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

Texas Instruments CD74HC123MG4

Name: CD74HC123MG4
Brand: Texas Instruments
SKU: CD74HC123MG4
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: CD74HC123MG4

Manufacturer:: Texas Instruments

Category:: Multivibrators

Package:: 16-SOIC (0.154", 3.90mm Width)

Datasheet:: CD74HC123MG4.pdf

Description:: IC MULTIVIBRATOR 25NS 16SOIC

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Product details

Overview

CD74HC123MG4 from Texas Instruments is a dual retriggerable monostable multivibrator with independent resets, operating from 2V to 6V. It features Schmitt-trigger inputs on both A and B trigger pins, buffered Q and Q̅ outputs, and external RC timing (t_W = 0.45·R_XC_X at V_CC = 5V). Used in pulse shaping, debouncing, and delay generation within industrial control logic and test equipment.

For engineers reviewing the CD74HC123MG4 datasheet, CD74HC123MG4 pinout, CD74HC123MG4 application, or CD74HC123MG4 equivalent, key selection criteria include retriggerable operation, edge-selective triggering (A = trailing, B = leading), overriding reset capability, wide temperature range (–55°C to +125°C), and SOIC-16 package compatibility with standard PCB assembly processes.

Technical Context

The CD74HC123MG4 implements two independent monostable circuits, each with separate A (trailing-edge), B (leading-edge), and R (active-low reset) inputs. Triggering is enabled by Schmitt-trigger input thresholds (VIH = 3.15V, VIL = 1.35V at VCC = 4.5V), ensuring noise immunity and consistent edge detection regardless of input slew rate.

Each monostable supports retriggering during output pulse width, extending t_W dynamically. Pulse termination is achieved via low-level assertion on R, independent of ongoing timing. Minimum external R_X = 5 kΩ and C_X = 0 pF enable pulse widths from ~100 ns to >100 ms depending on RC values.

Key Specifications

Parameter	Value and Actual Design Meaning
Supply Voltage	2V to 6V - Enables direct interface with 3.3V and 5V logic systems without level shifting.
Operating Temperature	–55°C to +125°C - Qualified for extended industrial and automotive under-hood applications.
Output Pulse Width	t_W = 0.45·R_XC_X (at V_CC = 5V) - Predictable, externally adjustable timing with ±2% match between internal monostables.
Propagation Delay	64 ns max (A/B/R to Q, V_CC = 4.5V, CL = 50 pF) - Supports high-speed digital timing in real-time control loops.
Input Hysteresis	Schmitt-trigger on A and B - Rejects noise up to 30% of V_CC, eliminating false triggers in noisy environments.
Reset Function	Active-low, overriding - Forces immediate Q = LOW regardless of current pulse state, enabling fail-safe abort.
Fanout Capability	10 LSTTL loads - Drives multiple downstream logic gates without buffering in legacy TTL-compatible designs.

Pinout & Package

CD74HC123MG4 is housed in a 16-pin SOIC (D) package (5.3 mm × 10.2 mm, 1.75 mm height), RoHS-compliant, with NiPdAu lead finish and moisture sensitivity level 1 (260°C peak reflow).

Pin/Terminal	Circuit Role	Design Meaning
1A, 2A	Trailing-edge trigger input	Activates monostable on falling edge; Schmitt-triggered for noise rejection.
1B, 2B	Leading-edge trigger input	Activates monostable on rising edge; independent timing control per channel.
1R, 2R	Active-low reset input	Terminates output pulse immediately when pulled LOW; overrides ongoing timing.
1Q, 2Q	Inverted output	Complementary buffered output; drives LSTTL loads directly.
1Q̅, 2Q̅	Non-inverted output	Primary buffered output; matches standard monostable polarity convention.
1CX, 2CX	Timing capacitor connection	Connects external C_X; sets pulse width with R_X on pin 15/16.
1RXCX, 2RXCX	Timing resistor connection	Connects external R_X; forms RC network with C_X for precise t_W.
V_CC	Positive supply	2V–6V operation; decoupling required at pin 14 for stable timing.
GND	Ground reference	Common return for all signals and power; must be low-impedance.

Key Features

Feature	Design Value
Retriggerable operation	Enables dynamic pulse extension during active output - critical for variable-delay timing in motor control commutation.
Independent A/B edge selection	Eliminates need for external inverters to select rising/falling edge - reduces component count in signal conditioning stages.
Overriding active-low reset	Guarantees deterministic pulse termination under fault conditions - essential for safety-critical watchdog and interlock circuits.
Wide V_CC range (2V–6V)	Supports mixed-voltage system integration without level translators - simplifies power architecture in battery-powered instrumentation.
–55°C to +125°C operation	Validated performance across full military temperature range - suitable for downhole, aerospace, and engine-control applications.

