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

Texas Instruments SNJ54AHC123AFK

Name: SNJ54AHC123AFK
Brand: Texas Instruments
SKU: SNJ54AHC123AFK
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SNJ54AHC123AFK

Manufacturer:: Texas Instruments

Category:: Multivibrators

Package:: 20-CLCC

Datasheet:: SNJ54AHC123AFK.pdf

Description:: DUAL RETRIGGERABLE MONOSTABLE MU

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Product details

Overview

SNJ54AHC123AFK from Texas Instruments is a dual retriggerable monostable multivibrator in 20-pin LCCC (FK) package, operating from 2 V to 5.5 V, featuring Schmitt-trigger inputs for jitter-free triggering on slow transitions, edge-triggered gated logic inputs (active-high or active-low), and overriding clear functionality. It delivers programmable output pulse durations via external R/C networks and supports industrial temperature range (−55°C to +125°C).

For engineers reviewing the SNJ54AHC123AFK datasheet, SNJ54AHC123AFK pinout, SNJ54AHC123AFK application, or SNJ54AHC123AFK equivalent, key selection criteria include retriggerable pulse timing stability across voltage/temperature, dual-channel independent operation, glitch-free power-up reset, latch-up immunity (>100 mA), and compatibility with legacy military-grade logic systems requiring MIL-PRF-38535 compliance.

Technical Context

The SNJ54AHC123AFK implements two independent edge-triggered monostable circuits, each with three distinct trigger modes: A low + B high, B high + A low, or A low + B high + CLR high. Pulse duration is externally set by R_ext and C_ext, with K-factor scaling dependent on C_ext value (K = 1.0 if ≥1000 pF).

Each channel features Schmitt-trigger inputs on A, B, and CLR pins-ensuring noise immunity and consistent triggering despite slow input edges-and supports retriggering during active output to extend pulse width. The CLR input overrides all triggers and can terminate an output pulse early, while power-up guarantees Q = low and Q̅ = high with no external reset required.

Key Specifications

Parameter	Value and Actual Design Meaning
VCC Range	2 V to 5.5 V - Enables interoperability with 2.5 V, 3.3 V, and 5 V logic families without level shifting.
Operating Temperature	−55°C to +125°C - Qualified for military and aerospace applications per MIL-PRF-38535.
Output Drive	±8 mA at 5 V - Sufficient to drive standard TTL loads or multiple CMOS inputs directly.
Pulse Duration Range	~180 ns to >1 ms - Programmable via R_ext/C_ext; e.g., 10 kΩ + 0.1 μF yields ~1 ms nominal.
Input Hysteresis	Typical ΔV_IN = 0.5 V - Schmitt-trigger inputs reject noise and prevent false triggering on slow-rising/falling signals.
Latch-up Immunity	>100 mA per JESD78 Class II - Robust against transient current injection in harsh EMI environments.
Power-Up Behavior	Glitch-free Q = low, Q̅ = high - Eliminates need for external POR circuitry in system initialization.

Pinout & Package

SNJ54AHC123AFK uses a 20-pin Ceramic Leadless Chip Carrier (LCCC, FK package), hermetically sealed, with leads arranged in a square perimeter and no exposed leads-suitable for high-reliability, high-temperature, and vacuum environments.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3, 4, 5, 6, 7, 8, 9, 10	Channel 1 & 2 Inputs (A, B, CLR)	Dual independent trigger control: A/B define edge polarity; CLR provides asynchronous pulse termination.
11, 12, 13, 14, 15, 16	Outputs & Timing Nodes (Q, Q̅, Cext, Rext/Cext)	Complementary outputs per channel; dedicated pins for external timing capacitor negative terminal and R/C junction.
17, 18, 19, 20	Power & Ground (VCC, GND)	Four-terminal power distribution: dual VCC and dual GND pins minimize ground bounce and improve noise margin.

Key Features

Feature	Design Value
Retriggerable Output	Enables precise extension of output pulses mid-cycle using same A/B inputs-critical for variable-width timing windows in radar or motor control.
Overriding Clear	Active-high CLR forces immediate output termination regardless of ongoing retriggering-essential for safety-critical abort functions.
Schmitt-Trigger Inputs	Input hysteresis ≥0.5 V ensures reliable triggering on noisy or slow-slew signals (e.g., mechanical switch debouncing or sensor outputs).
Glitch-Free Power-Up	Guaranteed Q = low / Q̅ = high at power-on eliminates spurious pulses during system boot-reduces need for external reset sequencing.
MIL-PRF-38535 Compliance	Qualified to Class B screening with full traceability, lot acceptance testing, and extended temperature validation-required for defense/aerospace deployments.

