Texas Instruments 74LVC1G123DCTRG4

Overview

74LVC1G123DCTRG4 from Texas Instruments is a single retriggerable monostable multivibrator with Schmitt-trigger inputs, designed for 1.65V–5.5V V_CC operation. It delivers programmable output pulse duration via external R/C network, supports mixed-mode voltage translation, and features glitch-free power-up reset and I_off for live insertion-used in switch debouncing, timing control, and edge-sensitive event capture in embedded digital systems.

For engineers reviewing the 74LVC1G123DCTRG4 datasheet, 74LVC1G123DCTRG4 pinout, 74LVC1G123DCTRG4 application, or 74LVC1G123DCTRG4 equivalent, key selection criteria include retriggerable pulse width control (up to 100% duty cycle), 8 ns max t_pd at 3.3 V, Schmitt-trigger input hysteresis for jitter-free triggering on slow edges, and support for 5.5 V tolerant inputs across 1.65–5.5 V supply range.

Technical Context

The 74LVC1G123DCTRG4 implements a CMOS-based retriggerable monostable architecture where output pulse duration is determined by external R_ext and C_ext values connected to dedicated timing pins (Rext/Cext and Cext). Triggering occurs via three independent methods: A low → B rising, B high → A falling, or simultaneous A low/B high with CLR rising-each initiating or extending the Q output pulse.

Schmitt-trigger inputs on A and B provide ≥0.3×V_CC hysteresis, enabling robust operation with slow-rising/falling signals. The CLR input operates as both active-low override (terminating ongoing pulses) and rising-edge trigger, while I_off protection disables outputs during partial power-down to prevent back-drive current.

Key Specifications

Pinout & Package

74LVC1G123DCTRG4 is packaged in an 8-pin SSOP (DCT) with nominal body size 2.95 mm × 2.80 mm and 0.65 mm lead pitch. This RoHS-compliant surface-mount package supports automated assembly and provides thermal resistance of 220°C/W (junction-to-ambient).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC1G123DCUR and 74LVC1G123GW,125, the 74LVC1G123DCTRG4 offers the largest pad geometry and highest manufacturability margin in SSOP format-ideal for prototyping, medium-volume production, and legacy assembly lines without DSBGA/VSSOP support.

Availability

74LVC1G123DCTRG4 is available at Aetrix Electronics and suitable for switch debouncing, edge-sensitive event capture, PWM signal conditioning, and power sequencing control requiring stable component supply across industrial, computing, and consumer electronics programs.

Supply support for 74LVC1G123DCTRG4 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 over 90 years of innovation in power management, signal chain, and timing technologies.

The SN74LVC1G123 product line delivers compact, low-power retriggerable monostables for precise timing control in space- and power-constrained digital systems-from consumer audio interfaces to industrial PLC I/O modules.

FAQ

What is the minimum external timing capacitor value supported by the 74LVC1G123DCTRG4?

The 74LVC1G123DCTRG4 supports external timing capacitors down to 10 pF, as validated in Figure 5-7 (Minimum Retrigger Time vs Supply Voltage) and confirmed by operational data at 1.8 V with C_ext = 10 pF and R_ext = 1 kΩ. Lower values may reduce pulse width predictability due to parasitic capacitance dominance, so 10 pF is the practical lower limit for stable timing behavior in the 74LVC1G123DCTRG4.

Can the 74LVC1G123DCTRG4 operate with a 1.65 V supply and still meet its specified timing performance?

Yes, the 74LVC1G123DCTRG4 is fully characterized from 1.65 V to 5.5 V. At 1.65 V, t_pd is 18.5 ns (max, CL = 15 pF), and output pulse duration remains programmable via R/C-though timing resolution degrades slightly versus 3.3 V operation. All DC specs including I_off, VIH/VIL thresholds, and drive strength remain valid across the full 1.65–5.5 V range for the 74LVC1G123DCTRG4.

How does the CLR pin function in retriggerable mode for the 74LVC1G123DCTRG4?

In retriggerable mode, the CLR pin of the 74LVC1G123DCTRG4 serves dual roles: when driven low, it immediately terminates the ongoing Q output pulse; when held high, it enables standard A/B retriggering. It can also initiate a new pulse when A = low, B = high, and CLR transitions from low to high-providing a third independent trigger path without affecting A/B edge sensitivity in the 74LVC1G123DCTRG4.

Is the 74LVC1G123DCTRG4 compatible with 5 V logic inputs while operating from a 3.3 V supply?

Yes, the 74LVC1G123DCTRG4 accepts input voltages up to 5.5 V regardless of V_CC level, enabling direct connection to 5 V TTL or CMOS outputs when powered from 3.3 V. This input overvoltage tolerance eliminates level-shifting components and simplifies mixed-voltage system design for the 74LVC1G123DCTRG4.

What is the maximum achievable output pulse duration using external R/C components with the 74LVC1G123DCTRG4?

The 74LVC1G123DCTRG4 supports output pulse durations up to 100% duty cycle through continuous retriggering-effectively unlimited in practice. For single-shot operation, typical durations span nanoseconds to milliseconds (e.g., 100 ns with 1 kΩ/100 pF; 1 ms with 10 kΩ/0.1 µF). No hard upper limit is specified, as duration scales linearly with R_ext × C_ext product in the 74LVC1G123DCTRG4.