STMicroelectronics LD2979M30TR

Overview

LD2979M30TR from STMicroelectronics is a very low dropout (LDO) linear voltage regulator delivering a fixed 3.0 V output with 50 mA maximum load current, 0.2 V typical dropout at 50 mA, and 500 µA typical quiescent current in active mode. It features TTL-compatible inhibit control, internal current/thermal limiting, and operates across –25 °C to 125 °C for use in battery-powered sensor nodes and portable instrumentation.

For engineers reviewing the LD2979M30TR datasheet, LD2979M30TR pinout, LD2979M30TR application, or LD2979M30TR equivalent, key selection criteria include dropout voltage at 50 mA, shutdown logic threshold (V_IH = 2 V), output noise (160 µV RMS), stability with only 1 µF ceramic output capacitor, and SOT23-5L thermal performance under continuous 50 mA load.

Technical Context

The LD2979M30TR integrates a PNP pass transistor architecture enabling ultra-low dropout operation down to 6 mV at zero load and 400 mV at full 50 mA load. Its inhibit input accepts TTL-level signals without external pull-up, and the device enters true zero-current shutdown when V_INH < 0.18 V.

Stability is achieved with minimal 1 µF ceramic output capacitance due to internal compensation optimized for low-ESR capacitors. Supply voltage rejection remains at 63 dB (typ.) at 120 Hz, supporting clean power delivery in mixed-signal systems where analog sections demand low-noise regulation.

Key Specifications

Pinout & Package

Supplied in the compact, surface-mount SOT23-5L package (3.0 × 1.75 × 1.3 mm), the LD2979M30TR uses five terminals optimized for space-constrained PCB layouts and thermal dissipation in thin-profile applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP2204K-3.0TRG1 and TPS78030DRVR, the LD2979M30TR uniquely balances 50 mA capability, 0.2 V dropout, TTL inhibit, and SOT23-5L compactness-making it optimal for mid-power, dynamically controlled embedded systems where space and battery life are jointly constrained.

Availability

LD2979M30TR is available at Aetrix Electronics and suitable for portable medical sensors, industrial field transmitters, and automotive cabin controllers requiring stable component supply with consistent parametric performance across temperature and load.

Supply support for LD2979M30TR 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, sensors, and analog devices for industrial, automotive, and consumer markets.

The LD2979xx series belongs to ST's precision low-dropout regulator product line, engineered specifically for battery-powered and noise-sensitive applications where minimal voltage overhead and ultra-low quiescent current are critical system requirements.

FAQ

What is the minimum input voltage required for regulation at full 50 mA load?

The LD2979M30TR requires a minimum input voltage of 3.2 V to maintain 3.0 V output at 50 mA load, based on its typical 0.2 V dropout voltage. At worst-case 600 mV dropout (over temperature), input must be ≥3.6 V. Input voltage must not exceed 16 V absolute maximum rating.

Can the NC pin (Pin 4) be connected to ground or left floating?

Pin 4 is internally unconnected and must remain electrically isolated-neither grounded nor driven. ST's mechanical data and pin description explicitly state "Not to be connected." Grounding it may cause unpredictable leakage paths or violate internal isolation boundaries defined in the die layout.

Is an external bypass capacitor required on the inhibit pin?

No external capacitor is required on the INHIBIT pin. The input is TTL-compatible with specified V_IH ≥2 V and V_IL ≤0.18 V, and input current remains below ±1 µA across temperature. Noise immunity is ensured by internal hysteresis; only proper PCB routing (short trace, away from noisy signals) is recommended.

Does the LD2979M30TR support ceramic output capacitors with ESR < 10 mΩ?

Yes-the LD2979M30TR is internally compensated for stability with ceramic capacitors as low as 1 µF and ESR down to 1 mΩ (per test condition in datasheet Figure 12). Unlike older LDOs, it does not require minimum ESR and remains stable with high-quality X7R/X5R ceramics commonly used in space-constrained designs.