Applications

Radar Pulse Width Modulation	Industrial Motor Control Sequencing
Use Scenario: Generating precisely timed, retriggerable gate pulses for magnetron or solid-state RF amplifiers in pulsed radar transmitters. IC Role / Device Role / Timing Role: Dual-channel monostable providing independent, jitter-immune pulse width control for transmit/receive timing and blanking intervals. Use Value: Schmitt-trigger inputs tolerate noisy trigger sources from timing generators; retriggering enables adaptive pulse stretching under dynamic load conditions.	Use Scenario: Controlling sequence timing in multi-axis servo drives, where motor enable, direction, and brake signals require synchronized, variable-duration activation. IC Role / Device Role / Timing Role: Dual monostable generating isolated, programmable delay windows for interlocked actuator commands and fault response windows. Use Value: Overriding CLR allows immediate shutdown of motion sequences upon emergency stop signal-meeting SIL-2 functional safety requirements.
Aerospace Avionics Watchdog Timing	Military Data Link Signal Conditioning
Use Scenario: Implementing hardware-based watchdog timeout windows in flight control computers, where processor reset must occur within strict latency bounds. IC Role / Device Role / Timing Role: Retriggerable monostable acting as self-resetting timer-cleared by periodic software strobes and asserting reset if missed. Use Value: −55°C to +125°C operation and MIL-qualified packaging ensure reliability across extreme thermal cycling in airborne platforms.	Use Scenario: Debouncing and pulse-shaping analog/digital interface signals in secure tactical radios, where EMI resilience and deterministic timing are critical. IC Role / Device Role / Timing Role: Input conditioning block converting noisy RF detector outputs or PTT signals into clean, fixed-duration logic pulses. Use Value: Input hysteresis and latch-up immunity prevent upset from radiated emissions; dual channels support redundant signal paths.

Radar Pulse Width Modulation

Industrial Motor Control Sequencing

Use Scenario: Generating precisely timed, retriggerable gate pulses for magnetron or solid-state RF amplifiers in pulsed radar transmitters.

IC Role / Device Role / Timing Role: Dual-channel monostable providing independent, jitter-immune pulse width control for transmit/receive timing and blanking intervals.

Use Value: Schmitt-trigger inputs tolerate noisy trigger sources from timing generators; retriggering enables adaptive pulse stretching under dynamic load conditions.

Use Scenario: Controlling sequence timing in multi-axis servo drives, where motor enable, direction, and brake signals require synchronized, variable-duration activation.

IC Role / Device Role / Timing Role: Dual monostable generating isolated, programmable delay windows for interlocked actuator commands and fault response windows.

Use Value: Overriding CLR allows immediate shutdown of motion sequences upon emergency stop signal-meeting SIL-2 functional safety requirements.

Aerospace Avionics Watchdog Timing

Military Data Link Signal Conditioning

Use Scenario: Implementing hardware-based watchdog timeout windows in flight control computers, where processor reset must occur within strict latency bounds.

IC Role / Device Role / Timing Role: Retriggerable monostable acting as self-resetting timer-cleared by periodic software strobes and asserting reset if missed.

Use Value: −55°C to +125°C operation and MIL-qualified packaging ensure reliability across extreme thermal cycling in airborne platforms.

Use Scenario: Debouncing and pulse-shaping analog/digital interface signals in secure tactical radios, where EMI resilience and deterministic timing are critical.

IC Role / Device Role / Timing Role: Input conditioning block converting noisy RF detector outputs or PTT signals into clean, fixed-duration logic pulses.

Use Value: Input hysteresis and latch-up immunity prevent upset from radiated emissions; dual channels support redundant signal paths.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74AHC123ADBR	Commercial-grade (−40°C to +85°C), SSOP-16, Pb-free, lower cost; lacks MIL qualification and extended temperature range.	Not suitable for aerospace/military use; acceptable for industrial automation or test equipment with benign thermal profiles.	Select when cost, RoHS compliance, and volume production outweigh military environmental requirements.
CD74HC123M	Standard HC family (not AHC); slower propagation (t_PLH/t_PHL ≈ 2× higher at 5 V), no Schmitt inputs on CLR, non-MIL qualified.	Lower speed and reduced noise immunity limit use in high-frequency or EMI-heavy environments like avionics or radar.	Choose only for legacy HC-system compatibility where timing margins are generous and temperature range is limited.

