Texas Instruments SN74ACT138PWRQ1

Overview

SN74ACT138PWRQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive 3-to-8 decoder/demultiplexer with TTL-compatible CMOS inputs, operating from 4.5V to 5.5V, delivering ±24mA continuous output drive, 10.2ns propagation delay (VCC = 5V, CL = 50pF), and supporting 50Ω transmission line driving in vehicle body control modules and powertrain interface circuits.

For engineers reviewing the SN74ACT138PWRQ1 datasheet, SN74ACT138PWRQ1 pinout, SN74ACT138PWRQ1 application, or SN74ACT138PWRQ1 equivalent, key selection considerations include automotive temperature range (-40°C to +125°C), dual active-low and single active-high enable architecture, wettable-flank TSSOP-16 packaging, balanced push-pull output capability, and compatibility with legacy TTL logic levels in safety-critical signal routing.

Technical Context

The SN74ACT138PWRQ1 implements a positive-logic 3-input binary decoder with three enable inputs (G2, G1 active low, G0 active low) controlling eight active-low outputs (Y0–Y7). Its function table defines strict priority among strobes: any high on G0 or G1, or low on G2, forces all outputs high regardless of address inputs A0–A2.

It uses TTL-compatible CMOS input structure with VIH(min) = 2.0V and VIL(max) = 0.8V, enabling direct interfacing with legacy 5V TTL sources while maintaining CMOS-level static power efficiency (ICC ≤ 80µA at 5.5V). Output stage is balanced push-pull, supporting both sourcing and sinking up to ±24mA continuously and ±75mA in short bursts.

Key Specifications

Pinout & Package

SN74ACT138PWRQ1 is supplied in a 16-pin TSSOP (PW) package measuring 5mm × 6.4mm with 0.65mm pitch, featuring wettable flanks for enhanced solder joint inspection. Thermal pad is not present in this variant (only in BQB WQFN).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT138PWRQ1, SN74LV138AQPWRQ1 trades drive strength and speed for wider voltage flexibility and lower static current, while MC74VHC138DT offers identical logic behavior without automotive qualification-making SN74ACT138PWRQ1 the optimal choice for production-grade 5V automotive decoding where robustness and timing precision are critical.

Availability

SN74ACT138PWRQ1 is available at Aetrix Electronics and suitable for automotive body electronics, powertrain control units, and ADAS domain controllers requiring stable component supply with guaranteed long-term manufacturability and AEC-Q100 compliance.

Supply support for SN74ACT138PWRQ1 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 company specializing in analog, embedded processing, and automotive ICs, with over 90 years of innovation in high-reliability electronic components.

The SN74ACT138PWRQ1 belongs to TI's automotive logic portfolio, designed specifically to replace legacy TTL decoders in safety-critical vehicle subsystems while meeting stringent AEC-Q100 reliability and thermal requirements.

FAQ

What is the maximum continuous output current specification for SN74ACT138PWRQ1?

The SN74ACT138PWRQ1 supports ±24mA continuous output current per pin at VCC = 4.5V to 5.5V, verified across the full -40°C to +125°C operating range. This value is specified under IOH = -24mA and IOL = 24mA conditions in the Electrical Characteristics table, and reflects sustained drive capability without thermal derating in typical automotive PCB layouts with adequate copper area.

Does SN74ACT138PWRQ1 support operation at 3.3V supply voltage?

No, SN74ACT138PWRQ1 does not support 3.3V operation. Its recommended operating supply voltage is strictly 4.5V to 5.5V, as defined in Section 5.3 of the datasheet. Attempting to operate below 4.5V may result in undefined logic states, increased propagation delay, or failure to meet VIH/VIL thresholds - it is not characterized or qualified for 3.3V use.

How many enable inputs does SN74ACT138PWRQ1 have, and what are their logic polarities?

SN74ACT138PWRQ1 has three enable inputs: G2 (active-high), G1 (active-low), and G0 (active-low). All three must be simultaneously asserted - i.e., G2 = HIGH, G1 = LOW, G0 = LOW - for normal decoding to occur. If any enable condition is violated, all eight outputs (Y0–Y7) are forced HIGH regardless of A0–A2 address state.

Is SN74ACT138PWRQ1 pin-compatible with standard SN74ACT138 devices?

Yes, SN74ACT138PWRQ1 shares identical pinout, logic function, and DC/AC electrical specifications with commercial-grade SN74ACT138 in TSSOP-16 (PW) package. The "Q1" suffix denotes AEC-Q100 qualification and extended temperature screening - no pin or functional changes are introduced, enabling drop-in replacement in automotive designs requiring enhanced reliability.

What package type is used for SN74ACT138PWRQ1, and does it include a thermal pad?

SN74ACT138PWRQ1 uses the PW (TSSOP-16) package, measuring 5mm × 6.4mm with 0.65mm lead pitch and wettable flanks. It does not include an exposed thermal pad - that feature is exclusive to the BQB (WQFN-16) variant (e.g., SN74ACT138WBQBRQ1). The PW package relies on standard lead-frame conduction for thermal dissipation.