STMicroelectronics LD2982BM50R

Overview

LD2982BM50R from STMicroelectronics is a 50 mA fixed-output low-dropout linear voltage regulator with 1.8 V output, 120 mV dropout at 50 mA, 30 µV_rms output noise, and TTL-compatible inhibit control on Pin 3. It operates from −40 °C to 125 °C and supports stable regulation with only 1 µF ceramic output capacitor - ideal for space-constrained, low-noise battery-powered portable electronics.

For engineers reviewing the LD2982BM50R datasheet, LD2982BM50R pinout, LD2982BM50R application, or LD2982BM50R equivalent, key selection criteria include ultra-low quiescent current (75 µA at 1 mA), sub-1 µA shutdown current, ±1% output tolerance at 25 °C, and SOT23-5L package compatibility with high-density PCB layouts.

Technical Context

The LD2982BM50R integrates a PNP pass transistor enabling ultra-low dropout (7 mV at 1 mA, 120 mV at 50 mA) and inherently blocks reverse current flow between OUT and IN. Its internal feedback network uses implanted resistors (R1 = 42.6 kΩ, R2 = 51.15 kΩ) to set the 1.8 V output with ±1% initial accuracy.

Stability is achieved with low-ESR ceramic capacitors as small as 1 µF (for VO ≥ 3.8 V) or 2.2 µF (for 1.8–3.3 V), aided by a dedicated Bypass pin accepting a 10 nF capacitor to reduce thermal noise to 30 µV_rms. The INHIBIT pin accepts TTL-level logic (V_IL ≤ 0.15 V, V_IH ≥ 2 V) and draws ≤15 µA.

Key Specifications

Pinout & Package

LD2982BM50R is housed in a compact, RoHS-compliant SOT23-5L package (2.8 × 1.6 × 1.3 mm), optimized for automated placement and thermal performance (R_thJA = 255 °C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise, low-I_Q LDO applications.

Compared with TPS7A0518PDBVR and MCP1700T-1802E/TT, the LD2982BM50R uniquely balances ultra-low dropout, integrated noise suppression, and true sub-µA shutdown - making it optimal for compact, battery-critical, noise-sensitive designs where all three attributes are simultaneously required.

Availability

LD2982BM50R is available at Aetrix Electronics and suitable for smartphone baseband power, wearable sensor subsystems, and industrial handheld terminals requiring stable component supply with guaranteed long-term availability.

Supply support for LD2982BM50R 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 silicon solutions for automotive, industrial, and consumer markets since 1987.

The LD2982 belongs to ST's high-precision, low-noise LDO family targeting portable and battery-operated applications where efficiency, size, and signal integrity are co-constrained design priorities.

FAQ

What is the minimum input voltage required for regulation at 1.8 V output?

The LD2982BM50R maintains regulation as long as input voltage exceeds output voltage by its dropout voltage. At 50 mA load, dropout is 120 mV - so minimum VIN is 1.92 V. At 1 mA, dropout drops to 7 mV, allowing regulation down to 1.807 V. This enables operation across the full discharge curve of a single Li-ion cell (3.0–4.2 V) or two alkaline cells (up to 3.2 V).

Can the INHIBIT pin be left unconnected?

No - the INHIBIT pin has no internal pull-up or pull-down and must never be left floating. If shutdown functionality is unused, it must be tied directly to the IN pin to ensure continuous operation. Leaving it open risks undefined state, intermittent shutdown, or increased leakage current due to noise coupling.

Is an external capacitor required on the Bypass pin?

A 10 nF capacitor between Bypass and GND is optional but recommended for noise-sensitive applications. Without it, output noise is ~70 µV_rms; with it, noise drops to 30 µV_rms. The capacitor must be placed adjacent to the pin with short, low-inductance traces - X7R ceramic is preferred for stability across temperature.

Does the LD2982BM50R support reverse current protection?

Yes - the internal PNP pass transistor lacks a parasitic body diode, preventing reverse current flow from OUT to IN when output voltage exceeds input. Reverse current under forced-V_REV conditions is limited to ~160 µA through internal feedback resistors, eliminating need for external blocking diodes in hot-swap or multi-rail systems.