STMicroelectronics LD39115J10R

Overview

LD39115J10R from STMicroelectronics is a 150 mA ultra-low-noise, low-quiescent-current LDO voltage regulator with fixed 1.0 V output, 80 mV typical dropout at 100 mA, 20 µA typical quiescent current at no load, and 33 µV_RMS noise (1 kHz–100 kHz). It operates from 1.5 V to 5.5 V input and features logic-controlled shutdown, internal thermal/current protection, and ceramic capacitor compatibility - deployed in battery-powered mobile and portable systems requiring stable, clean power rails.

For engineers reviewing the LD39115J10R datasheet, LD39115J10R pinout, LD39115J10R application, or LD39115J10R equivalent, key selection criteria include dropout voltage under light/heavy load, shutdown leakage (<1 µA), output accuracy (±2.0% @ 25 °C), noise performance at target V_OUT, and flip-chip package thermal behavior in space-constrained PCB layouts.

Technical Context

The LD39115J10R uses a bandgap-referenced feedback loop with internal trimming for ±2.0% output accuracy at 25 °C and ±3.0% over –40 °C to 125 °C. Its enable-controlled NMOS pass transistor enables fast turn-on (30 µs) and sub-1 µA off-mode current, while the flip-chip 4-bump construction delivers low thermal resistance (R_thJA = 180 °C/W) and minimal board footprint (0.8 × 0.8 mm).

Supply voltage rejection is 74 dB at 1 kHz and 67 dB at 10 kHz (V_OUT = 1.5 V), rolling off above 10 kHz; line regulation is 0.01 %/V and load regulation is 0.002 %/mA - confirming high stability across input and load transients in low-power embedded systems.

Key Specifications

Pinout & Package

LD39115J10R 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 leadframe or wire bonds - bumps directly connect die terminals to PCB pads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B102MR-G and RT9013-10GB, LD39115J10R uniquely balances ultra-low noise (33 µV_RMS), sub-µA shutdown, and 0.8 × 0.8 mm flip-chip packaging - making it optimal for miniaturized, battery-sensitive designs where both size and signal integrity are constrained.

Availability

LD39115J10R is available at Aetrix Electronics and suitable for wearable health sensors, Bluetooth LE modules, industrial handheld scanners, and smart home motion detectors requiring stable component supply across multi-year production cycles.

Supply support for LD39115J10R 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 LD39115J series belongs to ST's ultra-low-noise, low-I_Q LDO portfolio, engineered specifically for space-constrained, battery-powered portable electronics demanding high PSRR, tight output accuracy, and minimal standby consumption.

FAQ

What is the minimum input voltage required for LD39115J10R to regulate 1.0 V output?

The LD39115J10R requires VIN ≥ 1.1 V to maintain regulation at full 150 mA load, based on its 80 mV typical dropout voltage. At lighter loads (e.g., 10 mA), dropout drops to ~30 mV, allowing VIN as low as 1.03 V. The absolute minimum operating VIN is 1.5 V per datasheet specifications, ensuring guaranteed performance across temperature and process variation.

Can LD39115J10R be used with a 0.47 µF output capacitor?

No - the LD39115J10R requires a minimum 1 µF ceramic output capacitor (X5R/X7R) for stability, as confirmed in Section 5 (Electrical Characteristics) and Figure 35 (ESR vs. C_OUT). Using 0.47 µF risks phase margin degradation, leading to oscillation or poor transient response; 1 µF is the validated lower bound for all operating conditions.

Does LD39115J10R support adjustable output voltage via external resistors?

No - LD39115J10R is a fixed-output device with internally trimmed 1.0 V regulation. The LD39115J family offers factory-set voltages only (e.g., 1.2 V, 1.4 V, 1.8 V); no version includes feedback pins or external resistor networks for adjustment. For programmable output, consider ST's LD39200 or alternative adjustable LDO families.

How does the enable pin behave during power-up when VIN ramps slowly?

The LD39115J10R's enable threshold is 0.9 V (min) for activation and 0.4 V (max) for shutdown, with hysteresis ensured by internal design. During slow VIN ramp, EN must exceed 0.9 V *after* VIN reaches ≥1.5 V to guarantee proper startup; applying EN high before VIN stabilizes may cause undefined output behavior. A simple RC delay on EN is recommended for synchronized sequencing.