STMicroelectronics LD39100PU12RY

Overview

LD39100PU12RY from STMicroelectronics is an AEC-Q100 qualified, 1 A ultra-low-dropout linear regulator in DFN6 (3×3 mm) package with fixed 1.2 V output, 200 mV typical dropout at full load, ±2.0% output voltage tolerance at 25 °C, and logic-controlled enable/shutdown. It delivers stable low-noise power for automotive post-regulation and battery-powered systems requiring <1 µA off-mode current and ceramic capacitor compatibility.

For engineers reviewing the LD39100PU12RY datasheet, LD39100PU12RY pinout, LD39100PU12RY application, or LD39100PU12RY equivalent, key selection criteria include dropout voltage at 1 A, quiescent current across temperature, Power Good threshold accuracy, thermal shutdown hysteresis, and stability with 1 µF ceramic output capacitance - all confirmed in DS6257 Rev 9.

Technical Context

The LD39100PU12RY implements a PMOS pass transistor architecture enabling ultra-low dropout (200 mV typ. at 1 A) and near-zero reverse current. Its bandgap reference and error amplifier deliver ±2.0% output accuracy over temperature and load, while internal current limiting and thermal shutdown (160 °C trip, 20 °C hysteresis) ensure robust fault protection.

It integrates a dedicated open-drain Power Good (PG) output with rising-edge threshold at 0.92×VOUT and falling-edge at 0.80×VOUT, plus an enable input (VEN_H = 0.9 V min, VEN_L = 0.4 V max) that reduces total supply current to <1 µA in shutdown - critical for always-on automotive domains.

Key Specifications

Pinout & Package

LD39100PU12RY uses the DFN6 (3×3 mm) wettable flank package with exposed thermal pad connected to GND. The fixed-output version has 6 pins in standard top-view configuration.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A0512PYKAR and NCP1117ST12T3G, LD39100PU12RY uniquely combines 1 A capability, 200 mV dropout, 20 µA quiescent current, AEC-Q100 qualification, and DFN6 wettable flank packaging - making it the only viable option for automotive-grade, high-efficiency 1.2 V post-regulation.

Availability

LD39100PU12RY is available at Aetrix Electronics and suitable for automotive body control modules, infotainment system core rails, and portable diagnostic tools requiring stable component supply with AEC-Q100 compliance, low-noise operation, and extended temperature support.

Supply support for LD39100PU12RY 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 LD39100 belongs to ST's high-performance automotive LDO family, engineered specifically for post-regulation in safety-critical and low-power domains where ultra-low dropout, AEC-Q100 reliability, and sub-µA shutdown are mandatory.

FAQ

What is the maximum allowable input voltage for LD39100PU12RY?

The absolute maximum DC input voltage is 7 V, but the recommended operating range is 1.5 V to 5.5 V per DS6257 Rev 9. Exceeding 5.5 V risks violating the 0.3 V margin above VOUT (1.2 V), potentially damaging the internal pass element or reference circuitry.

Can LD39100PU12RY operate stably with a 1 µF X7R ceramic capacitor on the output?

Yes - the device is explicitly characterized and guaranteed stable with 1 µF X5R/X7R ceramic capacitors having ESR between 0 and 150 mΩ. This is validated across −40 °C to +125 °C and full 10 mA–1 A load range, eliminating need for larger or more expensive capacitor types.

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

When EN is pulled low, PG enters high-impedance state regardless of VOUT level - this prevents unwanted current draw through external pull-up resistors. When EN goes high, PG asserts high-Z only after VOUT reaches ≥0.92×1.2 V (1.104 V), with hysteresis ensuring clean release at 0.96 V.

Is the exposed thermal pad on the DFN6 package required to be soldered to PCB ground?

Yes - the exposed pad must be electrically and thermally connected to a solid GND plane using ≥4 thermal vias (0.3 mm diameter). Failure to do so increases R_thJA beyond the rated 55 °C/W, risking thermal shutdown under 1 A load at ambient >85 °C.