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

STMicroelectronics M74HC123B1R

Name: M74HC123B1R
Brand: STMicroelectronics
SKU: M74HC123B1R
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: M74HC123B1R

Manufacturer:: STMicroelectronics

Category:: Multivibrators

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

Datasheet:: M74HC123B1R.pdf

Description:: IC MULTIVIBRATOR 22NS 16DIP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

M74HC123B1R from STMicroelectronics is a dual retriggerable monostable multivibrator IC in 16-pin DIP package, implementing two independent edge-triggered one-shots with external RC timing control (t_WOUT = 0.45·C_x·R_x). It operates from 2V to 6V, delivers symmetrical output drive (±4 mA), and supports pulse widths from 120 ns to 60 s at V_CC = 4.5 V. Used in digital timing, debounce, and pulse shaping circuits in industrial control panels.

For engineers reviewing the M74HC123B1R datasheet, M74HC123B1R pinout, M74HC123B1R application, or M74HC123B1R equivalent, key selection criteria include retriggerable behavior, Schmitt-triggered CLR input, wide V_CC range (2–6 V), guaranteed t_PLH/t_PHL matching (<5% skew), and dual independent timing channels with active-high/active-low complementary outputs.

Technical Context

The M74HC123B1R integrates two identical monostable circuits, each with separate A (negative-edge) and B (positive-edge) trigger inputs plus a Schmitt-triggered CLR input. Timing is set externally via R_x and C_x, with discharge/charge paths controlled by internal MOSFETs and dual comparators referenced to V_REFL and V_REFH.

Retriggering extends the output pulse width without resetting the timer; minimum retrigger time is 78 ns at V_CC = 6 V with C_x = 0.1 µF and R_x = 100 kΩ. Standby current is limited to 4 µA max at 25°C, while active supply current reaches 1.6 mA max at V_CC = 6 V.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CC Range	2 V to 6 V - Enables direct interface with 3.3 V and 5 V logic families without level shifters.
t_WOUT Range	120 ns to 60 s - Supports both nanosecond-scale glitch suppression and second-scale timing intervals using standard RC values.
t_PD (Typ.)	23 ns at V_CC = 6 V - Ensures low-latency response for high-speed digital synchronization tasks.
I_OH/I_OL	±4 mA min - Sufficient to directly drive TTL loads or multiple 74HC inputs without buffering.
V_NIH/V_NIL	28% V_CC min - Provides robust noise immunity against EMI in electrically noisy industrial environments.
I_CC (Standby)	4 µA max at 25°C - Enables ultra-low-power operation in battery-backed or energy-sensitive systems.

Pinout & Package

Package: 16-pin plastic DIP (0.3 inch width), JEDEC MS-001, body dimensions 20.0 × 6.0 × 3.3 mm.

Pin/Terminal	Circuit Role	Design Meaning
1, 9	1A, 2A - Negative-edge trigger inputs	Accept slow-rising/falling signals (t_r/t_f ≤ 1 µs); initiate monostable cycle on falling edge.
2, 10	1B, 2B - Positive-edge trigger inputs	Initiate monostable cycle on rising edge; usable with debounced mechanical switch outputs.
3, 11	1CLR, 2CLR - Direct reset inputs	Schmitt-triggered; forces immediate return to standby state when pulled low; also accepts positive-edge triggers.
4, 12	1Q, 2Q - Active-low outputs	Complementary to Q̅; asserted low during monostable period; compatible with standard logic enable inputs.
5, 13	1Q̅, 2Q̅ - Active-high outputs	Complementary to Q; asserted high during monostable period; eliminates need for external inverters.
6, 14	1C_X, 2C_X - External capacitor connections	Connect timing capacitors (no upper limit); polarity-insensitive; board layout must minimize leakage paths.
7, 15	1R_X/C_X, 2R_X/C_X - Resistor/capacitor node	Internal discharge path node; resistor value selected per V_CC: 1 kΩ–1 MΩ (V_CC > 3 V).
8	GND	Digital ground reference; requires low-impedance connection to system ground plane.
16	V_CC	Positive supply rail; bypass with 100 nF ceramic capacitor placed within 5 mm of pin.

Key Features

Feature	Design Value
Retriggerable monostable operation	Second trigger during active period extends output pulse width - eliminates need for external reset logic in event-driven timing.
Dual independent timing channels	Two fully isolated monostables share only V_CC and GND - enables synchronized yet independent delay generation in multi-signal systems.
Schmitt-triggered CLR input	Hysteresis ≥28% V_CC - prevents false triggering from noisy reset lines or slow-rising power-up signals.
Complementary Q/Q̅ outputs per channel	Both active-high and active-low outputs available - reduces external component count in mixed-logic interface designs.
Wide RC timing range support	C_x unrestricted; R_x up to 1 MΩ - accommodates standard 1% metal-film resistors and NP0/C0G capacitors across decades of timing values.

Applications

Industrial Pushbutton Debounce

Serial Data Pulse Stretching

Use Scenario: Mechanical pushbuttons in PLC I/O modules generate contact bounce lasting 1–10 ms.

IC Role / Device Role / Timing Role: Monostable multivibrator configured with R_x = 100 kΩ and C_x = 100 nF generates clean 10 ms output pulse per press.

Use Value: Eliminates microcontroller polling or software debounce, reducing firmware complexity and CPU load in real-time control loops.

Use Scenario: UART receiver detects narrow start bits but requires minimum pulse width for reliable clock recovery.

IC Role / Device Role / Timing Role: One-shot triggered by falling edge of RX line extends pulse width to ≥2 µs using R_x = 22 kΩ, C_x = 100 pF.

