Texas Instruments SN74LV138ATDBR

Overview

SN74LV138ATDBR from Texas Instruments is a 3-line to 8-line decoder/demultiplexer in SSOP-16 package, operating from 4.5 V to 5.5 V, with max propagation delay of 7.6 ns at 5 V, TTL-voltage-compatible inputs, and Ioff partial-power-down support. It enables high-speed memory decoding and data routing in industrial control and embedded logic systems.

For engineers reviewing the SN74LV138ATDBR datasheet, SN74LV138ATDBR pinout, SN74LV138ATDBR application, or SN74LV138ATDBR equivalent, key selection criteria include enable-input logic (G1 active-high, G2A/G2B active-low), output drive capability (±12 mA), latch-up immunity (>250 mA), and thermal performance (θJA = 82°C/W for DB package).

Technical Context

The SN74LV138ATDBR implements positive-logic decoding with three binary select inputs (A, B, C) and three enable inputs (G1, G2A, G2B), where only one of eight active-low outputs (Y0–Y7) is asserted per valid input combination. Its architecture supports cascading via enable inputs - G2A and G2B can serve as data inputs for demultiplexing, and G1 allows hierarchical expansion without external inverters.

Designed for mixed-mode voltage operation, it tolerates input voltages up to 5.5 V independent of VCC, and its Ioff circuitry disables outputs during partial power-down to prevent backflow current. Absolute maximum ratings include 7 V on VCC and VI, with ESD protection exceeding 2000-V HBM and 1000-V CDM.

Key Specifications

Pinout & Package

SN74LV138ATDBR uses a 16-pin SSOP (Shrink Small Outline Package) with 0.65 mm pitch, 7.4 mm × 5.3 mm body size, and 2.0 mm max height per JEDEC MO-150. Pin 1 is located in Quadrant Q1 per tape-and-reel orientation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC138DR and 74LVC138AD,118, the SN74LV138ATDBR uniquely balances 5-V TTL compatibility, sub-8-ns speed, Ioff safety, and full automotive temperature range - making it the only option qualified for industrial hot-swap and mixed-rail 5-V logic systems.

Availability

SN74LV138ATDBR is available at Aetrix Electronics and suitable for industrial PLCs, automotive body controllers, and high-reliability embedded memory systems requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for SN74LV138ATDBR 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 decades of expertise in high-reliability interface and signal-path ICs.

The SN74LV138ATDBR belongs to TI's LV (Low-Voltage) logic family, engineered for robust 5-V operation with TTL compatibility, fast propagation, and enhanced power-down safety - targeting industrial, automotive, and communications infrastructure applications.

FAQ

What is the maximum propagation delay of the SN74LV138ATDBR at 5 V?

The SN74LV138ATDBR has a maximum propagation delay (tpd) of 7.6 ns at VCC = 5 V, CL = 15 pF, and TA = –40°C to 125°C. This value is measured from any address or enable input transition to the corresponding Yx output transition, ensuring predictable timing in high-speed memory decode paths. The SN74LV138ATDBR maintains this specification across its full industrial temperature range.

Does the SN74LV138ATDBR support partial power-down operation?

Yes, the SN74LV138ATDBR includes Ioff circuitry that disables all outputs when VCC = 0 V, limiting Ioff to ≤5 µA over 0–5.5 V at VI or VO. This feature prevents damaging current backflow in multi-rail systems during power sequencing or hot-swap events. The SN74LV138ATDBR is fully specified for partial-power-down per datasheet Section 6.3.

What are the enable-input logic polarities for the SN74LV138ATDBR?

The SN74LV138ATDBR uses three enable inputs: G1 is active-high, while G2A and G2B are both active-low. All three must be asserted simultaneously (G1 = high, G2A = low, G2B = low) for decoding to occur. The SN74LV138ATDBR leverages this arrangement to simplify cascading - for example, G2A can serve as a data input in demultiplexer mode without external inverters.

Can the SN74LV138ATDBR interface directly with 3.3-V microcontrollers?

No - the SN74LV138ATDBR is designed for 4.5–5.5 V operation and requires TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max). While its inputs tolerate up to 5.5 V, a 3.3-V MCU cannot reliably drive VIH at 2.0 V across process/voltage/temperature corners without margin loss. For 3.3-V systems, TI recommends the 74LVC138AD,118 instead. The SN74LV138ATDBR is strictly a 5-V solution.

What package type and dimensions does the SN74LV138ATDBR use?

The SN74LV138ATDBR uses a 16-pin SSOP (Shrink Small Outline Package) with JEDEC MO-150 registration, designated DB package. Its dimensions are 7.4 mm × 5.3 mm × 2.0 mm max height, 0.65 mm lead pitch, and pin 1 located in Quadrant Q1 per tape-and-reel orientation. The SN74LV138ATDBR's θJA is 82°C/W, requiring appropriate PCB copper area for thermal management at full load.