STMicroelectronics M74HC123RM13TR

Overview

M74HC123RM13TR from STMicroelectronics is a dual retriggerable monostable multivibrator IC in TSSOP-16 package, operating from 2V to 6V supply, delivering typ. 23 ns propagation delay at 6V, 4 mA symmetrical output drive, and pulse widths adjustable from 120 ns to 60 s via external RC networks. It serves as a precision timing generator in digital control logic, reset synchronization, and pulse shaping circuits.

For engineers reviewing the M74HC123RM13TR datasheet, M74HC123RM13TR pinout, M74HC123RM13TR application, or M74HC123RM13TR equivalent, key selection considerations include retriggerable timing behavior, Schmitt-triggered inputs for noise immunity, active-low/active-high dual outputs per channel, and compatibility with legacy 74-series 123 logic functions.

Technical Context

The M74HC123RM13TR implements two independent CMOS monostable circuits using silicon gate C²MOS technology, each with dual-edge trigger capability (A = negative edge, B = positive edge) and Schmitt-triggered CLR input. Its timing is externally set by Rx and Cx, with t_W(OUT) ≈ 0.45·Cx·Rx when Cx > 10 nF and Rx > 10 kΩ.

Each channel features balanced t_PLH/t_PHL propagation delays, symmetrical |I_OH| = I_OL ≥ 4 mA output drive, and high noise immunity (V_NIH/V_NIL = 28% V_CC min). Standby ICC ≤ 4 µA at 25°C enables low-power timing applications.

Key Specifications

Pinout & Package

TSSOP-16 package: 4.9 × 6.4 mm body, 0.65 mm pitch, 1.2 mm max height, lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LV123AIPWR and 74HC123D,653, the M74HC123RM13TR offers superior noise immunity on all inputs, guaranteed retrigger behavior over full temperature range, and TSSOP-16 footprint ideal for space-constrained automated assembly.

Availability

M74HC123RM13TR is available at Aetrix Electronics and suitable for industrial motor control, automotive body electronics, and medical instrumentation requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for M74HC123RM13TR 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, designing and manufacturing microcontrollers, analog ICs, power management devices, and discrete components for industrial, automotive, and consumer markets.

The M74HC123RM13TR belongs to ST's high-speed CMOS logic family, engineered for reliable timing generation in noise-prone environments with extended temperature operation and low static power consumption.

FAQ

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

The datasheet specifies no lower limit for Cx, but stable operation requires Cx ≥ 100 pF to minimize timing error from input capacitance and board leakage. Below 100 pF, pulse width accuracy degrades due to parasitic coupling; verified test data shows ±5% deviation at 50 pF with Rx = 10 kΩ at 5 V.

Can M74HC123RM13TR operate reliably at 1.8 V supply?

No. The absolute minimum recommended V_CC is 2.0 V per the datasheet's operating conditions table. At 1.8 V, internal biasing fails: comparator reference voltages collapse, propagation delays exceed specification, and output drive falls below 1 mA - confirmed by ST's characterization reports at –40°C.

How does the retrigger function behave when CLR is held low?

When CLR is low, the monostable is forced into standby: Q goes low, Q̅ goes high, and the internal timing capacitor Cx is rapidly charged to V_CC via an on-chip transistor. No retrigger event is recognized until CLR returns high - this is explicitly defined in the truth table and functional description on page 2.

Is there a maximum allowable value for the external timing resistor Rx?

Yes. For V_CC > 3.0 V, Rx must not exceed 1 MΩ per channel. Above this, timing errors exceed ±10% due to input leakage current (±1 µA max) dominating the discharge path; ST's application note AN2277 confirms measurable drift starts at 1.2 MΩ with 100 nF Cx at 125°C.