STMicroelectronics LD39100PU18RY

Overview

LD39100PU18RY from STMicroelectronics is an AEC-Q100 qualified ultra-low-dropout linear regulator delivering 1 A output current with 200 mV typical dropout at full load, 20 µA typical quiescent current at no load, ±2.0% output voltage tolerance at 25 °C, and stable operation with only 1 µF ceramic output capacitor. It operates across 1.5 V to 5.5 V input and delivers fixed 1.8 V output for automotive post-regulation and low-power embedded systems.

For engineers reviewing the LD39100PU18RY datasheet, LD39100PU18RY pinout, LD39100PU18RY application, or LD39100PU18RY equivalent, key selection criteria include its automotive-grade qualification, sub-1 µA shutdown current, 30 µV_RMS noise without bypass capacitor, power-good flag functionality, and DFN6 (3×3 mm) wettable flank package compatibility with automated optical inspection.

Technical Context

The LD39100PU18RY implements a PMOS pass transistor architecture enabling ultra-low dropout and near-zero reverse current during shutdown. Its internal bandgap reference and error amplifier maintain tight output regulation across –40 °C to 125 °C junction temperature, with integrated thermal shutdown (160 °C) and constant-current short-circuit protection.

It features dual logic-controlled functions: EN pin enables active operation above 0.9 V and forces <1 µA off-mode current below 0.4 V; PG pin provides open-drain power-good status referenced to 92% of nominal output (1.656 V), requiring external pull-up. The device achieves 70 dB PSRR at 1 kHz and maintains stability with 1 µF X5R/X7R ceramic capacitors on both input and output.

Key Specifications

Pinout & Package

LD39100PU18RY is housed in a thermally enhanced DFN6 (3×3 mm) package with exposed thermal pad connected to GND. The wettable flank feature enables reliable solder joint inspection in automotive production.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A0518PDBVR and ADP125ARHZ-1.8-R7, LD39100PU18RY uniquely combines AEC-Q100 Grade 1, 1 A output, integrated PG flag, and wettable flank DFN6-making it the only drop-in solution for automotive 1.8 V high-current, high-integrity power rails.

Availability

LD39100PU18RY is available at Aetrix Electronics and suitable for automotive infotainment systems, ADAS camera modules, and telematics control units requiring stable component supply with full AEC-Q100 traceability and long-term lifecycle support.

Supply support for LD39100PU18RY 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 automotive-grade LDO portfolio, engineered specifically for post-regulation in harsh environments where low noise, ultra-low I_Q, and functional safety readiness are mandatory.

FAQ

What is the minimum input voltage required for LD39100PU18RY to regulate 1.8 V at 1 A?

The minimum input voltage is 2.0 V, calculated as V_OUT + V_DROP = 1.8 V + 200 mV (typical dropout). At –40 °C to 125 °C, maximum dropout rises to 400 mV, so 2.2 V input ensures regulation across full temperature range. Input below 1.5 V is outside absolute maximum ratings and must be avoided.

Can LD39100PU18RY operate without an external output capacitor?

No. A minimum 1 µF X5R or X7R ceramic capacitor is mandatory on VOUT for loop stability and transient response. Omitting it causes oscillation and potential damage. The capacitor must be placed within 3 mm of VOUT and GND pins, with low-ESR (<150 mΩ) across –40 °C to 125 °C.

How is the Power Good (PG) pin configured for proper operation?

PG is an open-drain output requiring an external pull-up resistor (100 kΩ to 1 MΩ) to VIN or VOUT. It asserts high-impedance when V_OUT ≥ 1.656 V and pulls low when V_OUT ≤ 1.44 V. Leaving PG floating or connecting it directly to VCC without pull-up will disable the function and may cause undefined behavior.

Is LD39100PU18RY pin-compatible with other variants in the LD39100 family?

Yes - all LD39100 fixed-output variants (e.g., LD39100PU25RY, LD39100PU33RY) share identical DFN6 (3×3 mm) pinout and footprint. Only the output voltage and associated internal resistor divider differ; EN, PG, VIN, VOUT, GND, and NC positions are fully compatible for board reuse across voltage options.