Applications

Switch Debounce	Pulse Width Modulation (PWM) Timing
Use Scenario: Mechanical pushbutton inputs in industrial HMIs generate contact bounce lasting 5–20 ms, causing spurious logic transitions. IC Role / Device Role / Timing Role: CD74HC123MG4 acts as a hardware debounce filter, generating a clean, fixed-duration output pulse after first valid edge. Use Value: Eliminates firmware polling or software timers; ensures single, reliable edge per press using R_X = 100 kΩ, C_X = 100 nF (t_W ≈ 4.5 ms).	Use Scenario: Generating precise, adjustable PWM dead-time in half-bridge gate drivers to prevent shoot-through. IC Role / Device Role / Timing Role: CD74HC123MG4 provides programmable delay between complementary switch control signals via retriggerable monostable timing. Use Value: Achieves sub-microsecond timing accuracy (±2% match between channels) without microcontroller intervention or external crystal.
Logic Signal Retiming	Test Equipment Pulse Generation
Use Scenario: Synchronizing asynchronous signals from sensors into a clock domain with known setup/hold margins. IC Role / Device Role / Timing Role: CD74HC123MG4 retimes metastable inputs using edge-triggered monostable output as clean strobe. Use Value: Reduces MTBF for metastability-induced failures; propagation delay variation < ±15 ns over temperature ensures predictable timing alignment.	Use Scenario: Benchtop function generators require user-adjustable pulse widths for validating digital receiver response. IC Role / Device Role / Timing Role: CD74HC123MG4 serves as front-end pulse shaper, converting TTL trigger inputs into calibrated output pulses. Use Value: External RC network enables continuous pulse width tuning from 100 ns to 100 ms - covering logic analyzer, oscilloscope, and DUT stimulus requirements.

Switch Debounce

Pulse Width Modulation (PWM) Timing

Use Scenario: Mechanical pushbutton inputs in industrial HMIs generate contact bounce lasting 5–20 ms, causing spurious logic transitions.

IC Role / Device Role / Timing Role: CD74HC123MG4 acts as a hardware debounce filter, generating a clean, fixed-duration output pulse after first valid edge.

Use Value: Eliminates firmware polling or software timers; ensures single, reliable edge per press using R_X = 100 kΩ, C_X = 100 nF (t_W ≈ 4.5 ms).

Use Scenario: Generating precise, adjustable PWM dead-time in half-bridge gate drivers to prevent shoot-through.

IC Role / Device Role / Timing Role: CD74HC123MG4 provides programmable delay between complementary switch control signals via retriggerable monostable timing.

Use Value: Achieves sub-microsecond timing accuracy (±2% match between channels) without microcontroller intervention or external crystal.

Logic Signal Retiming

Test Equipment Pulse Generation

Use Scenario: Synchronizing asynchronous signals from sensors into a clock domain with known setup/hold margins.

IC Role / Device Role / Timing Role: CD74HC123MG4 retimes metastable inputs using edge-triggered monostable output as clean strobe.

Use Value: Reduces MTBF for metastability-induced failures; propagation delay variation < ±15 ns over temperature ensures predictable timing alignment.

Use Scenario: Benchtop function generators require user-adjustable pulse widths for validating digital receiver response.

IC Role / Device Role / Timing Role: CD74HC123MG4 serves as front-end pulse shaper, converting TTL trigger inputs into calibrated output pulses.

Use Value: External RC network enables continuous pulse width tuning from 100 ns to 100 ms - covering logic analyzer, oscilloscope, and DUT stimulus requirements.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74HC123DR	Same logic function, identical pinout, TI-manufactured; differs in tape-and-reel packaging (2500 pcs vs. 2500 pcs) and MSL rating (Level-1 vs. Level-1).	No functional difference; validated for same industrial temperature range and timing specs.	Select SN74HC123DR if requiring TI's current production revision with identical SOIC-16 footprint and timing behavior.
MC74HC123ADTR2G	Onsemi part; identical dual retriggerable monostable function, SOIC-16 package, but specifies VIH/VIL at VCC = 4.5V only (not 2V–6V range).	Limited to 4.5V–5.5V operation; not suitable for 3.3V or battery-backed 2V systems.	Choose MC74HC123ADTR2G only for 5V-only designs where second-source qualification is mandated.

