STMicroelectronics LD2982AM33R

Overview

LD2982AM33R from STMicroelectronics is a 50 mA fixed-output low-dropout (LDO) linear voltage regulator with logic-controlled inhibit function, delivering 3.3 V output at ±1% tolerance (25 °C), 120 mV dropout at 50 mA load, and 30 µV_RMS output noise with 10 nF bypass capacitor. It operates across –40 °C to +125 °C and supports battery-powered portable electronics requiring ultra-low quiescent current and high PSRR.

For engineers reviewing the LD2982AM33R datasheet, LD2982AM33R pinout, LD2982AM33R application, or LD2982AM33R equivalent, key selection criteria include its TTL-compatible INHIBIT control, 1 µF minimum ceramic output capacitor requirement, <1 µA shutdown current, and SOT23-5L package compatibility with space-constrained PCB layouts.

Technical Context

The LD2982AM33R integrates a PNP pass transistor enabling ultra-low dropout operation-just 7 mV at 1 mA and 120 mV at 50 mA-while maintaining stable regulation under varying input voltage (2.5 V to 16 V) and load conditions. Its internal feedback network ensures precise 3.3 V output with ±1% initial accuracy and <±2.6% total variation over temperature (–40 °C to +125 °C).

It features dual-stage noise suppression: a dedicated Bypass pin accepts a 10 nF capacitor to reduce output noise to 30 µV_RMS (300 Hz–50 kHz), and achieves 45 dB supply voltage rejection at 1 kHz. The INHIBIT pin (Pin 3) provides TTL-compatible enable/disable control with logic-low threshold ≤0.15 V and leakage <15 µA.

Key Specifications

Pinout & Package

SOT23-5L package: 5-pin surface-mount, 1.3 mm height, 2.8 × 1.75 mm footprint, ECOPACK® compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP2210K-3.3TRG1 and MCP1703T-3302E/MB, the LD2982AM33R uniquely combines sub-µA shutdown, Bypass-enabled 30 µV_RMS noise, and 120 mV dropout in SOT23-5L-making it optimal for space-constrained, battery-operated systems demanding both ultra-low power and ultra-clean power.

Availability

LD2982AM33R is available at Aetrix Electronics and suitable for portable medical sensors, wearable health monitors, industrial IoT edge nodes, and automotive cabin controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LD2982AM33R 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, analog chips, and MEMS sensors for industrial, automotive, and consumer markets.

The LD2982 series belongs to ST's precision low-noise LDO portfolio, engineered specifically for battery-powered portable electronics where ultra-low dropout, sub-µA shutdown, and clean output voltage are critical design requirements.

FAQ

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

The LD2982AM33R requires a minimum input voltage of 3.42 V to maintain regulation at 50 mA load, based on its 120 mV typical dropout voltage. At lighter loads (e.g., 1 mA), input can drop to 3.307 V due to 7 mV dropout. Input below 2.5 V is outside absolute maximum ratings and will disable regulation.

Can the INHIBIT pin be left unconnected?

No-the INHIBIT pin must never be left floating. If shutdown functionality is unused, it must be tied directly to the IN pin to ensure continuous operation. Floating the pin risks undefined behavior, including intermittent output disable or increased leakage current, as the internal circuit lacks pull-up/pull-down.

Why is a 10 nF capacitor required on the Bypass pin?

The 10 nF capacitor on the Bypass pin shunts high-frequency noise from the internal reference amplifier, reducing integrated output noise from ~100 µV_RMS to 30 µV_RMS (300 Hz–50 kHz). This is essential for powering noise-sensitive analog blocks like ADCs or RF synthesizers where supply-induced jitter degrades performance.

Is the LD2982AM33R compatible with ceramic output capacitors below 2.2 µF?

ST specifies 2.2 µF as the minimum ceramic output capacitance for 3.3 V versions to guarantee stability across temperature and process variation. Using <2.2 µF risks oscillation unless a series resistor (typically 1–5 Ω) is added to raise ESR into the stable zone-verified per Figure 5 and Section 6.3 of the datasheet.