STMicroelectronics LD39115J15R

Overview

LD39115J15R from STMicroelectronics is a 150 mA ultra-low-noise, low-quiescent-current LDO voltage regulator delivering a fixed 1.5 V output. It operates from 1.5 V to 5.5 V input, features 80 mV typical dropout at 100 mA, 33 µV_RMS noise (1–100 kHz), ±2.0% output tolerance at 25 °C, and logic-controlled shutdown consuming ≤1 µA in off mode. It powers sensitive RF and analog circuitry in portable battery-powered systems.

For engineers reviewing the LD39115J15R datasheet, LD39115J15R pinout, LD39115J15R application, or LD39115J15R equivalent, key selection criteria include dropout performance under light-to-moderate load, sub-µA shutdown current, ceramic-capacitor compatibility (1 µF C_OUT), thermal robustness up to 125 °C junction, and enable-input logic thresholds validated across temperature.

Technical Context

The LD39115J15R uses a bandgap-referenced feedback loop with internal trimming to maintain 1.5 V output accuracy within ±2.0% at 25 °C and ±3.0% over –40 °C to 125 °C. Its flip-chip 4-bump construction enables compact 0.8 × 0.8 mm footprint and low thermal resistance (R_thJA = 180 °C/W).

It integrates active enable control (EN pin), thermal shutdown (160 °C trip, 20 °C hysteresis), short-circuit current limiting (~200 mA), and ESD protection (4 kV HBM). Supply voltage rejection is 74 dB at 1 kHz and 67 dB at 10 kHz for V_OUT = 1.5 V, rolling off above 10 kHz.

Key Specifications

Pinout & Package

LD39115J15R uses a flip-chip 4-bump package (0.8 × 0.8 mm, 0.4 mm pitch), optimized for minimal PCB area and thermal performance. No external heatsink required for ≤150 mA loads at ambient ≤85 °C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B152MR-G and RT9013-15GB, LD39115J15R delivers superior low-noise performance (33 µV_RMS), lowest dropout (80 mV), smallest footprint (0.8 × 0.8 mm), and lowest shutdown current (<1 µA), making it optimal for miniaturized, battery-critical, and noise-sensitive applications.

Availability

LD39115J15R is available at Aetrix Electronics and suitable for wireless sensor nodes, wearable health monitors, industrial IoT gateways, and automotive cabin peripherals requiring stable component supply, long-term lifecycle support, and AEC-Q200-aligned reliability.

Supply support for LD39115J15R 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 devices for industrial, automotive, and consumer markets.

LD39115J15R belongs to ST's LD39xx ultra-low-noise LDO family, engineered specifically for powering noise-sensitive analog and RF circuitry in battery-operated portable and embedded systems where efficiency, size, and signal integrity are critical.

FAQ

What is the minimum input voltage required for LD39115J15R to regulate 1.5 V output?

The LD39115J15R requires a minimum input voltage of 1.5 V, but stable regulation demands headroom equal to its dropout voltage. At 100 mA load, typical dropout is 80 mV, so VIN ≥ 1.58 V ensures regulation. The absolute minimum specified VIN is 1.5 V, though operation below 1.58 V may result in reduced output accuracy or dropout behavior.

Can LD39115J15R be used with tantalum or aluminum electrolytic capacitors instead of ceramic?

No - the LD39115J15R is optimized and characterized for stability with 1 µF ceramic capacitors (X5R/X7R). Tantalum or aluminum electrolytics introduce ESR that can destabilize the control loop, potentially causing oscillation. The datasheet explicitly specifies ceramic-only compatibility and provides ESR vs. capacitance stability zones confirming this requirement.

How does the enable pin (EN) behave over temperature?

The EN pin has guaranteed logic thresholds: V_EN(H) ≥ 0.9 V and V_EN(L) ≤ 0.4 V across –40 °C to 125 °C. Figure 13 shows V_EN(H) decreases slightly with temperature (≈0.85 V at 125 °C), remaining safely above 0.8 V; V_EN(L) stays below 0.4 V. This ensures robust enable/disable control in automotive and industrial thermal environments.

Is LD39115J15R pin-compatible with other variants in the LD39115J series?

Yes - all LD39115J variants (e.g., LD39115J12R, LD39115J18R) share identical flip-chip 4-bump package, pinout (EN, GND, IN, OUT), and footprint. Only the trimmed output voltage differs. This enables drop-in replacement during design iteration or voltage optimization without PCB changes.