STMicroelectronics LM2931AD50R

Overview

LM2931AD50R from STMicroelectronics is a fixed 5.0 V, 100 mA low-dropout linear regulator in DPAK package, featuring 90 mV typical dropout at 10 mA, 2.5 mA quiescent current at full load, and AEC-Q100 qualification for automotive use. It integrates load dump protection up to 60 V, reverse transient protection to –50 V, and thermal/current limiting - deployed as a local power rail in engine control units, body electronics, and infotainment power domains.

For engineers reviewing the LM2931AD50R datasheet, LM2931AD50R pinout, LM2931AD50R application, or LM2931AD50R equivalent, key selection criteria include dropout voltage under 100 mA load, shutdown logic compatibility with L78L-family footprints, thermal resistance (R_thJC = 8 °C/W), and transient survivability during battery jump-starts or load dumps.

Technical Context

The LM2931AD50R implements a PNP-based pass transistor architecture enabling ultra-low dropout operation, with internal feedback loop compensation optimized for stability with 100 µF output capacitance. Its inhibit input (VINH) enables digital enable/disable control: regulator activates when VINH < 1.2 V and shuts down when VINH > 3.25 V, reducing system standby power.

Protection circuitry includes foldback current limiting, thermal shutdown at ~160 °C junction temperature, and robust ESD-hardened input stage rated for ±50 V reverse transients (100 ms). The device operates across –40 to +125 °C ambient, meeting automotive-grade reliability requirements without external components beyond input/output capacitors.

Key Specifications

Pinout & Package

DPAK package (TO-252-3) with exposed thermal pad; thermally enhanced for automotive under-hood environments. Pin 1 = VOUT, Pin 2 = GND, Pin 3 = VIN - compatible with standard DPAK footprint per DS1760 Rev 24 Figure 23.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 5 V automotive LDO applications.

Compared with TLV73350PDBVR and TPS7B6950QDCYRQ1, the LM2931AD50R uniquely balances AEC-Q100 compliance, DPAK thermal performance (8 °C/W), and integrated 60 V/–50 V transient hardening - making it optimal for cost-constrained, space-limited under-hood regulators where external protection is prohibitive.

Availability

LM2931AD50R is available at Aetrix Electronics and suitable for automotive engine control units, body control modules, and infotainment systems requiring stable component supply across extended temperature and transient stress conditions.

Supply support for LM2931AD50R 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 since 1987.

The LM2931 series belongs to ST's automotive-qualified linear regulator product line, engineered specifically for robustness in 12 V vehicle electrical systems - emphasizing transient immunity, thermal resilience, and seamless integration into legacy L78L-compatible designs.

FAQ

What is the maximum allowable input voltage for continuous operation?

The LM2931AD50R supports continuous DC input up to 26 V across its full operating temperature range (–40 to +125 °C). Exceeding this voltage triggers automatic shutdown during transients (e.g., 60 V load dump), but sustained operation above 26 V risks permanent damage per Absolute Maximum Ratings Table 1.

Does the DPAK package require soldering the thermal pad to PCB ground?

Yes - the exposed thermal pad on the DPAK package (Pin 2/GND) must be soldered to a minimum 6 cm² copper pour connected to system ground. This achieves the specified R_thJA = 100 °C/W and enables full 100 mA output capability; omitting the pad increases junction temperature by >40 °C at rated load.

Can the inhibit pin be left floating in always-on applications?

No - the inhibit pin (VINH) must be actively pulled to GND (≤1.2 V) to enable regulation. A floating VINH may settle near threshold voltage, causing erratic enable/disable behavior or increased quiescent current. For always-on use, tie VINH directly to GND with a low-impedance connection.

Is an input capacitor required for stability?

Yes - a minimum 0.1 µF ceramic capacitor (X7R, 10 V rating) is required between VIN and GND, placed within 5 mm of the device pins. This suppresses high-frequency noise and prevents oscillation during fast load transients, as validated in Figure 21 (Line Transient) and stability analysis in Figure 20.