STMicroelectronics LD2982AM47R

Overview

LD2982AM47R from STMicroelectronics is a 50 mA fixed-output low-dropout (LDO) linear voltage regulator with 1.8 V output, logic-controlled inhibit function, and ultra-low noise (30 µV_RMS). It features 120 mV dropout at 50 mA, 75 µA quiescent current at 1 mA load, ±1% output tolerance at 25 °C, and operates across –40 °C to +125 °C for battery-powered portable electronics.

For engineers reviewing the LD2982AM47R datasheet, LD2982AM47R pinout, LD2982AM47R application, or LD2982AM47R equivalent, key selection criteria include its TTL-compatible INHIBIT control, 1 µF minimum ceramic output capacitor requirement, low-ESR stability, sub-1 µA shutdown current, and SOT23-5L footprint compatibility in space-constrained designs.

Technical Context

The LD2982AM47R 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 tight regulation over input voltage (2.5–16 V) and temperature (–40 to +125 °C). Its internal feedback network sets a precise 1.8 V output with ±1% initial accuracy.

It integrates thermal and current limiting, supports external bypass capacitance (10 nF to GND on pin 4) for noise reduction to 30 µV_RMS, and accepts TTL-level inhibit signals (V_IL ≤ 0.15 V, V_IH ≥ 2 V) on pin 3 to achieve <1 µA shutdown current-critical for system-level power gating in portable devices.

Key Specifications

Pinout & Package

LD2982AM47R is housed in a compact, surface-mount SOT23-5L package (2.8 × 1.75 × 1.3 mm), optimized for high-density PCB layouts and automated assembly. The package is RoHS-compliant and ECOPACK®-certified.

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, LD2982AM47R uniquely combines sub-100 µA I_Q, <125 mV dropout, integrated bypass pin for 30 µV_RMS noise, and TTL inhibit-all in SOT23-5L-making it optimal for noise-sensitive, battery-constrained 1.8 V systems.

Availability

LD2982AM47R is available at Aetrix Electronics and suitable for cellular handset power rails, portable medical sensor nodes, industrial IoT edge controllers, and wearable fitness trackers requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for LD2982AM47R 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 analog, MCU, power, and sensing solutions 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, sub-µA shutdown, and high PSRR in miniature packages.

FAQ

What is the minimum input voltage required for LD2982AM47R to regulate 1.8 V output at 50 mA?

The LD2982AM47R requires an input voltage ≥1.92 V to maintain regulation at 50 mA load, based on its 120 mV typical dropout voltage. At lighter loads (e.g., 1 mA), only 1.807 V input is needed due to 7 mV dropout. Input must remain ≥2.5 V per absolute maximum ratings to avoid damage.

Can LD2982AM47R operate without the 10 nF bypass capacitor on pin 4?

Yes-it will regulate correctly without the 10 nF bypass capacitor, but output noise increases from 30 µV_RMS to approximately 120 µV_RMS. The capacitor is optional for noise-critical applications (e.g., ADC references, RF bias rails) but not required for basic digital logic supply.

Is the INHIBIT pin internally pulled up or down?

No-the INHIBIT pin has no internal pull-up or pull-down. It must be actively driven: ≤0.15 V to disable (shutdown), ≥2 V to enable (regulation). Leaving it floating may cause erratic operation or increased leakage; ST recommends tying to VIN if unused.

What is the maximum allowable output capacitor ESR for stable operation?

The LD2982AM47R is designed for low-ESR ceramic capacitors (typical ESR <100 mΩ). For 2.2 µF output capacitance, ESR should not exceed 200 mΩ across –40 to +125 °C. Higher ESR risks oscillation; tantalum capacitors require careful ESR verification per Section 6.3 of the datasheet.