Texas Instruments SN74LVT125NSR

Overview

SN74LVT125NSR from Texas Instruments is a quad 3-state noninverting buffer designed for mixed-voltage system interfacing, supporting 5-V TTL inputs/outputs with 3.3-V V_CC, operating down to 2.7 V, and featuring bus-hold inputs and I_off for partial-power-down protection. It enables reliable level translation in backplane and motherboard data buses.

For engineers reviewing the SN74LVT125NSR datasheet, SN74LVT125NSR pinout, SN74LVT125NSR application, or SN74LVT125NSR equivalent, key selection considerations include its 3.3-V supply compatibility with 5-V signal environments, bus-hold input retention, I_off current limiting during power-down, and 14-pin SOP-NS package thermal performance (θ_JA = 76°C/W).

Technical Context

The SN74LVT125NSR integrates four independent noninverting buffers, each with an active-low output-enable (OE) control enabling high-impedance state on Y outputs. Its bus-hold circuitry actively maintains logic levels at undriven A inputs without external resistors, reducing BOM count and layout complexity.

Designed for low-voltage operation with robust mixed-mode signaling, it meets JEDEC JESD-17 latch-up immunity (>500 mA) and exceeds JESD22 ESD ratings (2000-V HBM, 200-V MM), while I_off limits reverse current flow when V_CC = 0 V and inputs/outputs are biased to 0–4.5 V.

Key Specifications

Pinout & Package

SOP-NS package: 14-pin small-outline plastic package, 8.75 mm × 3.9 mm body, 1.75 mm max height, 0.65 mm lead pitch, RoHS-compliant NiPdAu finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC125A, SN74LVT125NSR delivers essential 5-V input compatibility and bus-hold for legacy system integration; compared with SN74LVTH125, it offers superior thermal performance in the NS package (76°C/W vs. ≥86°C/W), enabling denser layouts without derating.

Availability

SN74LVT125NSR is available at Aetrix Electronics and suitable for industrial control backplanes, hot-swappable telecom modules, and low-power embedded I/O expansion requiring stable component supply across extended temperature ranges (−40°C to 85°C).

Supply support for SN74LVT125NSR 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 focused on analog and embedded processing technologies, with over 90 years of innovation in high-reliability IC design and manufacturing.

The SN74LVT125NSR belongs to TI's LVT (Low-Voltage BiCMOS Technology) logic family, engineered for mixed-signal interfacing in telecom infrastructure, industrial automation, and computing systems where 3.3-V core logic must reliably communicate with 5-V legacy subsystems.

FAQ

What is the maximum input voltage the SN74LVT125NSR can tolerate on its A pins?

The SN74LVT125NSR supports input voltages up to 5.5 V on its A pins, enabling direct connection to 5-V TTL signal sources while powered from a 3.3-V V_CC. This 5-V tolerance is explicitly specified in the Recommended Operating Conditions table and verified under Absolute Maximum Ratings (VI ≤ 7 V). The device maintains correct logic interpretation (VIH ≥ 2.0 V, VIL ≤ 0.8 V) across its full 2.7–3.6 V supply range, making SN74LVT125NSR ideal for bridging voltage domains without external level shifters.

Does the SN74LVT125NSR require external pullup resistors on its A inputs?

No, the SN74LVT125NSR does not require external pullup resistors on its A inputs because it features integrated bus-hold circuitry. This internal circuit actively maintains the last valid logic state (high or low) at each A input when undriven, with ±75 µA holding current at V_CC = 3 V. Using external resistors with the bus-hold function is explicitly discouraged in the datasheet, as it may interfere with proper state retention. This feature directly reduces BOM count and PCB area in applications like sparse-bus controllers or configuration interfaces where inputs may float during initialization.

How does the I_off feature protect the SN74LVT125NSR during partial power-down?

The I_off feature in the SN74LVT125NSR disables all output drivers and limits leakage current to ±100 µA maximum when V_CC = 0 V and any input or output is biased between 0–4.5 V. This prevents damaging reverse current flow through the device during hot-swap events, staggered power sequencing, or system sleep modes. Unlike standard CMOS buffers, SN74LVT125NSR remains electrically isolated even when other system rails remain active - a critical requirement for telecom line cards and modular industrial controllers where individual sections power up/down independently.

What is the thermal performance of the SN74LVT125NSR in its SOP-NS package?

The SN74LVT125NSR in the SOP-NS package has a junction-to-ambient thermal resistance (θ_JA) of 76°C/W under standard JEDEC test conditions (2-layer board, 1-in² copper pad). This value is lower than competing packages like SOIC-D (86°C/W) or TSSOP-PW (113°C/W), indicating superior heat dissipation capability. At its maximum recommended I_OL of 64 mA and typical V_OL of 0.5 V, power dissipation per buffer is ~32 mW - resulting in a worst-case junction temperature rise of just 2.4°C above ambient. This makes SN74LVT125NSR well-suited for compact, thermally constrained layouts in dense backplane or module designs.

Can the SN74LVT125NSR be used in automotive applications?

The standard SN74LVT125NSR is not qualified for automotive use; however, Texas Instruments offers the pin-compatible SN74LVT125-Q1 variant, which is AEC-Q100 Grade 2 qualified (−40°C to +105°C) and tested for zero-defect reliability in automotive control modules. The SN74LVT125NSR itself is rated for −40°C to +85°C and intended for industrial, telecom, and computing applications. For automotive deployment, designers must specify SN74LVT125-Q1 - not SN74LVT125NSR - to meet functional safety and qualification requirements such as ISO/TS 16949 and AEC-Q100 stress testing protocols.