Compared with SN74HC123DR and MC74HC123ADTR2G, the CD74HC123MG4 uniquely supports full 2V–6V operation and guaranteed –55°C to +125°C performance, making it the only option qualified for wide-input-voltage and extreme-temperature embedded control.

Availability

CD74HC123MG4 is available at Aetrix Electronics and suitable for industrial automation, test equipment, and aerospace subsystems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CD74HC123MG4 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 and embedded processing technologies, with decades of experience in high-reliability logic and timing solutions.

The CD74HC123MG4 belongs to TI's HC-series high-speed CMOS logic family, designed specifically for robust, low-power timing functions in harsh-environment applications including industrial control, defense systems, and automotive electronics.

FAQ

What is the minimum external timing capacitor value supported by the CD74HC123MG4?

The CD74HC123MG4 supports C_X = 0 pF as the minimum external timing capacitor value. This allows the device to operate with only an external resistor (R_X ≥ 5 kΩ) for ultra-short pulse widths down to approximately 100 ns at V_CC = 4.5V. The absence of mandatory capacitance simplifies board layout in high-speed applications where parasitic capacitance dominates timing.

Can the CD74HC123MG4 be used with a 3.3V supply voltage?

Yes, the CD74HC123MG4 operates reliably at 3.3V, as its specified supply range is 2V to 6V. At V_CC = 3.3V, input thresholds scale accordingly (VIH ≈ 2.1V, VIL ≈ 0.9V), and propagation delay increases to ~100 ns (max) - fully compatible with 3.3V LVTTL and LVCMOS interfaces without level translation.

How does the retriggering behavior of the CD74HC123MG4 differ from non-retriggerable monostables?

The CD74HC123MG4 extends its current output pulse width upon receiving a new trigger before t_W expires, whereas non-retriggerable monostables ignore subsequent triggers until the initial pulse completes. This enables adaptive timing in applications like rotary encoder interpolation or variable-frequency clock stretching, where pulse duration must respond dynamically to input event rate.

What is the purpose of separate A and B inputs on each monostable section of the CD74HC123MG4?

The A input triggers on the trailing (falling) edge, while the B input triggers on the leading (rising) edge - allowing edge-selective activation without external inverters. This dual-edge capability simplifies synchronization of asynchronous signals, such as capturing either edge of a quadrature encoder channel or selecting trigger polarity in data acquisition front-ends.

Is the CD74HC123MG4 pin-compatible with the CD74HCT123 series?

No, the CD74HC123MG4 is not pin-compatible with CD74HCT123 variants. While both share identical pinouts and package footprints, the HCT version requires 4.5V–5.5V supply and exhibits different input thresholds (VIH = 2V min, VIL = 0.8V max), making direct substitution invalid unless the system operates strictly at 5V with LSTTL-compatible drive levels.

CD74HC123MG4 Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74HC

Package/Case:: 16-SOIC (0.154", 3.90mm Width)

Packaging:: Bulk

Product Status:: Obsolete

Logic Type:: Monostable

Independent Circuits:: 2

Schmitt Trigger Input:: No

Propagation Delay:: 25 ns

Current - Output High, Low:: 5.2mA, 5.2mA

Voltage - Supply:: 2 V ~ 6 V

Operating Temperature:: -55°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 16-SOIC

CD74HC123MG4 FAQ

1.How can I place an order for CD74HC123MG4 through Aetrix?

Please submit a Request for Quotation (RFQ) for CD74HC123MG4 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 CD74HC123MG4 reliable?

The price and inventory of CD74HC123MG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HC123MG4 is usually 5 days.

3.What payment methods are accepted for CD74HC123MG4?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HC123MG4 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for CD74HC123MG4?

CD74HC123MG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your CD74HC123MG4 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 CD74HC123MG4?

For technical support, including CD74HC123MG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HC123MG4 requirements.

6.How does Aetrix verify that CD74HC123MG4 is sourced from the original manufacturer or authorized distributors?

All CD74HC123MG4 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 CD74HC123MG4 meets industry standards.

7.What is the process for return or replacement of CD74HC123MG4?

All CD74HC123MG4 units undergo pre-shipment inspection (PSI). If there is an issue with CD74HC123MG4, 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 CD74HC123MG4 part is unused and in its original packaging.

Return procedure for CD74HC123MG4:

1.Submit a request within 90 days.

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

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