Compared with SNJ54AHC123AFK, SN74AHC123ADBR offers commercial cost and packaging advantages but sacrifices military temperature range and qualification; CD74HC123M provides pin-compatible HC logic but lacks Schmitt-triggered CLR and fails to meet AHC speed/noise performance-making SNJ54AHC123AFK irreplaceable in high-reliability, high-speed timing-critical systems.

Availability

SNJ54AHC123AFK is available at Aetrix Electronics and suitable for radar pulse generation, avionics watchdog timers, and military data link signal conditioning requiring stable component supply across extended temperature and long lifecycle commitments.

Supply support for SNJ54AHC123AFK 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 specializing in analog, embedded processing, and high-reliability logic solutions, with decades of heritage in military-grade component development.

The SNJ54AHC123AFK belongs to TI's 54AHC logic family-designed specifically for high-speed, low-power, radiation-tolerant applications in defense, aerospace, and industrial control systems demanding MIL-PRF-38535 compliance.

FAQ

What is the operating temperature range of the SNJ54AHC123AFK?

The SNJ54AHC123AFK is rated for −55°C to +125°C operation and is fully qualified per MIL-PRF-38535 Class B, making it suitable for extreme-environment applications including aerospace, defense, and downhole instrumentation where thermal cycling and reliability are mission-critical. This range exceeds commercial AHC variants like SN74AHC123A.

How does the retriggering function work in the SNJ54AHC123AFK?

In the SNJ54AHC123AFK, retriggering extends the output pulse duration while the monostable is active: applying a valid A or B edge trigger during an ongoing output pulse resets the internal timing cycle. Minimum retrigger interval is ~0.3 × t_w, enabling precise adaptive pulse-width control in real-time systems such as motor commutation or radar gating.

Can the SNJ54AHC123AFK be used with 3.3 V logic systems?

Yes, the SNJ54AHC123AFK operates over 2 V to 5.5 V, including 3.3 V nominal supply. At V_CC = 3.3 V, it delivers ±4 mA output drive, supports 5 ns minimum input pulse width, and maintains full Schmitt-trigger hysteresis-ensuring robust interfacing with FPGA I/O banks, microcontroller GPIOs, and other 3.3 V logic without level translation.

What external components are required for timing in the SNJ54AHC123AFK?

The SNJ54AHC123AFK requires one external resistor (R_ext) connected between V_CC and the Rext/Cext pin, and one external capacitor (C_ext) connected between Cext and Rext/Cext pins per channel. Pulse width follows t_w ≈ K × R_ext × C_ext, where K = 1.0 for C_ext ≥ 1000 pF. No additional biasing or feedback is needed.

Is the SNJ54AHC123AFK pin-compatible with other AHC123A variants?

No-SNJ54AHC123AFK uses a 20-pin LCCC (FK) package, whereas most other AHC123A variants (e.g., SN74AHC123AD, SN74AHC123ADBR) use 16-pin packages (SOIC, SSOP, TSSOP). Pin count, layout, and thermal/mechanical characteristics differ fundamentally; PCB redesign is required for substitution.

SNJ54AHC123AFK Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 54AHC

Package/Case:: 20-CLCC

Packaging:: Tube

Product Status:: Active

Logic Type:: Monostable

Independent Circuits:: 2

Schmitt Trigger Input:: Yes

Propagation Delay:: 8.7 ns

Current - Output High, Low:: 8mA, 8mA

Voltage - Supply:: 2 V ~ 5.5 V

Operating Temperature:: -55°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-LCCC (8.89x8.89)

SNJ54AHC123AFK FAQ

1.How can I place an order for SNJ54AHC123AFK through Aetrix?

Please submit a Request for Quotation (RFQ) for SNJ54AHC123AFK 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 SNJ54AHC123AFK reliable?

The price and inventory of SNJ54AHC123AFK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SNJ54AHC123AFK is usually 5 days.

3.What payment methods are accepted for SNJ54AHC123AFK?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SNJ54AHC123AFK transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SNJ54AHC123AFK?

SNJ54AHC123AFK orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SNJ54AHC123AFK 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 SNJ54AHC123AFK?

For technical support, including SNJ54AHC123AFK datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SNJ54AHC123AFK requirements.

6.How does Aetrix verify that SNJ54AHC123AFK is sourced from the original manufacturer or authorized distributors?

All SNJ54AHC123AFK 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 SNJ54AHC123AFK meets industry standards.

7.What is the process for return or replacement of SNJ54AHC123AFK?

All SNJ54AHC123AFK units undergo pre-shipment inspection (PSI). If there is an issue with SNJ54AHC123AFK, 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 SNJ54AHC123AFK part is unused and in its original packaging.

Return procedure for SNJ54AHC123AFK:

1.Submit a request within 90 days.

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

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