STMicroelectronics LD2980ABU33TR

Overview

LD2980ABU33TR from STMicroelectronics is a 3.3 V ultra-low-dropout linear voltage regulator in SOT23-5L package, designed for battery-powered and low-noise systems. It delivers up to 50 mA output current with 120 mV typical dropout at 50 mA, 80 µA typical quiescent current in active mode, and <1 µA shutdown current. Its stable operation with low-ESR ceramic capacitors enables use in cellular phones and portable audio devices.

For engineers reviewing the LD2980ABU33TR datasheet, LD2980ABU33TR pinout, LD2980ABU33TR application, or LD2980ABU33TR equivalent, key selection criteria include dropout voltage at light/heavy load, inhibit logic thresholds (VINH ≤ 0.18 V for OFF), ±0.5% output tolerance (A version), 160 µVRMS output noise, and thermal shutdown at 170 °C.

Technical Context

The LD2980ABU33TR uses a PNP pass transistor architecture enabling ultra-low dropout-just 7 mV typ. at 1 mA and 120 mV typ. at 50 mA-while maintaining stability with 2.2 µF low-ESR ceramic output capacitors. Its inhibit pin (Pin 3) provides TTL-compatible ON/OFF control with defined logic thresholds: VINH ≤ 0.18 V disables output, VINL ≥ 1.3 V enables it.

Internal protection includes current limiting, thermal shutdown at 170 °C, and reverse-current blocking (no body diode between IN and OUT). The device operates across –40 °C to +125 °C junction temperature and achieves 63 dB supply voltage rejection at 1 kHz with 10 µF output capacitance.

Key Specifications

Pinout & Package

SOT23-5L is a 5-pin surface-mount package (2.95 mm × 1.60 mm × 1.30 mm height) with exposed pad for thermal enhancement. Pin 4 is NC (not connected); all pins are accessible on top side only.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LD2980ABU33TR, AP2204K-3.3TRG1 trades ultra-low dropout and shutdown capability for simpler BOM (no enable logic), while MCP1700T-3302E/TT offers higher current capacity at the cost of significantly higher dropout and less aggressive shutdown current-making LD2980ABU33TR optimal for space-constrained, ultra-low-power portable designs.

Availability

LD2980ABU33TR is available at Aetrix Electronics and suitable for cellular phone power management, portable audio DAC supply, and industrial sensor node MCU core applications requiring stable component supply with guaranteed long-term availability.

Supply support for LD2980ABU33TR 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 products for automotive, industrial, and consumer markets since 1987.

The LD2980 series belongs to ST's ultra-low-dropout linear regulator product line, engineered specifically for battery-powered portable electronics demanding sub-100 µA quiescent current and compatibility with miniature ceramic capacitors.

FAQ

What is the minimum input voltage required for stable 3.3 V output at 50 mA load?

The LD2980ABU33TR requires a minimum input voltage of 3.42 V (3.3 V + 120 mV typical dropout) to maintain regulation at 50 mA. At lower loads, dropout drops to 7 mV at 1 mA, allowing operation down to 3.307 V. Input voltage must stay within the absolute maximum rating of 16 V and minimum operating limit of 2.5 V.

Can the INHIBIT pin be left unconnected if shutdown functionality is not needed?

No-the INHIBIT pin is not internally pulled up and must never be left floating. If shutdown is unused, tie Pin 3 directly to VIN to ensure continuous operation. Leaving it open risks undefined behavior, including unintended regulator disable due to noise coupling or leakage paths.

Which output capacitor types and values are validated for stability with LD2980ABU33TR?

ST validates stability with ≥2.2 µF X7R or X5R ceramic capacitors (ESR < 100 mΩ). Tantalum capacitors may work but are not recommended due to size, cost, and ESR drift over temperature. The datasheet specifies 2.2 µF minimum for 3.3 V versions; using smaller values requires adding a series resistor per Figure 18/19 to maintain phase margin.

Does LD2980ABU33TR provide reverse current protection when VOUT exceeds VIN?

Yes-the internal PNP pass transistor lacks an inherent body diode, preventing reverse current flow from VOUT to VIN. When VOUT is forced above VIN, only a small reverse current (~160 µA) flows through internal feedback resistors to GND, eliminating risk of backfeeding upstream supplies or damaging input circuitry.