STMicroelectronics LD39115J14R

Overview

LD39115J14R from STMicroelectronics is a 150 mA ultra-low-noise, low-quiescent-current LDO voltage regulator delivering a fixed 1.4 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 accuracy at 25 °C, and logic-controlled shutdown with <1 µA off-mode current. It powers core rails in space-constrained, battery-operated portable electronics requiring stable low-voltage bias.

For engineers reviewing the LD39115J14R datasheet, LD39115J14R pinout, LD39115J14R application, or LD39115J14R equivalent, this page provides verified electrical specs, thermal behavior, enable timing, ceramic capacitor compatibility, and real-world load/line transient performance - all critical for low-power wearable and IoT power rail design.

Technical Context

The LD39115J14R uses a bandgap-referenced feedback loop with internal trimming to maintain 1.4 V output across –40 °C to 125 °C junction temperature. Its flip-chip 4-bump construction enables minimal PCB footprint (0.8 × 0.8 mm) and low thermal resistance (R_thJA = 180 °C/W).

It integrates short-circuit constant-current limiting (200 mA typ.), thermal shutdown (160 °C with 20 °C hysteresis), and ESD protection (4 kV HBM). The EN pin accepts logic-level control (V_IL ≤ 0.4 V, V_IH ≥ 0.9 V) with 30 µs turn-on time and supports 1 µF ceramic output capacitance without external compensation.

Key Specifications

Pinout & Package

LD39115J14R uses a flip-chip 4-bump package (0.8 mm × 0.8 mm, 0.4 mm pitch) with no external leads - mounting requires solder bumps directly to PCB pads per Figure 37 footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B142MR-G and RT9013-14GB, LD39115J14R delivers superior noise performance (33 µV_RMS vs. ≥45 µV_RMS), tighter output tolerance (±2% vs. ±3%), and integrated thermal protection - making it optimal for noise-sensitive, thermally constrained, and long-life battery applications.

Availability

LD39115J14R is available at Aetrix Electronics and suitable for wearable health sensors, Bluetooth LE modules, and industrial wireless nodes requiring stable component supply with guaranteed long-term availability and full traceability.

Supply support for LD39115J14R 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 LD39115J series belongs to ST's high-performance LDO portfolio targeting ultra-low-power, low-noise portable electronics - engineered specifically for battery longevity, compact form factor, and robustness in thermally demanding environments.

FAQ

What is the minimum input voltage required for regulation at 1.4 V output?

The LD39115J14R requires VIN ≥ VOUT + VDROP to maintain regulation. With 80 mV typical dropout at 100 mA, minimum VIN is 1.48 V under that load. At light loads (<1 mA), dropout drops below 50 mV, allowing stable operation down to ~1.45 V input. Absolute minimum VIN per datasheet is 1.5 V for full specification compliance.

Can LD39115J14R be used with a 0.47 µF ceramic output capacitor?

No - the device requires ≥1 µF ceramic output capacitance for stability, as confirmed in Section 5 (Electrical Characteristics) and Figure 35 (ESR vs. COUT stability zone). Using 0.47 µF risks oscillation or poor transient response. ST specifies 1–22 µF ceramic capacitors with ESR <2 Ω at 100 kHz.

How does the enable pin behave during power-up sequencing?

The EN pin has a defined turn-on threshold: V_EN(H) ≥ 0.9 V (min) over temperature. Once exceeded, the device achieves 95% of nominal output in 30 µs (TON). No external pull-up is needed - internal bias ensures default disable until driven high. EN must be actively controlled to avoid unintended startup.

Is LD39115J14R qualified for automotive applications?

While rated for –40 °C to +125 °C junction temperature and featuring automotive-grade ESD (4 kV HBM), LD39115J14R is not AEC-Q100 qualified. It is intended for industrial and consumer portable equipment. For automotive use, ST recommends the pin-compatible AEC-Q100 qualified LD39115AJ14R variant with identical electrical specs and extended reliability testing.