STMicroelectronics M74HCT125RM13TR

Overview

M74HCT125RM13TR from STMicroelectronics is a high-speed CMOS quad 3-state bus buffer with TTL-compatible inputs, 13 ns typical propagation delay at 4.5 V, ±6 mA symmetrical output drive, and 4 µA max quiescent current at 25°C - used in bidirectional data bus isolation and level translation between HCMOS/TTL systems.

For engineers reviewing the M74HCT125RM13TR datasheet, M74HCT125RM13TR pinout, M74HCT125RM13TR application, or M74HCT125RM13TR equivalent, key selection criteria include 3-state enable timing (tPZL/tPLZ ≤36 ns), input voltage thresholds (VIH ≥2.0 V, VIL ≤0.8 V), rail-to-rail output swing under load, and TSSOP14 package thermal and routing constraints.

Technical Context

The device implements four independent non-inverting buffers, each with a dedicated active-low 3-state enable input (G) that places the corresponding Y output in high-impedance when asserted high. All inputs feature diode-based ESD protection and tolerate overvoltage up to VCC + 0.5 V.

It operates across full industrial temperature range (–55°C to +125°C) with guaranteed DC specs at VCC = 4.5–5.5 V, including VOH ≥4.13 V at IOH = –6 mA and VOL ≤0.40 V at IOL = 6 mA, enabling robust interfacing with legacy TTL loads.

Key Specifications

Pinout & Package

TSSOP14 (Thin Shrink Small Outline Package, 14-pin), 4.9 × 6.4 mm body, 0.65 mm pitch, exposed pad not present, JEDEC MO-153 compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 3-state buffer applications.

Compared with SN74HCT125PW and 74VHC125FT, the M74HCT125RM13TR uniquely balances TTL input compatibility, industrial temperature support, and proven field reliability in mixed-voltage industrial control systems - making it optimal for drop-in upgrades and long-lifecycle deployments.

Availability

M74HCT125RM13TR is available at Aetrix Electronics and suitable for industrial data acquisition, automotive body control modules, programmable logic controller backplanes, and test equipment signal routing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for M74HCT125RM13TR 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, designing and manufacturing silicon solutions for automotive, industrial, and power management applications.

The M74HCT125 belongs to ST's high-speed HCT logic family, engineered specifically for seamless interoperability between CMOS microcontrollers and legacy TTL subsystems in harsh-environment control systems.

FAQ

What is the maximum clock frequency supported by M74HCT125RM13TR?

The device does not operate as a clocked element but as a combinational buffer. Its usable data rate depends on propagation delay and load: with tPD = 13 ns (typ.) and CL = 50 pF, it reliably supports asynchronous bus toggling up to ~30 MHz under light capacitive loading. System-level timing must account for worst-case 32 ns delay across temperature and voltage.

Can M74HCT125RM13TR drive a 50 Ω transmission line directly?

No - its 6 mA output drive corresponds to ~830 Ω effective impedance at 5 V, far above 50 Ω. Direct 50 Ω driving would cause severe overshoot, ringing, and excessive current draw (>100 mA). Use series termination (33–47 Ω) or dedicated line drivers for controlled-impedance traces.

Is the TSSOP14 package RoHS-compliant and lead-free?

Yes - M74HCT125RM13TR uses a lead-free, halogen-free TSSOP14 package conforming to RoHS Directive 2011/65/EU and JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1), with peak reflow temperature rated at 260°C.

Does the device support partial power-down (e.g., VCC = 0 V while inputs biased)?

No - applying input voltages outside GND–VCC violates Absolute Maximum Ratings. With VCC = 0 V, VI must remain between –0.5 V and 0 V. Input diodes will conduct if VI > 0.5 V, risking latch-up or damage. Always power VCC before asserting inputs.