STMicroelectronics LD2982BM47R

Overview

LD2982BM47R from STMicroelectronics is a 50 mA, 1.8 V fixed-output low-dropout linear voltage regulator with logic-controlled inhibit function, 120 mV dropout at 50 mA, 30 µV_rms output noise, and SOT23-5L package - designed for ultra-low-noise power supply in portable battery-powered systems such as PDAs and camcorders.

For engineers reviewing the LD2982BM47R datasheet, LD2982BM47R pinout, LD2982BM47R application, or LD2982BM47R equivalent, key selection criteria include dropout voltage under light/heavy load, quiescent current in active/sleep modes, bypass capacitor noise reduction, and TTL-compatible inhibit control timing behavior.

Technical Context

The LD2982BM47R integrates a PNP pass transistor enabling ultra-low dropout (7 mV at 1 mA, 120 mV at 50 mA) and operates with input voltages from 2.5 V to 16 V. Its internal feedback network sets a precise 1.8 V output with ±1% tolerance at 25 °C (A-grade).

It features a dedicated INHIBIT pin (Pin 3) with TTL-compatible thresholds (V_IL ≤ 0.15 V, V_IH ≥ 2 V) that reduces quiescent current to <1 µA in shutdown, and a Bypass pin (Pin 4) accepting a 10 nF capacitor to suppress thermal noise to 30 µV_rms (300 Hz–50 kHz).

Key Specifications

Pinout & Package

SOT23-5L surface-mount package (2.8 × 1.75 × 1.3 mm), RoHS-compliant and ECOPACK® certified, optimized for thermal performance (R_thJA = 255 °C/W) and PCB area efficiency.

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 LD2982BM47R uniquely combines sub-1 µA shutdown, 30 µV_rms noise via integrated bypass pin, and 120 mV dropout - making it optimal for compact, battery-critical systems demanding simultaneous low power and high signal integrity.

Availability

LD2982BM47R is available at Aetrix Electronics and suitable for portable medical devices, industrial handheld terminals, wearable sensor nodes, and consumer communication equipment requiring stable component supply across extended temperature and long-lifecycle programs.

Supply support for LD2982BM47R 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-precision, ultra-low-noise LDO family targeting battery-powered portable electronics where minimal dropout, microampere quiescent current, and sub-50 µV_rms noise are critical design requirements.

FAQ

What is the minimum input voltage required for stable 1.8 V output at 50 mA load?

The LD2982BM47R requires a minimum input voltage of 1.92 V (1.8 V + 120 mV dropout) to maintain regulation at 50 mA. At lighter loads (e.g., 1 mA), dropout falls to 7 mV, allowing stable operation down to 1.807 V input - enabling compatibility with deeply discharged single-cell lithium batteries.

How does the BYPASS pin reduce output noise, and what capacitor value is required?

The BYPASS pin connects an external 10 nF ceramic capacitor to ground, which shunts high-frequency thermal noise from the internal bandgap reference amplifier. This reduces integrated output noise from >100 µV_rms to 30 µV_rms (300 Hz–50 kHz bandwidth), as verified in ST's electrical characteristics table and application note section 6.5.

Can the INHIBIT pin be left unconnected, or does it require a pull-up?

The INHIBIT pin must never be left floating. When unused, it must be tied directly to the IN pin (not via a resistor) to ensure reliable ON-state operation. Leaving it open risks undefined logic state, intermittent shutdown, and potential output instability due to noise coupling - as explicitly warned in Section 6.5 of the datasheet.

Is the LD2982BM47R compatible with ceramic output capacitors below 1 µF?

No - the datasheet specifies a minimum 1 µF ceramic output capacitor for stability with 1.8 V output versions. Using smaller values risks oscillation; if space constraints require reduced capacitance, a series resistor (per Section 6.3) must be added to emulate the ESR needed for phase margin, but this degrades transient response and is not recommended for production designs.