STMicroelectronics LD39100PU25RY

Overview

LD39100PU25RY from STMicroelectronics is an AEC-Q100 qualified, 1 A ultra-low-dropout linear regulator in DFN6 (3×3 mm) package with fixed 2.5 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 automotive post-regulation and low-power battery-powered systems requiring stable low-noise supply.

For engineers reviewing the LD39100PU25RY datasheet, LD39100PU25RY pinout, LD39100PU25RY application, or LD39100PU25RY equivalent, key selection criteria include dropout performance at 1 A load, PG threshold behavior (0.92×VOUT), thermal shutdown at 160 °C, stability with 1 µF ceramic output capacitor, and enable logic compatibility with 0.4 V low / 0.9 V high thresholds.

Technical Context

The LD39100PU25RY implements a PMOS pass transistor architecture enabling ultra-low dropout (200 mV typ. at 1 A) and rail-to-rail input operation down to 1.5 V. Its bandgap reference and error amplifier deliver tight output regulation (±2.0% at 25 °C) across –40 °C to 125 °C junction temperature.

It integrates logic-controlled enable (EN), open-drain power-good (PG) with 0.92×VOUT rising-edge threshold, internal current limiting (2.5 A short-circuit), and thermal shutdown (160 °C with 20 °C hysteresis). The device achieves 70 dB PSRR at 1 kHz and 30 µV_RMS output noise (10 Hz–100 kHz) without bypass capacitor.

Key Specifications

Pinout & Package

LD39100PU25RY uses the DFN6 (3×3 mm) wettable flank package with exposed thermal pad connected to GND. Pin 1 is EN (enable), Pin 2 is GND, Pin 3 is PG (power-good open-drain), Pin 4 is VOUT, Pin 5 is NC (no connect), and Pin 6 is VIN. The exposed pad must be soldered to a GND copper pour for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B252MR-G, LD39100PU25RY adds PG monitoring and superior thermal dissipation; versus ADP1740ACPZ-2.5-R7, it delivers 12× lower quiescent current-making it optimal for always-on automotive modules where standby power budget is sub-100 µW.

Availability

LD39100PU25RY is available at Aetrix Electronics and suitable for automotive infotainment, industrial sensor nodes, and printed circuit board test fixtures requiring stable component supply, AEC-Q100 compliance, and low-noise 2.5 V regulation.

Supply support for LD39100PU25RY 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.

LD39100PU25RY belongs to ST's high-reliability LDO portfolio targeting automotive post-regulation and battery-powered systems-emphasizing ultra-low dropout, low noise, and AEC-Q100 qualification for mission-critical subsystems.

FAQ

What is the minimum input voltage required for LD39100PU25RY to maintain 2.5 V output at 1 A?

The minimum input voltage is determined by dropout: VIN(min) = VOUT + VDROP = 2.5 V + 0.2 V = 2.7 V (typical). At worst-case 400 mV dropout (–40 °C to 125 °C), VIN must be ≥2.9 V. Input below 1.5 V is prohibited per absolute maximum ratings.

Can LD39100PU25RY operate with a 1 µF output capacitor only, or is additional capacitance required?

Yes-1 µF ceramic capacitor (X5R/X7R, ESR ≤150 mΩ) is sufficient and specified for stability. Larger values improve transient response but are not required. Avoid tantalum or aluminum electrolytics due to ESR and aging effects that may destabilize the control loop.

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

When EN rises above 0.9 V, PG transitions to high-impedance once VOUT reaches ≥0.92×2.5 V (2.3 V). When EN falls below 0.4 V, PG goes high-impedance immediately-even if VOUT remains nominal-to prevent sink current in shutdown. No external pull-down is needed.

Is the exposed thermal pad on LD39100PU25RY electrically connected, and how must it be handled in layout?

Yes-the exposed pad is internally connected to GND and must be soldered to a dedicated GND copper pour using ≥4 thermal vias (0.3 mm diameter) to inner ground layers. Failure to connect it degrades thermal resistance (R_thJA increases from 55 °C/W to >100 °C/W) and risks thermal shutdown under 1 A load.