Texas Instruments SN74LV138ANSR

Overview

SN74LV138ANSR from Texas Instruments is a 3-line to 8-line decoder/demultiplexer IC operating from 2 V to 5.5 V, delivering 9.5 ns maximum propagation delay at 5 V, supporting mixed-mode voltage operation across all ports, and featuring Ioff for partial-power-down mode. It is used in LED matrix control and memory address decoding where low-voltage compatibility and deterministic output enable sequencing are required.

For engineers reviewing the SN74LV138ANSR datasheet, SN74LV138ANSR pinout, SN74LV138ANSR application, or SN74LV138ANSR equivalent, key selection criteria include its dual active-low + single active-high enable architecture, 16-pin SOIC (D) package with validated 16-pin terminal mapping, guaranteed VOLP & VOHV performance at 3.3 V, and direct support for 8-bit data routing without external inverters.

Technical Context

The SN74LV138ANSR implements a positive-logic 3-to-8 decoder with three binary select inputs (A0–A2) and three enable inputs (G2, G0, G1), where G0 and G1 are active-low and G2 is active-high-enabling hierarchical expansion up to 32 lines using only one external inverter. Its CMOS input structure requires fast edge rates (≤20 ns/V at 5 V) and mandates termination of unused inputs to VCC or GND.

Output behavior follows standard balanced push-pull CMOS: outputs drive high or low actively (not open-drain), with VOL ≤ 0.55 V at 12 mA/4.5 V and VOH ≥ 3.8 V under same conditions; Ioff circuitry disables all outputs when VCC = 0 V, limiting leakage to ≤5 μA per terminal during power-down.

Key Specifications

Pinout & Package

SN74LV138ANSR is supplied in a 16-pin SOIC (D) package measuring 9.90 mm × 3.91 mm, with gull-wing leads and standard 1.27 mm pitch. Pin 1 is marked by a beveled corner or notch; thermal pad is absent (non-exposed).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar decoder/demultiplexer applications.

Compared with 74HC138DR and SN74LVC138APWR, SN74LV138ANSR offers optimal balance of industrial temperature range, proven 2–5.5 V interoperability, and Ioff-enabled safe power-down-making it preferred for legacy 3.3 V/5 V industrial control boards where layout reuse and long-term availability are prioritized.

Availability

SN74LV138ANSR is available at Aetrix Electronics and suitable for LED matrix control, memory address decoding, and industrial I/O expansion requiring stable component supply across extended temperature ranges and multi-voltage system integration.

Supply support for SN74LV138ANSR 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 SN74LV138ANSR belongs to TI's LV (Low-Voltage) logic series, designed specifically for robust 2–5.5 V operation in industrial automation, test equipment, and legacy-compatible embedded systems where mixed-voltage interfacing and power-down safety are essential.

FAQ

What is the maximum propagation delay of the SN74LV138ANSR at 3.3 V?

The SN74LV138ANSR has a maximum propagation delay of 13.5 ns at VCC = 3.3 V with 15 pF load capacitance and TA = 25°C, as specified in Section 6.7 of the official datasheet. This value applies to transitions from any address or enable input to any Y output. At 50 pF load, the max tpd increases to 18 ns under identical conditions. These figures ensure reliable timing in 3.3 V microcontroller peripheral decoding applications.

Does the SN74LV138ANSR support partial-power-down mode?

Yes, the SN74LV138ANSR supports partial-power-down mode via its Ioff feature. When VCC = 0 V, all outputs are disabled and leakage current is limited to ≤5 μA per terminal, preventing damaging current backflow. This behavior is explicitly characterized in Section 6.5 of the datasheet and makes SN74LV138ANSR suitable for hot-swap backplanes and battery-backed subsystems where power sequencing matters.

What package type does SN74LV138ANSR use, and is it RoHS compliant?

SN74LV138ANSR uses the SOIC-16 (D) package, measuring 9.90 mm × 3.91 mm with 1.27 mm lead pitch. Per TI's official packaging documentation, this variant is RoHS compliant and lead-free, with NiPdAu lead finish. The "NSR" suffix confirms tape-and-reel packaging for automated assembly, and the device meets JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1) requirements.

Can SN74LV138ANSR drive 5 V logic inputs while operating at 3.3 V VCC?

Yes, SN74LV138ANSR supports mixed-mode voltage operation: its inputs tolerate 0–5.5 V regardless of VCC setting. When powered at 3.3 V, it can safely accept 5 V control signals on A0–A2, G0, G1, or G2. Outputs swing from near-GND to near-VCC (3.3 V), so driving 5 V TTL inputs may require external pull-ups or level translators unless the receiving device specifies VIH ≤ 2.0 V.

How many enable inputs does the SN74LV138ANSR have, and what are their polarities?

The SN74LV138ANSR has three enable inputs: G2 (active-high), G0 (active-low), and G1 (active-low). All three must be satisfied simultaneously for any Y output to activate - G2 must be HIGH while both G0 and G1 must be LOW. This asymmetric enable structure reduces external logic count in cascaded decoder configurations, as confirmed in the functional block diagram and truth table of the SN74LV138ANSR datasheet.