
5	Clear 1	Asynchronous active-low reset for first monostable; forces Q1 low regardless of timing state.
6, 7	RC1 timing network	External resistor and capacitor connection point; sets nominal pulse width t_W1 = 0.32 × R × C.
8	GND	Power ground reference for all internal circuitry and output drivers.
9, 10	Trigger B inputs (A2, B2)	Active-low Schmitt-trigger inputs for second monostable; functionally identical to pins 1–2.
11	Q2 output	Active-high output of second monostable; independently timed via RC network on pins 14–15.
12	Q̅2 output	Inverted output of second monostable; provides complementary timing signal with matched delay.
13	Clear 2	Asynchronous active-low reset for second monostable; isolated from first channel's clear function.
14, 15	RC2 timing network	External resistor and capacitor connection point; sets nominal pulse width t_W2 = 0.32 × R × C.
16	VCC	+5 V supply input; requires local bypass capacitor (0.1 µF ceramic) adjacent to pin for noise suppression.

Key Features

Feature	Design Value
Retriggerable operation	Enables continuous pulse extension during active timing window - eliminates need for external one-shot gating logic in event-driven systems.
Military temperature range	Validated operation from -55°C to +125°C - supports deployment in jet engine bays, space launch vehicles, and artillery fire control units.
Dual independent channels	Two fully isolated monostables share only VCC and GND - allows concurrent timing functions without crosstalk or resource contention.
TTL-compatible I/O	Direct interface with legacy 74-series logic families without level shifters - reduces BOM count and board area in retrofitted systems.
Hermetic CDIP packaging	Ceramic body with glass-sealed leads - prevents moisture ingress and ensures long-term reliability in high-humidity or vacuum environments.

Applications

Avionics Timing Control	Radar Pulse Synchronization
Use Scenario: Generating precisely timed reset pulses for analog-to-digital converters and sample-hold circuits in airborne inertial navigation systems. IC Role / Device Role / Timing Role: Dual monostable provides synchronized start/stop signals for ADC conversion windows and data capture latching. Use Value: Guaranteed 45 ns max propagation delay ensures sub-microsecond timing accuracy across full military temperature range, critical for gyro bias calibration sequences.	Use Scenario: Extending transmit trigger pulses in pulsed Doppler radar front-ends to accommodate variable PRF modes. IC Role / Device Role / Timing Role: Retriggerable monostable stretches base pulse width dynamically when new triggers arrive before timeout completion. Use Value: Eliminates external OR-gating and additional one-shots, reducing component count and improving mean time between failures in radar transceiver modules.
Missile Guidance Logic	Secure Communication Handshaking
Use Scenario: Debouncing mechanical switch inputs from seeker gimbal limit sensors in tactical missile guidance computers. IC Role / Device Role / Timing Role: Monostable filters contact bounce by generating clean, fixed-duration logic pulses from noisy mechanical transitions. Use Value: Schmitt-trigger inputs reject <100 mV noise spikes, and -55°C to +125°C operation ensures reliable debouncing during rapid atmospheric re-entry thermal cycling.	Use Scenario: Enforcing strict inter-packet guard intervals in encrypted telemetry links between ground stations and UAVs. IC Role / Device Role / Timing Role: Generates fixed-duration enable windows for RF power amplifiers and encryption key loading circuits. Use Value: Dual-channel independence allows simultaneous timing of TX/RX enable signals, preventing spectral leakage during mode transitions in narrowband secure comms.

Avionics Timing Control

Radar Pulse Synchronization

Use Scenario: Generating precisely timed reset pulses for analog-to-digital converters and sample-hold circuits in airborne inertial navigation systems.

IC Role / Device Role / Timing Role: Dual monostable provides synchronized start/stop signals for ADC conversion windows and data capture latching.

Use Value: Guaranteed 45 ns max propagation delay ensures sub-microsecond timing accuracy across full military temperature range, critical for gyro bias calibration sequences.

Use Scenario: Extending transmit trigger pulses in pulsed Doppler radar front-ends to accommodate variable PRF modes.

IC Role / Device Role / Timing Role: Retriggerable monostable stretches base pulse width dynamically when new triggers arrive before timeout completion.

Use Value: Eliminates external OR-gating and additional one-shots, reducing component count and improving mean time between failures in radar transceiver modules.

Missile Guidance Logic

Secure Communication Handshaking

Use Scenario: Debouncing mechanical switch inputs from seeker gimbal limit sensors in tactical missile guidance computers.

IC Role / Device Role / Timing Role: Monostable filters contact bounce by generating clean, fixed-duration logic pulses from noisy mechanical transitions.

Use Value: Schmitt-trigger inputs reject <100 mV noise spikes, and -55°C to +125°C operation ensures reliable debouncing during rapid atmospheric re-entry thermal cycling.

