Texas Instruments LM2931T-5.0

Overview

LM2931T-5.0 from Texas Instruments is a fixed-output 5.0 V, low-dropout linear regulator in TO-220-3 package, delivering ≥100 mA output current with ≤0.6 V input-output differential at 100 mA and reverse battery protection up to −50 V. It targets automotive memory standby and low-power processor supplies where quiescent current ≤1.0 mA at 10 mA load is critical.

For engineers reviewing the LM2931T-5.0 datasheet, LM2931T-5.0 pinout, LM2931T-5.0 application, or LM2931T-5.0 equivalent, key selection criteria include dropout voltage at full load, load dump immunity (60 V), thermal shutdown behavior, and compatibility with 100 μF output capacitor for stability under transients.

Technical Context

The LM2931T-5.0 integrates internal thermal overload and short-circuit protection, operates across −40°C to +85°C ambient, and features mirror-image insertion tolerance. Its regulation loop maintains 5.0 V ±3.8% (A grade) over 6–26 V input and 5–100 mA load, with ripple rejection ≥80 dB at 120 Hz.

Designed for automotive environments, it withstands 60 V load dump transients and −50 V reverse-battery transients without damage. The device requires no external components for basic operation but mandates a minimum 100 μF output capacitor with appropriate ESR for stability across temperature and load extremes.

Key Specifications

Pinout & Package

LM2931T-5.0 uses the TO-220-3 package (NDE outline), with tab electrically connected to Pin 2 (Ground). Thermal resistance θ_JA = 50°C/W without heatsink; mounting to PCB copper improves dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2931AS-5.0/NOPB, LM2931T-5.0 offers superior thermal performance in through-hole applications and simpler heatsinking; compared with TLV73350PDBVR, it provides automotive-grade transient robustness at the expense of higher quiescent current and larger footprint.

Availability

LM2931T-5.0 is available at Aetrix Electronics and suitable for automotive electronic control units, industrial sensor nodes, and legacy microprocessor power supplies requiring stable component supply with long lifecycle support.

Supply support for LM2931T-5.0 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 company headquartered in Dallas, Texas, specializing in analog and embedded processing technologies with broad automotive, industrial, and personal electronics reach.

The LM2931-N series was designed specifically for automotive standby power systems, emphasizing reverse-battery resilience, load dump survival, and ultra-low quiescent current in harsh environments.

FAQ

What is the maximum input voltage for LM2931T-5.0 under normal operating conditions?

The LM2931T-5.0 has a maximum operational input voltage of 26 V under continuous DC conditions. It also withstands transient overvoltages up to 60 V (load dump) and reverse transients down to −50 V, as specified in the absolute maximum ratings table of the TI SNOSBE5G datasheet. These limits apply regardless of duration or duty cycle, and the device automatically shuts down during overvoltage events to protect itself and downstream circuitry. LM2931T-5.0 remains fully functional after such events without parameter degradation.

Does LM2931T-5.0 require an external output capacitor, and what value is recommended?

Yes, LM2931T-5.0 requires an external output capacitor for stability. Texas Instruments specifies a minimum of 100 μF aluminum electrolytic capacitor with appropriate ESR, placed as close as possible to the output pin. Lower values may suffice for reduced load currents or elevated temperatures, but 100 μF is the baseline for full 100 mA operation across −40°C to +85°C. Using a capacitor rated for the same temperature range and verifying stability via bench testing at worst-case conditions is mandatory. LM2931T-5.0 will oscillate without proper output capacitance.

What is the dropout voltage specification for LM2931T-5.0 at 100 mA output current?

The dropout voltage for LM2931T-5.0 is specified as ≤0.6 V maximum at 100 mA output current and TJ = 25°C, per the "ELECTRICAL CHARACTERISTICS FOR FIXED 5V VERSION" table in the SNOSBE5G datasheet. This means the device maintains regulation as long as the input voltage remains ≥5.6 V. Dropout increases slightly at higher junction temperatures and lower input voltages, but the 0.6 V limit ensures reliable operation in battery-powered systems nearing end-of-life. LM2931T-5.0 delivers its full rated output within this constraint.

Is LM2931T-5.0 pin-compatible with other regulators in the LM2931-N family?

No - LM2931T-5.0 (TO-220-3) is not pin-compatible with adjustable versions (e.g., LM2931CT-5.0, which has 5 pins) or SOIC-8 variants (e.g., LM2931AM-5.0). The TO-220-3 package has Input–Ground–Output pinout, while the 5-pin TO-220 includes ON/OFF and Sense pins. Substituting packages without verifying pin mapping and circuit modifications will cause functional failure. LM2931T-5.0 shares electrical behavior with other fixed 5 V members but requires mechanical and layout validation for each package variant.

What thermal considerations apply when using LM2931T-5.0 without a heatsink?

Without a heatsink, LM2931T-5.0 in TO-220-3 has θ_JA = 50°C/W. At 100 mA output with 12 V input, power dissipation is ~0.7 W, causing ~35°C rise above ambient - acceptable up to +50°C ambient. Above that, junction temperature exceeds 125°C, triggering thermal shutdown. For continuous 100 mA operation at +85°C ambient, a heatsink reducing θ_JA to ≤20°C/W is required. LM2931T-5.0's metal tab must be electrically isolated from chassis ground unless connected to Pin 2 (Ground).