STMicroelectronics LM2931BZ50

Overview

LM2931BZ50 from STMicroelectronics is a fixed 5.0 V, very low-dropout linear regulator in TO-92 package, designed for automotive and industrial power management. It delivers up to 100 mA output current with 90 mV typical dropout at 10 mA, 2.5 mA quiescent current at full load, and operates across –40 °C to +125 °C. Its reverse transient protection (–50 V), load dump tolerance (60 V), and internal thermal/current limiting make it suitable for battery-powered ECUs and body control modules.

For engineers reviewing the LM2931BZ50 datasheet, LM2931BZ50 pinout, LM2931BZ50 application, or LM2931BZ50 equivalent, key selection considerations include its AEC-Q100 qualification (DPAK only), TO-92 mechanical compatibility with legacy L78L footprints, fixed 5 V output accuracy (±2.5% over temperature), and shutdown-capable SO-8 variant availability for system-level power sequencing.

Technical Context

The LM2931BZ50 implements a PNP-based pass transistor architecture enabling ultra-low dropout operation - output remains regulated even when input falls within 90 mV of V_OUT. Its internal bandgap reference and error amplifier maintain tight output regulation under line (±4 mV over VI = 6–26 V) and load (±33 mV over IO = 5–100 mA) variations.

Protection circuitry includes active shutdown during transients exceeding 60 V (load dump) or –50 V (reverse battery), plus thermal foldback and current limiting that clamp short-circuit current between 100 mA and 300 mA. The TO-92 variant lacks inhibit control; shutdown functionality is exclusive to SO-8 packaging.

Key Specifications

Pinout & Package

LM2931BZ50 uses the standard TO-92 through-hole package (mechanical dimensions per DS1760 Rev 24 Table 8), with 3 terminals arranged in bottom-view orientation. Thermal resistance is R_thJA = 200 °C/W on standard PCB layout.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2931BZ50, the DPAK LM2931AD50R adds AEC-Q100 validation and better thermal performance but requires PCB redesign; the TLV73350PDBVR reduces board space and quiescent draw but forfeits automotive-grade surge resilience entirely.

Availability

LM2931BZ50 is available at Aetrix Electronics and suitable for engine control units, body control modules, telematics systems, and ADAS camera modules requiring stable component supply across extended temperature ranges and harsh electrical environments.

Supply support for LM2931BZ50 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, specializing in automotive, industrial, and power management ICs with vertical manufacturing capability.

The LM2931 series belongs to ST's automotive-qualified linear regulator product line, engineered specifically for robustness in vehicle electrical systems exposed to load dump, reverse battery, and wide ambient temperature swings.

FAQ

What is the maximum input voltage the LM2931BZ50 can withstand during transient events?

The LM2931BZ50 tolerates up to +60 V for ≤100 ms (load dump) and –50 V for ≤100 ms (reverse polarity), per Absolute Maximum Ratings Table 1. These ratings are enforced by internal protection circuitry that temporarily shuts down regulation without damage - no external TVS diode is required for basic compliance.

Does the LM2931BZ50 support enable/shutdown control?

No. The TO-92 packaged LM2931BZ50 has no inhibit pin; shutdown functionality is only available on the SO-8 variant (e.g., LM2931AD50R). This part operates continuously when powered within its input voltage range and does not support logic-controlled power gating.

What output capacitor value is required for stability?

A minimum 100 µF aluminum or tantalum output capacitor is required for stability, as specified in Figure 3 (Application Circuit for Fixed Output) and confirmed in Figure 20 (Stability vs C_O). Ceramic capacitors alone are insufficient; ESR ≥ 0.1 Ω is recommended to ensure phase margin.

How does the LM2931BZ50 compare to standard 78L05 regulators in automotive use?

Unlike legacy 78L05 devices, the LM2931BZ50 features 90 mV dropout (vs. ~1.7 V), 60 V load dump immunity (vs. none), and –50 V reverse polarity survival (vs. immediate destruction). It maintains regulation during cranking and survives jump-start errors - making it a drop-in upgrade for automotive 5 V rails without redesigning protection circuitry.