STMicroelectronics LD2982BM35R

Overview

LD2982BM35R from STMicroelectronics is a 50 mA fixed-output low-dropout (LDO) voltage regulator with 1.8 V output, 120 mV dropout at 50 mA, 30 µV_RMS output noise, logic-controlled inhibit function, and SOT23-5L package. It delivers ultra-low quiescent current (75 µA at 1 mA load), operates from −40 °C to 125 °C, and supports battery-powered portable electronics requiring stable, low-noise local regulation.

For engineers reviewing the LD2982BM35R datasheet, LD2982BM35R pinout, LD2982BM35R application, or LD2982BM35R equivalent, key selection criteria include dropout performance under light/heavy load, inhibit logic threshold compatibility (V_IL = 0.15 V), bypass capacitor noise reduction (10 nF to GND), and ±1% output tolerance at 25 °C for precision rail generation.

Technical Context

The LD2982BM35R uses a PNP pass transistor architecture enabling very low dropout voltage-just 7 mV at 1 mA and 120 mV at 50 mA-while maintaining stability with only 1 µF ceramic output capacitance. Its internal feedback network sets a precise 1.8 V output with ±1% initial accuracy and <±0.1 V drift over −40 °C to 125 °C.

Inhibit control is implemented on Pin 3 (INHIBIT) with TTL-compatible thresholds: device disables when pulled below 0.18 V, drawing <1 µA quiescent current; no internal pull-up requires external biasing. The Bypass pin (Pin 4) accepts a 10 nF capacitor to ground to reduce thermal noise to 30 µV_RMS (300 Hz–50 kHz).

Key Specifications

Pinout & Package

LD2982BM35R is housed in a compact, surface-mount SOT23-5L package (2.8 × 1.75 × 1.3 mm), optimized for space-constrained portable designs and compatible with standard reflow processes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP2210K-18T5L and MCP1702T-1802E/MB, LD2982BM35R uniquely combines sub-100 mV dropout, <1 µA shutdown, and dedicated bypass noise reduction-making it optimal for space- and noise-constrained 1.8 V domains where input headroom and analog integrity are limiting factors.

Availability

LD2982BM35R is available at Aetrix Electronics and suitable for cellular handset power rails, wearable sensor node supplies, PDA core logic domains, and digital camera image sensor bias circuits requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LD2982BM35R 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 components 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 demanding ultra-low dropout, nanoscale shutdown current, and integrated noise suppression without external compensation.

FAQ

What is the minimum input voltage required for LD2982BM35R to maintain 1.8 V output at 50 mA?

The LD2982BM35R requires an input voltage ≥1.92 V to sustain 1.8 V output at 50 mA load, based on its 120 mV typical dropout voltage. At lighter loads (e.g., 1 mA), input can be as low as 1.807 V due to 7 mV dropout. Input must remain ≥2.5 V for guaranteed operation across temperature and process variation per absolute maximum ratings.

Can the INHIBIT pin be left unconnected?

No-the INHIBIT pin has no internal pull-up or pull-down and must not be left floating. To keep the regulator enabled, tie Pin 3 directly to the input voltage (VI). To disable, drive it below 0.18 V with a logic-low source capable of sinking ≤15 µA. Floating operation risks undefined output state and potential instability.

Is a bypass capacitor mandatory for LD2982BM35R operation?

A bypass capacitor is not mandatory for basic regulation but is essential to achieve the specified 30 µV_RMS output noise. Without the 10 nF capacitor between Pin 4 (BYPASS) and GND, output noise rises to ~100 µV_RMS. The regulator remains stable and functional without it, but noise-sensitive analog circuits may experience degraded SNR or increased jitter.

What output capacitor value is required for stability with the 1.8 V version?

For the LD2982BM35R (1.8 V output), a minimum 2.2 µF ceramic capacitor is recommended at the output when using low-ESR types, per ST's application note guidance. However, the device remains stable with as little as 1 µF ceramic capacitor-no ESR minimum is required-making it compatible with small-size X5R/X7R MLCCs commonly used in portable designs.