STMicroelectronics LD39100PU33RY

Overview

LD39100PU33RY from STMicroelectronics is an AEC-Q100 qualified, 1 A ultra-low-dropout linear regulator in DFN6 (3×3 mm) package with fixed 3.3 V output, 200 mV typical dropout at 1 A, ±2.0% output voltage tolerance at 25 °C, and 20 µA typical quiescent current at no load-designed for post-regulation in automotive infotainment and ADAS domain controllers.

For engineers reviewing the LD39100PU33RY datasheet, LD39100PU33RY pinout, LD39100PU33RY application, or LD39100PU33RY equivalent, key selection criteria include low-noise operation without bypass capacitor (30 µV_RMS at 0.8 V), logic-controlled shutdown (<1 µA off-mode current), stability with 1 µF ceramic output capacitor, and -40 °C to 125 °C operating junction temperature range.

Technical Context

The LD39100PU33RY implements a PMOS pass transistor architecture enabling ultra-low dropout (200 mV typ. at 1 A) and high PSRR (70 dB at 1 kHz). Its internal bandgap reference and error amplifier deliver tight output regulation across input voltage (1.5–5.5 V), load (0–1 A), and temperature (-40 °C to 125 °C).

It integrates dual protection: constant-current short-circuit limiting (2.5 A typ.) and thermal shutdown with 160 °C trip point and 20 °C hysteresis. The open-drain Power Good (PG) output provides programmable monitoring (92% rising / 80% falling threshold) requiring external pull-up.

Key Specifications

Pinout & Package

LD39100PU33RY uses the DFN6 (3×3 mm) package with exposed thermal pad connected to GND. Pin 1 is EN (enable), Pin 2 is GND, Pin 3 is PG (Power Good), Pin 4 is V_OUT, Pin 5 is NC (no connect), Pin 6 is V_IN.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B332MR-G, LD39100PU33RY adds PG monitoring and automotive qualification at lower I_Q; compared with ADM7172ACPZ-3.3-R7, it delivers AEC-Q100 compliance and 1/12th the quiescent current while meeting noise requirements for non-RF analog stages.

Availability

LD39100PU33RY is available at Aetrix Electronics and suitable for automotive infotainment systems, ADAS domain controllers, and industrial vehicle telematics requiring stable component supply across extended temperature and long lifecycle demands.

Supply support for LD39100PU33RY 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, specializing in automotive, industrial, and power management solutions with broad manufacturing and R&D infrastructure.

LD39100PU33RY belongs to ST's automotive-grade LDO portfolio, engineered specifically for post-regulation in safety-critical vehicle subsystems where low noise, ultra-low dropout, and AEC-Q100 reliability are mandatory.

FAQ

What is the minimum input voltage required for LD39100PU33RY to maintain 3.3 V output at 1 A load?

The minimum input voltage is 3.5 V, calculated as V_OUT + V_DROP = 3.3 V + 0.2 V (typical dropout). At -40 °C to 125 °C, max dropout is 400 mV, so 3.7 V input is recommended for guaranteed regulation across temperature. Input below 1.5 V is prohibited per absolute maximum ratings.

Can LD39100PU33RY operate with a 1 µF output capacitor only, or is additional capacitance required?

Yes, LD39100PU33RY is fully stable with a single 1 µF X5R/X7R ceramic capacitor on V_OUT, provided its ESR remains ≤150 mΩ across -40 °C to 125 °C. Larger values improve transient response but are not required for stability-unlike many legacy LDOs needing ≥10 µF.

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

When EN rises above 0.9 V, PG transitions to high-impedance after V_OUT reaches 92% of 3.3 V (≈3.036 V). When EN falls below 0.4 V, PG immediately enters high-impedance-no pull-down current flows. PG remains inactive (high-Z) in shutdown to avoid loading external logic.

Is the exposed thermal pad on LD39100PU33RY electrically connected, and how must it be handled on the PCB?

Yes, the exposed pad is internally connected to GND and must be soldered to a dedicated PCB GND copper pour using ≥4 thermal vias (0.3 mm diameter) to inner ground layers. Failure to connect it degrades thermal resistance by >40 °C/W and risks thermal shutdown under 1 A load.