STMicroelectronics LM2931ADT33RY

Overview

LM2931ADT33RY from STMicroelectronics is a fixed-output 3.3 V, 100 mA low-dropout linear regulator in SO-8 package with inhibit control, AEC-Q100 qualified, 90 mV typical dropout at 10 mA, and load dump protection up to 60 V - designed for automotive body control modules requiring stable local regulation under harsh transients.

For engineers reviewing the LM2931ADT33RY datasheet, LM2931ADT33RY pinout, LM2931ADT33RY application, or LM2931ADT33RY equivalent, key selection criteria include dropout voltage at light/heavy load, inhibit logic thresholds (VIL = 1.2 V, VIH = 3.25 V), reverse transient tolerance (–50 V), thermal resistance (RthJA = 55 °C/W), and SO-8 compatibility with legacy L78L footprints.

Technical Context

The LM2931ADT33RY implements a PNP-based LDO architecture with internal current and thermal limiting, enabling safe operation during sustained overload or high ambient temperature (up to 125 °C junction). Its inhibit input (PIN 1) provides TTL-compatible shutdown control: device enables when VINH < 1.2 V and disables when VINH > 3.25 V.

It features integrated protection against reverse battery connection (–15 V continuous, –50 V transient), 60 V load dump survival via automatic shutdown, and output noise of 330 µVRMS (10 Hz–100 kHz), making it suitable for noise-sensitive analog subsystems in automotive ECUs.

Key Specifications

Pinout & Package

LM2931ADT33RY uses the SO-8 surface-mount package (ECOPACK® compliant), with 1.27 mm pitch, 5.0 × 6.2 mm body, and exposed pad for thermal enhancement. Pin 1 is INH (inhibit control), Pin 2 is GND, Pin 3 is VIN, Pin 4 is GND, Pin 5 is VOUT, Pin 6 is GND, Pin 7 is VOUT, Pin 8 is GND - dual VOUT/GND pins reduce IR drop and improve PSRR.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout regulator applications.

Compared with TLV73333PDBVR and TPS7B6733QPWPRQ1, the LM2931ADT33RY uniquely combines AEC-Q100 qualification, integrated 60 V load dump survival, –50 V reverse transient tolerance, and TTL-compatible inhibit - making it the only single-chip solution for cost-sensitive, space-constrained automotive LDO applications requiring full battery-direct robustness and power gating.

Availability

LM2931ADT33RY is available at Aetrix Electronics and suitable for automotive body electronics, telematics gateways, and ADAS camera ECUs requiring stable component supply across extended temperature and transient conditions.

Supply support for LM2931ADT33RY 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing silicon solutions for automotive, industrial, and consumer markets since 1987.

The LM2931 series belongs to ST's automotive-grade linear regulator product line, engineered specifically for robust local power management in battery-connected vehicle subsystems where reliability under electrical stress is non-negotiable.

FAQ

What is the maximum allowable input voltage for continuous operation?

The LM2931ADT33RY supports continuous DC input voltages from 6 V to 26 V. Exceeding 26 V risks permanent damage unless limited to ≤100 ms duration and ≤60 V amplitude, per its transient rating. Operation outside this range voids AEC-Q100 compliance and may trigger internal shutdown.

Does the SO-8 package require an external capacitor on the inhibit pin?

No external capacitor is required on the INH pin. The inhibit input has internal hysteresis and draws only 22–50 µA at 2.5 V; it is designed for direct connection to GPIO or open-collector drivers. Adding capacitance may slow enable/disable timing beyond datasheet-specified limits.

Can LM2931ADT33RY replace LM78L33 in existing SO-8 designs?

Yes - LM2931ADT33RY is pin-compatible with LM78L33 in SO-8 footprint and provides identical 3.3 V output, but adds inhibit control, lower dropout (90 mV vs ~1.7 V), and automotive-grade protection. No layout changes are needed; only firmware update for INH control is required to leverage new features.

How does thermal performance compare between SO-8 and DPAK packages?

SO-8 has RthJA = 55 °C/W (with 6 cm² copper), while DPAK achieves 100 °C/W - meaning SO-8 delivers ~1.8× better thermal efficiency at same board area. For 100 mA load at 85 °C ambient, SO-8 maintains safe junction temperature; DPAK requires larger copper or forced air to match.