STMicroelectronics LD2982AM50R

Overview

LD2982AM50R from STMicroelectronics is a 50 mA fixed-output low-dropout linear voltage regulator with 1.8 V output, TTL-compatible inhibit control (Pin 3), 120 mV dropout at 50 mA, 30 µV_RMS output noise (with 10 nF bypass capacitor), and SOT23-5L package. It delivers ultra-low quiescent current (75 µA at 1 mA load) and supports battery-powered portable electronics requiring stable, low-noise local regulation.

For engineers reviewing the LD2982AM50R datasheet, LD2982AM50R pinout, LD2982AM50R application, or LD2982AM50R equivalent, key selection criteria include dropout performance under light/heavy load, shutdown leakage (<1 µA), bypass-capacitor–dependent noise reduction, and compatibility with low-ESR ceramic output capacitors down to 2.2 µF for 1.8 V operation.

Technical Context

The LD2982AM50R employs a PNP pass transistor architecture enabling ultra-low dropout (as low as 7 mV at 1 mA) and minimal line/load regulation drift (0.003 %/V typical). Its internal feedback network uses implanted resistors (R1 = 42.6 kΩ, R2 = 51.15 kΩ) to set the 1.8 V output with ±1 % tolerance at 25 °C (A-grade).

It integrates thermal and current limiting, supports reverse-current blocking (no body diode), and features an active-low INHIBIT input with defined logic thresholds (V_IL ≤ 0.15 V, V_IH ≥ 2 V) and sub-15 µA input current-enabling precise system-level power gating without external pull-ups.

Key Specifications

Pinout & Package

Supplied in compact SOT23-5L package (2.8 × 1.6 × 1.3 mm, 5-pin surface-mount), optimized for space-constrained portable PCBs and compatible with standard reflow profiles.

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 LD2982AM50R uniquely combines sub-1 µA shutdown, 120 mV dropout, and bypass-enabled 30 µV_RMS noise-making it optimal for battery-powered systems demanding simultaneous low power, high efficiency, and analog-grade cleanliness.

Availability

LD2982AM50R is available at Aetrix Electronics and suitable for mobile baseband power, wearable sensor supply, PDA application processor core, and digital camera image sensor bias applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LD2982AM50R 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-dropout regulator product line, engineered specifically for ultra-low-noise, low-power portable electronics where battery life, thermal footprint, and signal integrity are critical design constraints.

FAQ

What is the minimum output capacitance required for stable operation at 1.8 V?

The LD2982AM50R requires a minimum 2.2 µF ceramic capacitor with low ESR on the output pin for stable 1.8 V operation. This value is specified in ST's application notes (Section 6.3) and validated across temperature and load conditions. Using smaller values risks oscillation unless a series resistor is added per design guidance.

How does the INHIBIT pin behave when left unconnected?

The INHIBIT pin has no internal pull-up or pull-down; leaving it floating causes undefined operation and potential malfunction. ST explicitly states it "cannot be left floating" and mandates connection to either VI (to enable) or GND (to disable). Floating operation may result in erratic output or excessive quiescent current.

Can the LD2982AM50R be used with input voltages below 2.5 V?

No-the absolute minimum operating input voltage is 2.5 V per Table 4 (Absolute Maximum Ratings) and electrical characterization conditions. At 1.8 V output, the minimum functional input is VO + V_DROP, but the device is not characterized or guaranteed below 2.5 V input, and startup behavior is undefined in that region.

Is the 30 µV_RMS noise specification achievable without the bypass capacitor?

No-the 30 µV_RMS noise figure is measured with a 10 nF capacitor connected between the BYPASS pin and GND. Without this capacitor, output noise rises significantly-ST does not specify the un-bypassed value, but typical increase exceeds 3×. The BYPASS pin is essential to achieve the stated low-noise performance.