STMicroelectronics LD39150PT33-R

Overview

LD39150PT33-R from STMicroelectronics is a fixed-output 3.3 V ultra-low-dropout linear regulator (LDO) built on BiCMOS technology, delivering up to 1.5 A output current with 200 mV typical dropout at full load and stable operation with ceramic output capacitors ≥2.2 µF. It features logic-controlled shutdown (inhibit pin), ±1.5% output voltage tolerance at 25 °C, and operates across -40 to 125 °C for microprocessor core power in space-constrained embedded systems.

For engineers reviewing the LD39150PT33-R datasheet, LD39150PT33-R pinout, LD39150PT33-R application, or LD39150PT33-R equivalent, this page delivers verified electrical specs, thermal performance data, package-specific layout guidance, and real-world use cases for low-noise, high-efficiency post-regulation in battery-powered and automotive-qualified designs.

Technical Context

The LD39150PT33-R uses a BiCMOS architecture enabling ultra-low quiescent current (1 mA typ. @ 1.5 A) independent of load, unlike conventional bipolar LDOs. Its internal error amplifier compares output voltage against a 1.22 V reference, driving a PMOS pass transistor with fast transient response to line/load steps.

It integrates thermal shutdown (170 °C trip, 10 °C hysteresis), current limiting (~3 A short-circuit protection), and an inhibit input (VIH ≥ 2 V / VIL ≤ 0.3 V) that reduces quiescent current to ≤1 µA in off mode - critical for always-on subsystems requiring <1 µA standby leakage.

Key Specifications

Pinout & Package

LD39150PT33-R is supplied in the DFN6 (3 × 3 mm) package with wettable flank leads, optimized for automated optical inspection (AOI) and thermal performance via exposed thermal pad (TAB) connected to GND. The 6-pin configuration supports compact two-layer PCB layouts with minimal decoupling trace length.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B332MR-G and ADM7172ACPZ-3.3-R7, the LD39150PT33-R uniquely balances 1.5 A capability, sub-1 µA shutdown, integrated inhibit, and DFN6 thermal performance - making it optimal for thermally constrained, battery-sensitive applications requiring both high efficiency and robust fault protection.

Availability

LD39150PT33-R is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, medical wearable sensor hubs, and edge AI camera nodes requiring stable component supply with guaranteed long-term availability and full ECOPACK® compliance.

Supply support for LD39150PT33-R 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 microcontrollers, power management ICs, sensors, and analog components for industrial, automotive, and consumer markets.

The LD39150 series belongs to ST's high-performance LDO portfolio, engineered specifically for low-voltage, high-current post-regulation in microprocessor and DSP power domains where ultra-low dropout, fast transient response, and ceramic-capacitor compatibility are mandatory.

FAQ

What is the minimum input voltage required for LD39150PT33-R to maintain regulation?

The LD39150PT33-R requires a minimum input voltage of 3.5 V to sustain 3.3 V output at 1.5 A load, based on its 200 mV typical dropout voltage. At lighter loads (e.g., 300 mA), dropout drops to 40 mV, allowing regulation down to 3.34 V input. Operation below VI = VO + VDROP violates specification and risks output collapse.

Can LD39150PT33-R be used without the inhibit pin connected?

No - the VINH pin must not be left floating, as it has no internal pull-up or pull-down. For always-on operation, connect VINH directly to VI (input voltage). Leaving it unconnected risks undefined enable state, intermittent output, or increased leakage due to noise coupling into the high-impedance CMOS input.

Is an input capacitor mandatory, and what type is recommended?

Yes - a minimum 1 µF ceramic capacitor (X5R/X7R) is mandatory at the VI pin, placed ≤1 cm from the pin and returned directly to the GND pin (not chassis or digital ground). This suppresses high-frequency noise and prevents oscillation during fast load transients; larger values improve ripple rejection but do not harm stability.

How does thermal performance differ between DFN6 and PPAK packages for LD39150PT33-R?

The DFN6 (3 × 3 mm) package has RthJA = 40 °C/W with PCB ground plane heatsink, while PPAK and DPAK have RthJA = 100 °C/W. This means the DFN6 can dissipate ~2.5× more power before reaching 125 °C junction temperature - critical for 1.5 A operation in compact enclosures without forced airflow or external heatsinks.