STMicroelectronics LM2931ADT50R

Overview

LM2931ADT50R from STMicroelectronics is a fixed 5.0 V, 100 mA low-dropout linear regulator in SO-8 package with inhibit control, designed for automotive and industrial local power regulation. It delivers 90 mV typical dropout at 10 mA, 2.5 mA quiescent current at 100 mA load, and withstands 60 V load dump transients-enabling robust operation in 12 V battery systems.

For engineers reviewing the LM2931ADT50R datasheet, LM2931ADT50R pinout, LM2931ADT50R application, or LM2931ADT50R equivalent, key selection criteria include its AEC-Q100 qualification (DPAK variant), shutdown logic interface (VINH), reverse polarity protection to −50 V, and thermal/overcurrent internal limiting-critical for automotive ECU, body control modules, and infotainment subsystems.

Technical Context

The LM2931ADT50R implements a PNP-based LDO architecture with integrated inhibit logic: regulator enables when VINH < 1.2 V and disables when VINH > 3.25 V. Its internal current and thermal limits operate autonomously without external components.

It features load-dump protection up to 60 V (t < 100 ms) and reverse transient tolerance to −50 V, with output voltage stability maintained across −40 °C to +125 °C junction temperature. The SO-8 package supports compatibility with legacy L78L footprint while adding active shutdown capability.

Key Specifications

Pinout & Package

LM2931ADT50R is housed in a standard SO-8 surface-mount package (ECOPACK® compliant), with exposed pad for thermal enhancement. Pin 1 = VOUT, Pin 2 = GND, Pin 3 = VIN, Pin 4 = INH (inhibit control input), Pins 5–8 = GND (multiple ground connections for low-impedance return path).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output LDO regulator applications.

Compared with LM2931CDT50R, the LM2931ADT50R adds AEC-Q100 qualification and extended thermal robustness; versus TLD1114-1EP, it trades diagnostic features and lower dropout for lower cost, simpler integration, and proven field reliability in non-ASIL applications.

Availability

LM2931ADT50R is available at Aetrix Electronics and suitable for automotive electronic control units, telematics systems, and industrial sensor nodes requiring stable component supply under extended temperature and transient stress conditions.

Supply support for LM2931ADT50R 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 microcontrollers, power management ICs, and automotive-grade analog devices.

The LM2931 series belongs to ST's automotive-qualified linear regulator product line, engineered specifically for fault-tolerant, low-power local regulation in 12 V/24 V vehicle electrical architectures.

FAQ

What is the maximum allowable input voltage for continuous operation?

The LM2931ADT50R supports continuous DC input voltages from 6 V to 26 V. Exceeding 26 V risks permanent damage unless limited to ≤60 V for durations under 100 ms, during which internal protection activates. Operation outside this range voids warranty and may degrade long-term reliability.

Does the INH pin require a pull-down resistor for default-enable operation?

No external pull-down is required. When left unconnected, the INH pin's internal leakage keeps voltage below 1.2 V, enabling the regulator by default. A 10 kΩ pull-down may be added for deterministic startup in noisy environments, but is not mandatory per datasheet Figure 3.

Can LM2931ADT50R replace LM78L05 in existing SO-8 designs?

Yes-pinout and footprint are fully compatible with the legacy L78L family. However, LM2931ADT50R offers significantly lower dropout (90 mV vs ~1.7 V), higher transient immunity (60 V vs 35 V), and inhibit control-requiring only minor schematic updates to leverage new features.

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

In SO-8, R_thJA is 55 °C/W (with 6 cm² copper heatsink); in DPAK, it is 100 °C/W. DPAK offers superior power dissipation capability due to lower R_thJC (8 °C/W vs 20 °C/W), making it preferred for sustained 100 mA loads above 85 °C ambient-SO-8 remains optimal for space-constrained, lower-power automotive modules.