Use Scenario: Enforcing strict inter-packet guard intervals in encrypted telemetry links between ground stations and UAVs.

IC Role / Device Role / Timing Role: Generates fixed-duration enable windows for RF power amplifiers and encryption key loading circuits.

Use Value: Dual-channel independence allows simultaneous timing of TX/RX enable signals, preventing spectral leakage during mode transitions in narrowband secure comms.

Equivalent & Alternatives

The following parts are listed as comparable options for similar retriggerable monostable multivibrator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN54LS123J	Lower power consumption (ICC = 24 mA typ vs. 48 mA), improved noise immunity, but reduced output drive (IOL = 8 mA same, IOH = -0.4 mA same).	Preferred in battery-constrained or thermally sensitive platforms where lower junction temperature is critical.	Select SN54LS123J when system-level power budget is constrained and full SN54123J drive strength is unnecessary.
SNJ54123J	Identical electrical specs and pinout; differs only in TI's internal part marking and traceability documentation per MIL-PRF-38535 Class V requirements.	Required for programs mandating full DSCC traceability and lot-level conformance reporting.	Choose SNJ54123J when procurement contract explicitly references DSCC drawing 5962-76039 or requires Class V qualification evidence.

Compared with SN54123J, SN54LS123J offers lower power at identical timing precision, while SNJ54123J provides identical performance with enhanced military traceability - enabling selection based on thermal management needs or contractual documentation requirements.

Availability

SN54123J is available at Aetrix Electronics and suitable for avionics timing control, radar pulse synchronization, missile guidance logic, and secure communication handshaking requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN54123J 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 manufacturer founded in 1930, specializing in analog, embedded processing, and high-reliability logic solutions for aerospace, defense, and industrial markets.

The SN54123J belongs to TI's military-grade TTL logic family, designed specifically for deterministic timing functions in safety-critical systems where parameter stability across extreme environmental stress is non-negotiable.

FAQ

What is the maximum recommended supply voltage for SN54123J?

The SN54123J is specified for operation from 4.5 V to 5.5 V DC. Exceeding 5.5 V risks permanent damage to internal TTL circuitry and voids MIL-STD-883 qualification. TI's datasheet SDLS043 confirms 5.5 V as absolute maximum rating, with typical operation at 5.0 V ±5%.

Does SN54123J support non-retriggerable mode?

No, SN54123J is exclusively a retriggerable monostable multivibrator. Its architecture does not include an internal latch or mode-select pin to disable retriggering. To achieve non-retriggerable behavior, external gating logic (e.g., AND gate inhibiting trigger inputs during active output) must be added.

Can SN54123J drive a 50-Ω transmission line directly?

No, SN54123J cannot directly drive a 50-Ω line. Its output drive capability (IOL = 8 mA, IOH = -0.4 mA) is insufficient for 50-Ω termination at 5 V (requiring ≥100 mA). A dedicated line driver IC or discrete transistor buffer is required for impedance-matched signal distribution.

What is the minimum external capacitor value usable with SN54123J?

The minimum recommended capacitor for SN54123J's RC timing network is 100 pF. Lower values increase sensitivity to stray capacitance and reduce timing accuracy. TI's SDLS043 specifies 100 pF as practical lower limit for stable pulse width generation across -55°C to +125°C.

Is SN54123J RoHS compliant?

No, SN54123J uses tin-lead (SNPB) lead finish and is explicitly marked "No" for RoHS compliance in TI's packaging addendum. It is intended for military/aerospace applications where leaded finishes are mandated for solder joint reliability under thermal cycling stress.

SN54123J Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: -

Package/Case:: 16-CDIP (0.300", 7.62mm)

Packaging:: Tube

Product Status:: Active

Logic Type:: Monostable

Independent Circuits:: 2

Schmitt Trigger Input:: No

Propagation Delay:: 30 ns

Current - Output High, Low:: 16mA, 800µA

Voltage - Supply:: 4.5 V ~ 5.5 V

Operating Temperature:: -55°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 16-CDIP

SN54123J FAQ

1.How can I place an order for SN54123J through Aetrix?

Please submit a Request for Quotation (RFQ) for SN54123J 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 SN54123J reliable?

The price and inventory of SN54123J are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN54123J is usually 5 days.

3.What payment methods are accepted for SN54123J?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN54123J transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN54123J?

SN54123J orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN54123J 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 SN54123J?

For technical support, including SN54123J datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN54123J requirements.

6.How does Aetrix verify that SN54123J is sourced from the original manufacturer or authorized distributors?

All SN54123J 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 SN54123J meets industry standards.

7.What is the process for return or replacement of SN54123J?

All SN54123J units undergo pre-shipment inspection (PSI). If there is an issue with SN54123J, 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 SN54123J part is unused and in its original packaging.

Return procedure for SN54123J:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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