STMicroelectronics LD39100PURY

Overview

LD39100PURY from STMicroelectronics is an AEC-Q100 qualified 1 A ultra-low-dropout linear regulator in DFN6 (3×3 mm) package, operating from 1.5 V to 5.5 V input and delivering fixed or adjustable output voltages (0.8–4.5 V). It features 200 mV typical dropout at 1 A, 20 µA quiescent current at no load, 30 µV_RMS output noise without bypass capacitor, ±2.0% output voltage tolerance at 25 °C, and logic-controlled shutdown. It is used for post-regulation in automotive infotainment and ADAS power domains.

For engineers reviewing the LD39100PURY datasheet, LD39100PURY pinout, LD39100PURY application, or LD39100PURY equivalent, key selection criteria include dropout performance under 1 A load, thermal shutdown threshold (160 °C), PG pin open-drain behavior with 0.92×V_OUT rising-edge threshold, stability with 1 µF ceramic output capacitor, and wettable flank compatibility for automated optical inspection in automotive PCB assembly.

Technical Context

The LD39100PURY implements a PMOS pass transistor architecture enabling ultra-low dropout and near-zero reverse current during shutdown. Its bandgap reference and error amplifier drive the pass element with internal current limiting (2.5 A short-circuit) and thermal foldback activating at 160 °C with 20 °C hysteresis.

It integrates dual protection functions: overcurrent limiting via constant-current foldback and junction-temperature-based shutdown with automatic recovery. The Power Good (PG) pin provides open-drain status signaling referenced to V_ADJ or V_OUT, requiring external pull-up (100 kΩ–1 MΩ), while EN pin accepts TTL/CMOS logic levels (V_IL ≤ 0.4 V, V_IH ≥ 0.9 V) with <100 nA input leakage.

Key Specifications

Pinout & Package

LD39100PURY is housed in a thermally enhanced DFN6 (3×3 mm) package with wettable flanks and an exposed thermal pad that must be soldered to a GND plane for optimal thermal performance and mechanical reliability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B122MR-G, LD39100PURY delivers 5× higher output current and full automotive qualification; versus ADM7172ACPZ-R7, it offers lower cost, smaller DFN6 footprint, and wettable flanks for AOI - making it optimal for cost-sensitive, high-volume automotive LDO deployments.

Availability

LD39100PURY is available at Aetrix Electronics and suitable for automotive infotainment, ADAS camera modules, and telematics control units requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for LD39100PURY 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 power management applications.

LD39100PURY belongs to ST's automotive-grade LDO portfolio, engineered specifically for post-regulation in safety-critical vehicle subsystems where low noise, high reliability, and AEC-Q100 compliance are mandatory.

FAQ

What is the minimum output capacitance required for stability?

The LD39100PURY is stable with a minimum 1 µF ceramic output capacitor (X5R/X7R dielectric) having ESR between 0 and 150 mΩ. Capacitor placement must be adjacent to the V_OUT pin with short, low-inductance traces to GND. Larger values improve transient response but do not affect stability margins.

Does LD39100PURY support adjustable output voltage?

Yes - the LD39100PURY is available in both fixed-output and adjustable versions. The adjustable variant uses the ADJ pin (not present on LD39100PURY, which is fixed-output) with external resistor divider to set V_OUT from 0.8 V to 4.5 V. LD39100PURY itself is a fixed-output variant; confirm part number suffix for adjustability.

How does the Power Good (PG) pin behave during enable/disable transitions?

When EN is pulled low, the PG pin enters high-impedance state regardless of V_OUT level - preventing unwanted current draw. When EN is high and V_OUT rises above 0.92×V_OUT, PG goes high-Z; if V_OUT drops below 0.8×V_OUT, PG pulls low (≤0.4 V at 6 mA sink). An external pull-up resistor (100 kΩ–1 MΩ) is mandatory.

Is thermal derating required for continuous 1 A operation?

Yes - at ambient temperatures above 65 °C, output current must be reduced to maintain T_J ≤ 125 °C. With R_thJA = 55 °C/W and 1 A load at V_IN = 5.5 V, V_OUT = 3.3 V, power dissipation is 2.2 W, limiting usable ambient to ~80 °C on standard 2-layer PCB. Use thermal vias and copper pour to improve heat spreading.