STMicroelectronics LD39150PU33R

Overview

LD39150PU33R from STMicroelectronics is a fixed 3.3 V ultra-low-dropout linear regulator in DFN6 (3 × 3 mm) package, delivering up to 1.5 A output current with 200 mV typical dropout at full load, 1 mA typical quiescent current in active mode, and ±1.5% output voltage tolerance at 25 °C. It serves as a post-regulator for switching supplies and primary power source for low-voltage microprocessors and DSPs in automotive and industrial control systems.

For engineers reviewing the LD39150PU33R datasheet, LD39150PU33R pinout, LD39150PU33R application, or LD39150PU33R equivalent, key selection criteria include dropout voltage under 1.5 A load, thermal shutdown threshold at 170 °C, stability with 2.2 µF ceramic output capacitor, and logic-controlled inhibit functionality with 2 V turn-on threshold.

Technical Context

The LD39150PU33R employs a BiCMOS process enabling load-independent quiescent current-1 mA typ. at 1.5 A load-and fast dynamic response to line/load transients. Its internal error amplifier uses VSENSE feedback (pin 5 on DFN6) tied to VO for fixed versions, while ADJ variants use that pin as reference input.

It integrates thermal shutdown (170 °C trip, 10 °C hysteresis), short-circuit protection (3 A limit), and current limiting with 15 µs turn-off/turn-on delay. The inhibit pin (VINH, pin 2) controls ON/OFF state with TTL-compatible thresholds: ≥2 V for ON, ≤0.3 V for OFF; no internal pull-up/down requires explicit biasing.

Key Specifications

Pinout & Package

LD39150PU33R is housed in a thermally enhanced DFN6 (3 × 3 mm) package with exposed thermal pad (TAB) electrically connected to GND. The 6-pin configuration supports compact layout and efficient heat dissipation via PCB ground plane.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B332MR-G and BD39150GUL, LD39150PU33R uniquely combines 200 mV dropout at 1.5 A, integrated inhibit, and automotive-grade thermal shutdown-making it optimal for high-efficiency, safety-aware embedded power rails.

Availability

LD39150PU33R is available at Aetrix Electronics and suitable for microprocessor core supplies, DSP power rails, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LD39150PU33R 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 LD39150 belongs to ST's high-performance LDO portfolio targeting low-power, high-reliability embedded systems-specifically engineered for microprocessor and DSP power delivery where ultra-low dropout, fast transient response, and thermal resilience are critical.

FAQ

What is the minimum input voltage required for LD39150PU33R to maintain regulation at 1.5 A?

The LD39150PU33R requires VI ≥ VO + VDROP = 3.3 V + 0.2 V = 3.5 V minimum to sustain 1.5 A output current while remaining in regulation. At lower input voltages, the device enters dropout and output voltage drops linearly with input.

Can LD39150PU33R operate without an input capacitor?

No. A minimum 1 µF ceramic input capacitor must be placed ≤1 cm from the VI pin and connected directly to GND. Omitting it risks instability, increased noise coupling, and potential damage during input voltage transients due to parasitic inductance.

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

Yes. The TAB is electrically connected to GND and serves as the primary thermal path. It must be fully soldered to a dedicated PCB ground plane with ≥4 thermal vias (0.3 mm diameter) to achieve the specified R_thJA of 40 °C/W and prevent thermal shutdown under 1.5 A load.

Does LD39150PU33R require external resistors to set output voltage?

No. LD39150PU33R is a fixed-output variant-its 3.3 V regulation is factory-trimmed and does not use external feedback resistors. Only adjustable versions (e.g., LD39150PU-R) require R1/R2 divider networks connected to the VSENSE/ADJ pin.