STMicroelectronics LD2982AM285R

Overview

LD2982AM285R from STMicroelectronics is a 50 mA fixed-output low-dropout linear voltage regulator delivering 2.85 V with ±1% tolerance at 25 °C, featuring 120 mV dropout at 50 mA, 30 µV_RMS output noise (with 10 nF bypass capacitor), and logic-controlled inhibit shutdown reducing quiescent current to <1 µA. It serves as a local power rail regulator in portable battery-powered systems requiring ultra-low noise and standby efficiency.

For engineers reviewing the LD2982AM285R datasheet, LD2982AM285R pinout, LD2982AM285R application, or LD2982AM285R equivalent, key selection criteria include dropout performance at light load, noise suppression capability with external bypass, TTL-compatible inhibit control timing, and SOT23-5L footprint compatibility in space-constrained designs.

Technical Context

The LD2982AM285R employs a PNP pass transistor architecture enabling ultra-low dropout (7 mV at 1 mA) and stable operation with only 1 µF ceramic output capacitance. Its internal feedback network sets a precise 2.85 V output, while the dedicated Bypass pin accepts a 10 nF capacitor to reduce thermal noise to 30 µV_RMS across 300 Hz–50 kHz.

Inhibit functionality is implemented via Pin 3 (INHIBIT), which disables regulation when pulled below 0.15 V (TTL-low), cutting supply current to sub-µA levels without requiring internal pull-up. The device operates across –40 °C to +125 °C junction temperature and includes internal current and thermal limiting for robustness.

Key Specifications

Pinout & Package

SOT23-5L package: 5-pin surface-mount, 1.45 mm height, 0.95 mm pitch, ECOPACK®-compliant lead-free finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP2210K-2.85TRG1 and MCP1703T-285E/MB, the LD2982AM285R uniquely combines sub-µA inhibit current, 30 µV_RMS noise with bypass, and 120 mV dropout-making it optimal for space- and noise-constrained battery-powered endpoints where every microamp and microvolt matters.

Availability

LD2982AM285R is available at Aetrix Electronics and suitable for cellular handset power rails, portable medical sensor nodes, industrial PLC I/O modules, and automotive cabin camera modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LD2982AM285R 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 silicon solutions for automotive, industrial, and consumer markets since 1987.

The LD2982 series belongs to ST's precision low-dropout regulator product line, engineered specifically for ultra-low-noise, low-quiescent-current applications in battery-powered and thermally constrained electronic systems.

FAQ

What is the minimum input voltage required for regulation at 2.85 V output?

The LD2982AM285R maintains regulation with input voltages as low as 2.5 V, enabled by its ultra-low dropout of just 7 mV at 1 mA load. At full 50 mA output, dropout rises to 120 mV, meaning 2.97 V input is sufficient. This allows operation directly from partially discharged single-cell Li-ion batteries down to ~3.0 V.

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

The Bypass pin connects to an internal noise-reduction circuit that filters reference voltage fluctuations. A 10 nF ceramic capacitor between Bypass and GND lowers integrated output noise from ~100 µV_RMS to 30 µV_RMS over 300 Hz–50 kHz. ST specifies X7R or C0G dielectrics; capacitor must be placed within 2 mm of the pin with short, low-inductance traces.

Can the INHIBIT pin be left unconnected if shutdown functionality is not needed?

No-the INHIBIT pin must never be left floating. When unused, it must be tied directly to the IN pin to maintain regulation. Floating the pin risks unpredictable shutdown due to noise coupling, as the input has no internal pull-up and logic thresholds are tightly specified (V_IL = 0.15 V, V_IH = 2 V).

Is the LD2982AM285R compatible with ceramic output capacitors, and what ESR range is acceptable?

Yes-the LD2982AM285R is optimized for ceramic output capacitors with ESR as low as 5 mΩ. For 2.85 V output, ST recommends ≥2.2 µF X7R/C0G ceramics. Unlike older LDOs, it does not require added series resistance to stabilize low-ESR ceramics, simplifying layout and reducing component count.