Texas Instruments SN74LVC2G126DCTR

Overview

SN74LVC2G126DCTR from Texas Instruments is a dual 3-state bus buffer gate designed for level translation and signal isolation in low-voltage digital systems. It operates from 1.65 V to 5.5 V, supports 5.5-V-tolerant inputs, delivers ±24 mA output drive at 3.3 V, achieves 4 ns max propagation delay, and features Ioff for live insertion in partial-power-down applications - used in high-speed data acquisition and video infrastructure interfaces.

For engineers reviewing the SN74LVC2G126DCTR datasheet, SN74LVC2G126DCTR pinout, SN74LVC2G126DCTR application, or SN74LVC2G126DCTR equivalent, key selection criteria include 3-state control timing (ten/tdis), 5.5-V input tolerance enabling 5 V-to-3.3 V down translation, thermal resistance (220°C/W for DCT package), Ioff leakage specification (<10 µA), and compatibility with NanoFree™ SM8 packaging for space-constrained PCB layouts.

Technical Context

The SN74LVC2G126DCTR implements two independent noninverting buffers, each with dedicated active-low 3-state enable (1OE, 2OE). Its CMOS design supports bidirectional voltage translation: inputs tolerate up to 5.5 V regardless of VCC (1.65–5.5 V), allowing interfacing between 5-V legacy logic and 3.3-V or 1.8-V domains. The Ioff circuit actively disables outputs when VCC = 0 V, blocking back-drive current and enabling hot-plug capability.

Switching performance is characterized across temperature (–40°C to +125°C) and supply voltage (1.8 V to 5 V); tpd ranges from 1.0 ns (5 V) to 5.0 ns (1.8 V) at max operating temperature. Output ground bounce (VOLP < 0.8 V) and undershoot (VOHV > 2 V) are specified at 3.3 V/25°C, confirming robust signal integrity in fast-switching environments.

Key Specifications

Pinout & Package

SN74LVC2G126DCTR uses the SM8 (Small Outline Package, 8-pin) with 2.95 mm × 2.80 mm body size and 0.65 mm lead pitch. It is RoHS-compliant, lead-finished with Sn, and rated MSL Level-1 (unlimited floor life at ≤30°C/60% RH).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual 3-state buffer applications.

Compared with SN74LVC2G126DCTR, SN74LVC2G125DCTR changes signal polarity - requiring redesign of downstream logic - while 74LVC2G126GW,115 offers functional equivalence but demands PCB footprint revision due to larger TSSOP8 dimensions and distinct pin alignment.

Availability

SN74LVC2G126DCTR is available at Aetrix Electronics and suitable for cable modem termination systems, high-speed data acquisition, and military radar signal processing requiring stable component supply across extended temperature and long-lifecycle programs.

Supply support for SN74LVC2G126DCTR 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 connectivity technologies with over 50 years of innovation in high-reliability logic and interface solutions.

The SN74LVC2G126 series belongs to TI's LVC (Low-Voltage CMOS) logic family, engineered for low-power, high-speed voltage translation and bus isolation in space-constrained, mixed-supply digital systems.

FAQ

What is the maximum input voltage the SN74LVC2G126DCTR can tolerate?

The SN74LVC2G126DCTR accepts input voltages up to 5.5 V regardless of VCC level - a key feature enabling direct interfacing with 5-V logic while operating from 1.65–5.5 V supplies. This eliminates external level shifters in mixed-voltage systems. The absolute maximum rating for VI is 6.5 V, but sustained operation above 5.5 V violates recommended conditions and risks reliability degradation. Always reference Section 6.1 and 6.3 of the official datasheet for safe operating margins.

Does the SN74LVC2G126DCTR support hot-plug or live-insertion applications?

Yes, the SN74LVC2G126DCTR supports live insertion via its Ioff feature: when VCC = 0 V, leakage current remains below 10 µA even with 5.5 V applied to inputs or outputs. This prevents damaging back-current flow during partial-power-down or hot-swap events. To ensure robust behavior, tie OE pins to VCC through a pulldown resistor during power-up. This functionality is explicitly validated per JESD78 Class II latch-up testing and documented in Section 8.3 of the datasheet.

What is the thermal resistance (θJA) of the SN74LVC2G126DCTR in its SM8 package?

The SN74LVC2G126DCTR in the DCT (SM8) package has a junction-to-ambient thermal resistance (θJA) of 220°C/W under standard JEDEC PCB conditions. This value assumes a 2-layer board with 1-in² copper pour and is critical for estimating junction temperature rise under load. For example, at 10 mA ICC and 3.3 V, power dissipation is ~33 mW - resulting in ~7.3°C rise above ambient. Thermal derating is required above 85°C ambient per Section 6.4 of the datasheet.

Can the SN74LVC2G126DCTR be used for voltage level translation?

Yes, the SN74LVC2G126DCTR functions as a unidirectional down-translator: it accepts 5-V inputs while powered from 3.3 V or 1.8 V, producing valid CMOS output levels referenced to VCC. For instance, with VCC = 1.8 V, a 5-V input yields a 1.8-V output swing. It does not support bidirectional translation or up-translation (e.g., 1.8 V → 5 V). This capability is confirmed in Section 8.3 Feature Description and Figure 9-1 Typical Application schematic.

What is the recommended bypass capacitor for the SN74LVC2G126DCTR VCC pin?

Texas Instruments recommends a 0.1-µF ceramic bypass capacitor placed as close as possible to the VCC pin of the SN74LVC2G126DCTR, with low-inductance connection to GND. This mitigates supply noise generated during fast output transitions (e.g., 24 mA switching in <4 ns). For boards with multiple logic devices, paralleling a 0.01-µF capacitor may improve high-frequency decoupling. Layout guidance is detailed in Section 10 and Figure 11-1 of the datasheet.