STMicroelectronics LD2982AM35R

Overview

LD2982AM35R from STMicroelectronics is a 50 mA fixed-output low-dropout linear voltage regulator with 1.8 V nominal output, ultra-low dropout (120 mV @ 50 mA), 30 µV_RMS output noise, and logic-controlled inhibit function. It operates from 2.5 V to 16 V input, supports −40 °C to +125 °C junction temperature, and uses only a 1 µF ceramic output capacitor for stability - ideal for space-constrained, battery-powered portable electronics requiring clean, low-power bias rails.

For engineers reviewing the LD2982AM35R datasheet, LD2982AM35R pinout, LD2982AM35R application, or LD2982AM35R equivalent, key selection criteria include dropout performance at light load, sub-1 µA shutdown current, bypass-capacitor–enabled noise reduction, and SOT23-5L footprint compatibility in high-density PCB layouts.

Technical Context

The LD2982AM35R integrates a PNP pass transistor enabling ultra-low dropout operation, with internal current and thermal limiting. Its inhibit pin (Pin 3) accepts TTL-compatible logic levels (V_IL ≤ 0.15 V, V_IH ≥ 2 V) to disable regulation and reduce quiescent current to <1 µA - critical for system-level power gating.

Output noise is actively suppressed via an external 10 nF bypass capacitor on Pin 4, reducing RMS noise to 30 µV (300 Hz–50 kHz). Supply voltage rejection remains ≥45 dB at 1 kHz, and stability is guaranteed with low-ESR ceramic capacitors as small as 1 µF for 1.8 V output.

Key Specifications

Pinout & Package

SOT23-5L package: 5-pin surface-mount, 1.45 mm height, lead-free and RoHS-compliant per ECOPACK® specifications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6219B182MR-G and MIC5205-1.8YM5, LD2982AM35R uniquely combines sub-1 µA shutdown, dedicated bypass pin for 30 µV_RMS noise, and SOT23-5L footprint - making it optimal for compact, battery-critical, noise-sensitive applications where dynamic power control is mandatory.

Availability

LD2982AM35R is available at Aetrix Electronics and suitable for portable audio devices, wearable health sensors, industrial IoT edge nodes, and medical patch monitors requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for LD2982AM35R 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 belongs to ST's high-performance LDO family targeting ultra-low-noise, ultra-low-power portable and medical applications - engineered specifically for battery longevity, signal integrity, and minimal PCB area.

FAQ

What is the minimum input voltage required for LD2982AM35R to maintain 1.8 V output at 50 mA?

The dropout voltage is 120 mV at 50 mA load, so the minimum input voltage is 1.8 V + 0.12 V = 1.92 V. This enables reliable operation down to the final discharge voltage of single-cell Li-ion or alkaline batteries, preserving usable runtime in portable systems.

Can LD2982AM35R be used without the bypass capacitor?

Yes - the device functions without the 10 nF bypass capacitor on Pin 4, but output noise increases from 30 µV_RMS to over 100 µV_RMS. The bypass cap is optional for noise-critical analog rails (e.g., ADC references) but may be omitted in digital-only applications where noise immunity is less stringent.

Is the INHIBIT pin internally pulled up or pulled down?

No - the INHIBIT pin has no internal pull-up or pull-down. It must be actively driven: tied to VIN to enable regulation, or pulled below 0.15 V (e.g., via MCU GPIO) to disable. Leaving it floating risks undefined behavior and potential oscillation or partial turn-on.

What is the maximum allowable output capacitance for LD2982AM35R?

There is no upper limit on output capacitance - larger values improve transient response and reduce output impedance. However, ST recommends ≥1 µF ceramic for 1.8 V versions. Capacitances up to 100 µF are commonly used; ensure ESR remains low (<1 Ω) and capacitor voltage rating exceeds 2.5 V.