STMicroelectronics LD39015M25R

Overview

LD39015M25R from STMicroelectronics is a 2.5 V, 150 mA ultra-low-noise LDO voltage regulator in SOT23-5L package, featuring 80 mV typical dropout at 100 mA, 18 µA quiescent current at no load, and 29 µVRMS output noise without bypass capacitor. It delivers ±2.0% output accuracy at 25 °C and operates across -40 °C to 125 °C for battery-powered portable electronics.

For engineers reviewing the LD39015M25R datasheet, LD39015M25R pinout, LD39015M25R application, or LD39015M25R equivalent, key selection criteria include dropout voltage under 100 mA load, shutdown current <1 µA, ceramic capacitor compatibility (1 µF), PSRR of 65 dB at 1 kHz, and thermal protection with 160 °C shutdown threshold.

Technical Context

The LD39015M25R employs a bandgap reference trimmed to 1.22 V with internal resistor divider (R1/R2) to set 2.5 V output. Its enable-controlled NMOS pass transistor enables fast 30 µs turn-on and sub-1 µA OFF-mode current, while thermal foldback and short-circuit constant-current limiting (350 mA) ensure robustness.

Stability is guaranteed with 1 µF ceramic output capacitor across full load (1–150 mA) and input range (1.5–5.5 V). PSRR remains ≥62 dB up to 10 kHz, and noise spectral density stays below 800 nV/√Hz from 100 Hz to 100 kHz at 10 mA load.

Key Specifications

Pinout & Package

SOT23-5L surface-mount package: 2.95 mm × 1.60 mm footprint, 1.45 mm height, thermal resistance R_thJA = 255 °C/W, RoHS-compliant ECOPACK® grade.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6206P252MR and RT9193-25GB, the LD39015M25R uniquely combines ultra-low noise (29 µVRMS), sub-1 µA shutdown, and integrated thermal/short-circuit protection in a standard SOT23-5L footprint - making it optimal for space-constrained, battery-critical, and safety-aware designs.

Availability

LD39015M25R is available at Aetrix Electronics and suitable for wearable health monitors, Bluetooth LE sensor nodes, industrial handheld scanners, and smart home motion detectors requiring stable component supply across extended product lifecycles.

Supply support for LD39015M25R 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 LD39015 series belongs to ST's high-efficiency, low-noise LDO portfolio targeting battery-powered portable electronics - engineered specifically for minimal power loss, maximum noise immunity, and seamless integration with modern ultra-low-power MCUs and sensors.

FAQ

What is the minimum input voltage required for stable 2.5 V output at 150 mA load?

The LD39015M25R maintains regulation down to VIN = VOUT + VDROP. With 100 mV max dropout at 150 mA (per datasheet Table 5), minimum input is 2.6 V. At 100 mA, typical dropout is 80 mV, so 2.58 V suffices. Below 2.5 V input, output collapses linearly per dropout curve in Figure 6.

Can the LD39015M25R operate with a 1 µF ceramic output capacitor only, or is an input capacitor also required?

A 1 µF ceramic input capacitor is mandatory per Section 3 (Typical Application) and Figure 3. Without it, line transient response degrades and PSRR drops significantly above 10 kHz. The device is stable with 1 µF CIN and 1 µF COUT - both must be X5R/X7R ceramics rated ≥6.3 V.

Does the NC pin (Pin 4) require any PCB layout treatment?

Pin 4 is internally unconnected and must not be soldered to any net. ST recommends leaving it floating per Table 2 and Figure 2. Routing traces or copper pours beneath or adjacent to Pin 4 is acceptable, but it must never be tied to GND, VOUT, or any other signal to avoid parasitic coupling or ESD path disruption.

How does thermal shutdown behave during sustained overload, and is automatic recovery supported?

Thermal shutdown activates at 160 °C junction temperature with 20 °C hysteresis (Section 5, Table 5). Once tripped, the device turns off completely (<1 µA current) and remains off until junction cools to ≤140 °C, then resumes normal regulation automatically - no external reset or enable toggle needed.