STMicroelectronics M74HC257B1R

Overview

M74HC257B1R from STMicroelectronics is a high-speed CMOS quad 2-channel multiplexer with 3-state outputs, non-inverting logic, common SELECT and active-low ENABLE (OE) control, 11 ns typical propagation delay at 6 V, ±6 mA output drive, and operation from 2 V to 6 V supply. It routes four independent A/B data pairs to corresponding Y outputs in industrial control I/O expansion.

For engineers reviewing the M74HC257B1R datasheet, M74HC257B1R pinout, M74HC257B1R application, or M74HC257B1R equivalent, key selection criteria include 3-state output timing (tPZL/tPLZ), input noise immunity (28% VCC), symmetrical drive strength, wide VCC range compatibility, and DIP-16 package availability for through-hole prototyping and legacy board replacement.

Technical Context

The M74HC257B1R implements four independent 2:1 multiplexers sharing one SELECT line and one active-low OE input, enabling simultaneous channel selection and global output enable/disable. Each multiplexer passes A-input when SELECT = LOW and B-input when SELECT = HIGH, with no inversion.

All inputs feature silicon-gate C2MOS protection against ESD and transient overvoltage; outputs exhibit matched |IOH| = |IOL| ≥ 6 mA at VCC = 4.5 V and 6 V, ensuring consistent rise/fall times and balanced tPLH ≅ tPHL propagation delays across temperature ranges from –55 °C to +125 °C.

Key Specifications

Pinout & Package

Package: Plastic DIP-16 (0.300" width), JEDEC MS-001, body dimensions 20.0 × 8.5 mm, lead pitch 2.54 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 2:1 multiplexer applications.

Compared with SN74HC257N and CD74HC257E, the M74HC257B1R offers broader temperature qualification (–55 °C to +125 °C), tighter propagation delay consistency (11 ns typ.), and documented input protection for harsh environments-making it preferred for mission-critical embedded control.

Availability

M74HC257B1R is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, legacy system bus interface, and test equipment signal routing requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for M74HC257B1R 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 analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The M74HC257B1R belongs to the 74HC high-speed CMOS logic family, engineered for low-power, noise-immune digital signal routing in space-constrained and thermally demanding embedded systems.

FAQ

What is the maximum recommended operating voltage for M74HC257B1R?

The absolute maximum VCC rating is +7 V, but the recommended operating range is strictly 2 V to 6 V per datasheet Section 3. Exceeding 6 V risks accelerated parametric drift and reduced long-term reliability, even if functional at 6.5 V in short-term bench tests. Operation at 6 V delivers optimal speed–power trade-off with 11 ns typical propagation delay.

Does M74HC257B1R support hot insertion or live bus connection?

No-M74HC257B1R lacks explicit hot-swap or live-insertion protection features. Its input structure includes clamping diodes referenced to VCC and GND, but these are rated only for ESD (±2 kV HBM) and transient suppression-not sustained overvoltage during live connection. Always power-cycle the board before inserting or removing the device to avoid latch-up or permanent damage.

How does the 3-state output behavior interact with OE and SELECT inputs?

When OE = HIGH, all Y outputs enter high-impedance regardless of SELECT or A/B input states. When OE = LOW, outputs follow SELECT: Y = A if SELECT = LOW, Y = B if SELECT = HIGH. The 3-state transition occurs within 10–28 ns (tPZL/tPLZ), and output drive strength remains symmetrical (|IOH| = |IOL| ≥ 6 mA) in both logic states.

Can M74HC257B1R operate reliably at –55 °C?

Yes-the device is fully characterized and guaranteed to meet all AC/DC specifications across –55 °C to +125 °C, including propagation delay (tPLH/tPHL ≤ 26 ns at –55 °C, VCC = 6 V), output drive (IOL/IOH ≥ 6 mA), and input thresholds (VIH/VIL = 28% VCC). This makes it suitable for aerospace, downhole, and polar-environment applications where extended cold operation is mandatory.