STMicroelectronics 74LVQ138TTR

Overview

74LVQ138TTR from STMicroelectronics is a low-voltage CMOS 3-to-8 line decoder (inverting) with TTL-compatible outputs, operating from 2.0 V to 3.6 V. It features 5.5 ns typical propagation delay at 3.3 V, 12 mA minimum symmetrical output drive, and 4 µA maximum quiescent current at 25°C - optimized for low-noise, low-power 3.3 V address decoding in memory systems and bus interfaces.

For engineers reviewing the 74LVQ138TTR datasheet, 74LVQ138TTR pinout, 74LVQ138TTR application, or 74LVQ138TTR equivalent, key selection criteria include enable-input logic architecture (G1 active-high, G2A/G2B active-low), guaranteed PCI bus levels at 24 mA, 75 Ω transmission line driving capability, and latch-up immunity for industrial-grade reliability.

Technical Context

The 74LVQ138TTR implements a fully static, inverting 3-to-8 decoder with three independent enable inputs (G1, G2A, G2B) enabling cascaded memory address decoding without external gating. Its sub-micron C2MOS process ensures balanced tPLH ≅ tPHL propagation delays and <1.0 ns output-to-output skew across all eight Y0–Y7 outputs.

All inputs and outputs integrate 2 kV ESD protection, and DC specifications are guaranteed over –55°C to +125°C with 1.2 V data retention. The device supports dynamic switching on 75 Ω transmission lines and maintains symmetrical |IOH| = IOL = 12 mA (min) at VCC = 3.0 V - critical for clean signal integrity in high-density PCB layouts.

Key Specifications

Pinout & Package

TSSOP-16 package (JEDEC MO-153, 4.4 mm × 5.0 mm body, 0.65 mm pitch), lead-free and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LV138APWR and 74LVC138PW,118, the 74LVQ138TTR uniquely combines triple-enable architecture, lowest ICC (4 µA max), and guaranteed 24 mA PCI drive - making it optimal for cascaded, low-power, standards-compliant address decoding.

Availability

74LVQ138TTR is available at Aetrix Electronics and suitable for memory address decoding, PCI bus interfacing, industrial PLC I/O expansion, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74LVQ138TTR 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 74LVQ series targets low-voltage, low-noise 3.3 V logic applications - specifically engineered for memory subsystems, bus interfaces, and industrial controls demanding high noise immunity and extended temperature operation.

FAQ

What is the maximum clock frequency supported by the 74LVQ138TTR?

The 74LVQ138TTR is a combinational logic device with no internal clock; its maximum usable frequency depends on propagation delay and system setup/hold timing. With 5.5 ns typical tPD and balanced tPLH/tPHL, it reliably supports address decode operations up to ~100 MHz in well-terminated 3.3 V systems - verified via AC characteristics at CL = 50 pF and RL = 500 Ω.

Can the 74LVQ138TTR operate at 2.5 V supply?

Yes - the 74LVQ138TTR is fully specified from 2.0 V to 3.6 V. At VCC = 2.5 V, VIH is guaranteed ≥1.7 V and VIL ≤0.7 V, with tPD increasing to 8.0 ns (max) and output drive reducing to ±8 mA (min). All DC and AC parameters remain valid across this range per Table 5 and Table 6.

Is the 74LVQ138TTR pin-compatible with the 74HC138?

No - while functionally similar, the 74LVQ138TTR has identical pinout to the 74LS138 (G1 on pin 6, G2A/G2B on pins 4/5), whereas the 74HC138 places G2 on pin 5 only and lacks G2B. Additionally, the LVQ version operates down to 2.0 V and draws significantly less ICC than HC-series parts.

Does the 74LVQ138TTR require external pull-up resistors on outputs?

No - outputs are actively driven high or low; pull-ups are unnecessary. The device's symmetrical 12 mA (min) output sink/source capability ensures clean logic levels into standard CMOS loads. Pull-ups may be added only for specific wired-OR configurations, which are not supported by the 74LVQ138TTR's inverting open-collector–like behavior.