Texas Instruments CD74HCT123M96

Overview

CD74HCT123M96 from Texas Instruments is a dual retriggerable monostable multivibrator with independent resets, designed for precise pulse generation and timing control in digital systems. It operates from 4.5V to 5.5V, features Schmitt-trigger inputs on both A and B trigger pins, supports trailing-edge (A) and leading-edge (B) triggering, and delivers buffered Q and Q̅ outputs. It is used in debounce circuits, event timing, and programmable delay generation where temperature-stable pulse widths from external RC networks are required.

For engineers reviewing the CD74HCT123M96 datasheet, CD74HCT123M96 pinout, CD74HCT123M96 application, or CD74HCT123M96 equivalent, key selection considerations include its HCT-level LSTTL input compatibility (VIH ≥ 2V, VIL ≤ 0.8V), wide -55°C to +125°C operating range, SOIC-16 package, retriggerable behavior, and reset-override capability for dynamic pulse termination.

Technical Context

The CD74HCT123M96 implements two independent monostable multivibrators, each with separate A (trailing-edge), B (leading-edge), and R (active-low reset) inputs. Pulse width t_W = 0.45·R_XC_X at V_CC = 5V, enabling adjustable delays from nanoseconds to milliseconds via external resistor and capacitor. Retriggering extends the output pulse without requiring full timeout.

Its HCT logic family ensures direct compatibility with legacy LSTTL inputs while delivering CMOS power efficiency. The device includes Schmitt-trigger inputs for noise immunity, balanced propagation delays (t_PLH/t_PHL ≤ 90 ns max at V_CC = 4.5V, CL = 50 pF), and fanout of 10 LSTTL loads over full temperature range.

Key Specifications

Pinout & Package

CD74HCT123M96 is housed in a 16-pin SOIC (D) package, 7.5 mm × 10.3 mm body size, 1.27 mm pitch, RoHS-compliant NiPdAu/Sn lead finish, MSL Level-1 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HC123M96 and SN74LVC1G123DBVR, the CD74HCT123M96 uniquely combines LSTTL-compatible inputs, dual independent monostables with per-channel resets, and industrial temperature support - making it the only option among the three that guarantees plug-and-play replacement in legacy 5V TTL-logic systems requiring two synchronized timing channels.

Availability

CD74HCT123M96 is available at Aetrix Electronics and suitable for industrial control, aerospace avionics, and test equipment applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HCT123M96 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 logic solutions, with decades of heritage in high-reliability logic families.

The CD74HCT123M96 belongs to TI's legacy HCT logic product line, engineered specifically for seamless migration from bipolar TTL systems while delivering CMOS power efficiency and robustness across harsh environments.

FAQ

What is the minimum external resistor value recommended for CD74HCT123M96?

The datasheet specifies a typical minimum external resistance R_X of 5 kΩ for CD74HCT123M96. Using values below this may cause timing inaccuracies or increased sensitivity to leakage currents. For stable operation across -55°C to +125°C, TI recommends R_X ≥ 10 kΩ with standard 1% metal-film resistors. This ensures consistent t_W = 0.45·R_XC_X performance and avoids excessive current draw through the RXCX pin.

Can CD74HCT123M96 operate with a 3.3V supply?

No, CD74HCT123M96 is not rated for 3.3V operation. Its HCT family specification mandates a supply voltage range of 4.5V to 5.5V. At 3.3V, input thresholds (VIH ≥ 2.0V, VIL ≤ 0.8V) become unmet, resulting in unreliable logic recognition and potential metastability. For 3.3V systems, consider the pin-compatible CD74HC123M96 or SN74LVC1G123DBVR instead.

How does the retriggering behavior of CD74HCT123M96 differ from non-retriggerable monostables?

Unlike non-retriggerable monostables that ignore subsequent triggers until the initial pulse completes, CD74HCT123M96 extends the current output pulse width upon each valid A or B edge received during an active output. This allows dynamic pulse stretching - for example, holding Q high as long as periodic triggers arrive within the retrigger window (t_rT ≈ 76 ns min at V_CC = 4.5V). This behavior is intrinsic to the '123 series and explicitly enabled by its internal architecture.

Is the CD74HCT123M96 pinout compatible with CD74HC423M96?

No, CD74HCT123M96 and CD74HC423M96 share identical pinouts and package footprints (SOIC-16), but they differ functionally: the '123 supports retriggering and reset-override, while the '423 is non-retriggerable and lacks reset override. Though physically interchangeable, substituting one for the other will alter timing behavior - e.g., a '423 will ignore mid-pulse triggers and cannot be terminated early by R. Always verify functional requirements before interchange.

What is the maximum recommended external capacitance for CD74HCT123M96?

The datasheet does not specify an absolute maximum C_X, but practical limits arise from leakage, parasitic resistance, and timing accuracy. For stable operation across -55°C to +125°C, TI recommends C_X ≤ 10 µF using X7R or C0G dielectrics. Larger values increase sensitivity to dielectric absorption and leakage-induced timing drift. At C_X = 10 nF and R_X = 100 kΩ, CD74HCT123M96 achieves t_W ≈ 450 µs with ±2% match between channels - a verified design point in the datasheet.