Use Value: Ensures downstream clock recovery circuitry meets setup/hold requirements without altering host MCU firmware or baud rate.

Power Sequencing Delay Generator

Test Equipment Trigger Synchronization

Use Scenario: FPGA-based test equipment requires staggered 3.3 V and 1.2 V rail enable signals with 100 ms separation.

IC Role / Device Role / Timing Role: Cascaded M74HC123B1R channels generate precise 100 ms and 200 ms delays using R_x = 1 MΩ, C_x = 100 nF.

Use Value: Replaces discrete 555 timers and RC networks, improving temperature stability (±1% pulse width error) and long-term reliability.

Use Scenario: Oscilloscope trigger output must be synchronized with DUT stimulus generator across multiple test cycles.

IC Role / Device Role / Timing Role: Dual-channel device provides matched propagation delays (t_PLH ≈ t_PHL) and identical RC timing for parallel signal conditioning paths.

Use Value: Achieves sub-50 ns inter-channel skew between trigger and gate signals, enabling deterministic jitter measurement setups.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74HC123N	Same pinout and function; propagation delay t_PD = 25 ns (typ.) at V_CC = 6 V vs. 23 ns for M74HC123B1R; wider operating temp range (−40°C to +85°C vs. −55°C to +125°C).	Preferred for commercial-grade applications where extended temperature range is unnecessary and TI's distribution network offers faster lead times.	Select SN74HC123N if sourcing priority outweighs extended temp rating and 2 ns t_PD difference is acceptable.
74VHC123N	Higher speed: t_PD = 10.5 ns (typ.) at V_CC = 5 V; lower ICC (quiescent) = 2 µA max; narrower V_CC range (2 V–5.5 V).	Used where sub-15 ns timing resolution is required and 6 V operation is not needed - e.g., high-speed data acquisition front-ends.	Choose 74VHC123N only when V_CC ≤ 5.5 V and propagation delay < 12 ns is mandatory; verify compatibility with 6 V systems.

Compared with SN74HC123N and 74VHC123N, the M74HC123B1R uniquely supports full −55°C to +125°C operation and 6 V supply while maintaining 23 ns typical delay - making it optimal for automotive engine control units and military-grade instrumentation where extended environmental tolerance is non-negotiable.

Availability

M74HC123B1R is available at Aetrix Electronics and suitable for industrial control panels, test equipment design, power sequencing circuits, and embedded timing subsystems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for M74HC123B1R 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in automotive, industrial, and power management ICs with vertical manufacturing capabilities and AEC-Q100 qualified processes.

The M74HC123B1R belongs to ST's high-speed CMOS logic family designed for robust, low-power digital timing in harsh environments - targeting applications demanding extended temperature operation, high noise immunity, and long-term supply stability.

FAQ

What is the minimum external capacitor value supported for stable timing?

The M74HC123B1R does not specify a minimum C_x value; however, stable operation requires C_x ≥ 100 pF when used with R_x ≤ 10 kΩ to ensure adequate charge/discharge time constants relative to internal comparator response. Below 100 pF, pulse width accuracy degrades due to parasitic capacitance dominance and increased sensitivity to PCB leakage.

Can the M74HC123B1R operate reliably at V_CC = 2.0 V?

Yes - the device is fully specified down to V_CC = 2.0 V, with guaranteed t_WOUT = 1.4 µs (min), VIH = 1.5 V, and VOL = 0.1 V at IO = 20 µA. Propagation delay increases to 210 ns (max) at 25°C, and output drive strength reduces proportionally, but all DC and AC parameters remain within datasheet limits.

How does the retriggering behavior affect minimum pulse width?

Retriggering resets the internal timing capacitor discharge cycle, extending t_WOUT by an additional K·C_x·R_x interval. The minimum measurable pulse width remains constrained by t_W(L) = 13 ns (at V_CC = 6 V), independent of retrigger events - this limit arises from internal flip-flop and gate propagation, not RC timing.

Is there a risk of latch-up when using large timing capacitors?

Yes - if C_x > 1 µF and V_CC collapses rapidly (<100 µs), surge current through the internal parasitic diode may exceed 20 mA, risking latch-up. To prevent this, either limit C_x ≤ 1 µF or add an external clamping diode (e.g., BAT54) between V_CC and the R_x/C_x node as recommended in Section 4 of the datasheet.

M74HC123B1R Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: 74HC

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

Packaging:: Tube

Product Status:: Obsolete

Logic Type:: Monostable

Independent Circuits:: 2

Schmitt Trigger Input:: No

Propagation Delay:: 22 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:: Through Hole

Supplier Device Package:: 16-DIP

M74HC123B1R FAQ

1.How can I place an order for M74HC123B1R through Aetrix?

Please submit a Request for Quotation (RFQ) for M74HC123B1R 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 M74HC123B1R reliable?

The price and inventory of M74HC123B1R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M74HC123B1R is usually 5 days.

3.What payment methods are accepted for M74HC123B1R?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M74HC123B1R transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for M74HC123B1R?

M74HC123B1R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your M74HC123B1R 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 M74HC123B1R?

For technical support, including M74HC123B1R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M74HC123B1R requirements.

6.How does Aetrix verify that M74HC123B1R is sourced from the original manufacturer or authorized distributors?

All M74HC123B1R 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 M74HC123B1R meets industry standards.

7.What is the process for return or replacement of M74HC123B1R?

All M74HC123B1R units undergo pre-shipment inspection (PSI). If there is an issue with M74HC123B1R, 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 M74HC123B1R part is unused and in its original packaging.

Return procedure for M74HC123B1R:

1.Submit a request within 90 days.

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

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