STMicroelectronics LD39300PT33-R

Overview

LD39300PT33-R from STMicroelectronics is a 3.3V fixed-output ultra-low-dropout linear regulator in PPAK-5 package, delivering up to 3A output current with 200mV typical dropout at full load, 1.2mA quiescent current in active mode, and logic-controlled shutdown. It operates from 2.5V–6V input and targets microprocessor core power supply applications requiring tight voltage tolerance (±1.5% @ 25°C) and fast transient response.

For engineers reviewing the LD39300PT33-R datasheet, LD39300PT33-R pinout, LD39300PT33-R application, or LD39300PT33-R equivalent, key selection criteria include guaranteed 3A output capability, ceramic-capacitor stability (≥4.7µF), inhibit-controlled enable/disable functionality, thermal shutdown at 170°C, and operation across –40°C to +125°C junction temperature range.

Technical Context

The LD39300PT33-R employs a BiCMOS process enabling load-independent quiescent current-critical for battery-backed or low-power standby systems. Its error amplifier drives an internal pass transistor with integrated current limiting and thermal foldback, supporting stable regulation under rapid load steps (e.g., 10mA → 3A in 20µs).

It features a dedicated inhibit input (VINH) with defined thresholds (≤0.3V for OFF, ≥2V for ON), no internal pull-up/down, requiring external biasing. Output voltage is fixed at 3.3V; the VSENSE/N.C. pin is not connected on fixed versions, distinguishing it from adjustable variants.

Key Specifications

Pinout & Package

LD39300PT33-R is housed in a thermally enhanced PPAK-5 surface-mount package (5-pin, exposed thermal pad), optimized for PCB heat dissipation with R_thJC = 8°C/W. The package complies with ECOPACK® environmental standards and JEDEC JESD97 marking requirements.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSM1033W-3.3V and NCP1117DT33T5G, the LD39300PT33-R delivers 2× higher output current, 40% lower dropout, and integrated logic-controlled shutdown-making it the preferred choice for compact, high-efficiency 3.3V power domains in modern embedded processors and automotive body electronics.

Availability

LD39300PT33-R is available at Aetrix Electronics and suitable for microprocessor core supply, DSP power rail, and industrial sensor hub applications requiring stable component supply, consistent parametric performance, and long-term production continuity.

Supply support for LD39300PT33-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 silicon solutions for automotive, industrial, and consumer markets since 1987.

The LD39300 belongs to ST's high-performance LDO regulator product line, engineered specifically for low-voltage, high-current digital power delivery where ultra-low dropout, ceramic-capacitor stability, and fast transient response are critical design requirements.

FAQ

What is the minimum input voltage required for stable 3.3V output at 3A?

The LD39300PT33-R requires VI ≥ VO + VDROP. With 200mV typical dropout at 3A, the minimum functional input is 3.5V. At worst-case 400mV dropout (per datasheet max), 3.7V input ensures regulation across temperature and process variation. Below this, output voltage drops linearly with input.

Can the LD39300PT33-R be used without the inhibit pin connected?

No-the inhibit pin (VINH) has no internal pull-up or pull-down. Leaving it floating risks undefined operation and potential oscillation. If unused, VINH must be tied directly to VI to guarantee continuous ON mode. A 10kΩ resistor to VI is acceptable but direct connection is preferred for lowest leakage.

Which ceramic capacitor dielectric and case size are recommended for output stability?

X7R or X5R dielectrics in 0805 or 1206 case sizes are validated for stability with ≥4.7µF capacitance. Avoid Y5V due to excessive capacitance drift over temperature and bias. The ESR must fall within the region shown in Figure 14 of the datasheet-typically 5–50mΩ for 4.7µF parts.

Does the LD39300PT33-R require a heatsink in a 3A, 5V-in application?

With R_thJA = 100°C/W and 600mW typical power dissipation (3A × 0.2V dropout), junction temperature rise is ~60°C above ambient. At 85°C ambient, TJ ≈ 145°C-exceeding the 125°C limit. A 250mm² copper pour (2oz) under the thermal pad reduces R_thJA to ~45°C/W, keeping TJ < 120°C. Heatsinks are not required if PCB thermal design meets this.