Texas Instruments SN74LV138ADGVR

Overview

SN74LV138ADGVR from Texas Instruments is a 3-line to 8-line decoder/demultiplexer in TVSOP-16 package, operating from 2 V to 5.5 V, with 9.5 ns max propagation delay at 5 V, Ioff-enabled partial-power-down capability, and mixed-mode voltage interface support. It selects one of eight active-low outputs using three binary address inputs (A0–A2) and three enable inputs (G2, G0, G1), enabling memory decoding and output expansion in low-voltage embedded systems.

For engineers reviewing the SN74LV138ADGVR datasheet, SN74LV138ADGVR pinout, SN74LV138ADGVR application, or SN74LV138ADGVR equivalent, key selection considerations include its 3.3 V/5 V dual-rail compatibility, ground-bounce and undershoot performance (VOLP < 0.8 V, VOHV > 2.3 V at 3.3 V), thermal pad presence in RGY/BQB packages (not applicable to DGVR), and strict input transition rate requirements (20 ns/V min at 5 V).

Technical Context

The SN74LV138ADGVR implements standard CMOS logic with balanced push-pull outputs and dedicated Ioff circuitry that disables all outputs when VCC = 0 V, preventing backflow current during power sequencing. Its enable architecture uses two active-low (G0, G1) and one active-high (G2) inputs to minimize external logic for cascaded decoding.

Functionally, it operates as a positive-logic 3:8 decoder with active-low outputs: only one Yx line goes low per valid A2:A0 combination when all enables are asserted; all outputs remain high otherwise. Input thresholds scale with VCC (VIH = 0.7×VCC, VIL = 0.3×VCC), supporting interoperability across 2.5 V, 3.3 V, and 5 V domains without level shifters.

Key Specifications

Pinout & Package

SN74LV138ADGVR is packaged in a 16-pin TVSOP (DGV) with body size 3.60 mm × 4.40 mm and exposed thermal pad (not electrically connected). Pin 1 is marked by a dot; top-view orientation follows JEDEC MO-153.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC138N and 74LVC138PW, SN74LV138ADGVR provides superior noise immunity (VOLP/VOHV specified), guaranteed Ioff behavior, and optimized 3.3 V timing - making it preferred for industrial and automotive subsystems requiring robust power sequencing and EMI resilience.

Availability

SN74LV138ADGVR is available at Aetrix Electronics and suitable for LED matrix control, 7-segment display multiplexing, and memory address decoding requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for SN74LV138ADGVR 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and logic solutions, with over 50 years of innovation in high-reliability logic families.

The SN74LV138ADGVR belongs to TI's LV (Low-Voltage) logic family, designed specifically for robust 2 V–5.5 V operation in space-constrained, thermally demanding applications such as portable instrumentation and automotive body electronics.

FAQ

What is the maximum clock frequency supported by SN74LV138ADGVR?

SN74LV138ADGVR does not operate on a clock; it is a combinational logic device. Its speed is defined by propagation delay: 9.5 ns max at 5 V with 15 pF load. This corresponds to a theoretical maximum toggle rate of ~105 MHz under ideal conditions, but real-world system timing depends on address stability, enable assertion, and load capacitance. The SN74LV138ADGVR datasheet specifies no clock parameter because it has no internal clock or state elements.

Does SN74LV138ADGVR support 1.8 V operation?

No, SN74LV138ADGVR does not support 1.8 V operation. Its absolute minimum VCC is 2 V per the Recommended Operating Conditions table, and electrical characteristics (VIH, VIL, VOL, VOH, tpd) are not characterized below 2 V. Attempting to operate SN74LV138ADGVR at 1.8 V may result in undefined logic states, excessive ICC, or failure to meet timing specifications.

Can SN74LV138ADGVR outputs be wired together for higher current drive?

No, SN74LV138ADGVR outputs must never be directly paralleled. Its outputs are totem-pole CMOS with active pull-up and pull-down stages. Connecting two outputs risks shoot-through current if one drives high while the other drives low, potentially damaging the SN74LV138ADGVR. For higher drive, use external buffers or select a part with higher-rated outputs like 74LVC138.

Is the thermal pad on SN74LV138ADGVR electrically connected?

No, the thermal pad on SN74LV138ADGVR (TVSOP-16 package) is not electrically connected to any internal node. Per TI's package drawing and datasheet Table 5-1, the thermal pad is designated "PAD" with no signal assignment. It should be soldered to a PCB thermal plane for improved heat dissipation but left floating electrically - no connection to VCC or GND is required or recommended.

How do I handle unused inputs on SN74LV138ADGVR?

All unused inputs on SN74LV138ADGVR must be terminated to a valid logic level - either VCC or GND - to prevent floating nodes that cause excessive ICC, oscillation, or erratic output behavior. TI recommends 10-kΩ pull-up or pull-down resistors for inputs that may be un-driven during certain modes. Direct connection is acceptable for permanently unused inputs. Leaving any input (e.g., A2, G1) unconnected violates the Recommended Operating Conditions and risks functional failure.