STMicroelectronics 74VHCT238ATTR

Overview

74VHCT238ATTR from STMicroelectronics is a high-speed CMOS 3-to-8 line decoder with TTL-compatible inputs, operating at 4.5–5.5 V, featuring 5.5 ns typical propagation delay, ±8 mA symmetrical output drive, and power-down input/output protection enabling 0–7 V input tolerance independent of VCC.

For engineers reviewing the 74VHCT238ATTR datasheet, 74VHCT238ATTR pinout, 74VHCT238ATTR application, or 74VHCT238ATTR equivalent, key selection criteria include enable-input cascade capability (G1, G2A, G2B), latch-up immunity, ESD robustness (2 kV), and compatibility with mixed-voltage 5 V ↔ 3 V interfacing in memory address decoding systems.

Technical Context

The device implements a non-inverting 3-to-8 binary decoder with three active-low enable inputs (G1, G2A, G2B) that collectively gate decoding: all outputs go low when G1 = low or either G2A/G2B = high. Inputs A, B, C accept TTL-level thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V) and tolerate up to 7 V regardless of VCC.

Propagation delays are balanced (tPLH ≈ tPHL) across all signal paths-A/B/C-to-Y, G1-to-Y, and G2A/G2B-to-Y-with worst-case tPD ≤ 11.5 ns at CL = 50 pF and VCC = 5.0 V. Output impedance symmetry ensures matched rise/fall behavior under load, critical for timing-critical address decode trees.

Key Specifications

Pinout & Package

TSSOP-16 package: 4.9 × 6.4 mm body, 0.65 mm pitch, 1.2 mm height, tape-and-reel packaging per order code 74VHCT238ATTR.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-to-8 decoder applications.

Compared with SN74HCT238N and 74LVX238MTR, the 74VHCT238ATTR uniquely combines 5 V operation, TTL compatibility, 0–7 V input tolerance, and TSSOP packaging-making it the sole choice for robust, mixed-voltage, surface-mount address decoding where reliability under supply transients matters.

Availability

74VHCT238ATTR is available at Aetrix Electronics and suitable for memory address decoding, peripheral selection logic, industrial PLC I/O expansion, and mixed-voltage interface bridge applications requiring stable component supply and long-term industrial lifecycle support.

Supply support for 74VHCT238ATTR 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 analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The VHCT logic family targets high-speed, low-power 5 V CMOS applications with TTL compatibility and enhanced robustness-specifically engineered for reliable address decoding and control logic in noise-prone industrial environments.

FAQ

Is the 74VHCT238ATTR compatible with 3.3 V input signals?

Yes - its TTL-compatible inputs accept VIH ≥ 2.0 V and VIL ≤ 0.8 V, so standard 3.3 V CMOS logic outputs (VOH ≈ 3.3 V, VOL ≈ 0 V) meet these thresholds. No level shifter is required for interfacing with 3.3 V controllers driving the A/B/C or enable pins.

What happens to outputs when VCC = 0 V?

Outputs remain in high-impedance state with no current flow due to built-in power-down protection. Inputs tolerate −0.5 V to +7.0 V regardless of VCC, preventing backfeeding or latch-up during power sequencing or hot-swap events.

Can multiple 74VHCT238ATTR devices be cascaded for larger decode functions?

Yes - the three enable inputs (G1, G2A, G2B) are designed for cascade: outputs from a higher-order decoder can drive enables of subordinate devices, supporting 4-to-16, 5-to-32, or wider address decode trees without additional gates.

Does this part support 100 % static logic testing?

Yes - all inputs and outputs feature 2 kV HBM ESD protection and are fully specified for DC parametrics across −55 °C to +125 °C. The truth table and DC electrical characteristics (VIH/VIL, VOH/VOL, II, ICC) are guaranteed over full temperature and voltage ranges.