STMicroelectronics LD39300DT25-R

Overview

LD39300DT25-R from STMicroelectronics is a 3A ultra-low-dropout linear voltage regulator with fixed 2.5V output, 200mV typical dropout at 3A load, ±1.5% output voltage tolerance at 25°C, and 1.2mA typical quiescent current in active mode. It operates from 2.5V to 6V input and supports logic-controlled shutdown for microprocessor core power supplies in space-constrained industrial and embedded systems.

For engineers reviewing the LD39300DT25-R datasheet, LD39300DT25-R pinout, LD39300DT25-R application, or LD39300DT25-R equivalent, key selection criteria include dropout voltage under full load, thermal shutdown threshold (170°C), stability with ceramic output capacitors ≥4.7µF, inhibit pin interface requirements, and PPAK package thermal resistance (R_thJC = 8°C/W).

Technical Context

The LD39300DT25-R uses BiCMOS process technology to decouple quiescent current from load current-enabling 1.2mA I_Q at 3A load and only 1µA in shutdown. Its error amplifier compares internal 1.22V reference against feedback (not required for fixed versions) to regulate output with fast transient response.

It integrates current limiting (6A short-circuit protection), thermal shutdown (170°C with 10°C hysteresis), and logic-compatible inhibit input (VIH ≥2V, VIL ≤0.3V). Stability is guaranteed with CO ≥4.7µF and ESR within defined region per Figure 14/15-not dependent on external compensation.

Key Specifications

Pinout & Package

LD39300DT25-R is housed in a thermally enhanced PPAK (Power Package) with exposed thermal pad, offering R_thJC = 8°C/W for efficient heat transfer to PCB copper. The 5-pin configuration supports compact layout with dedicated input, output, ground, inhibit, and sense (N.C. on fixed versions) terminals.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSM1052-2.5 and MCP1826-2502E/DB, LD39300DT25-R uniquely combines 200mV dropout, 1µA shutdown current, and 170°C thermal shutdown with hysteresis-making it optimal for thermally aggressive, dynamically loaded applications where both efficiency and fault resilience are critical.

Availability

LD39300DT25-R is available at Aetrix Electronics and suitable for microprocessor core supplies, DSP power rails, and industrial sensor interfaces requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for LD39300DT25-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 family targeting low-noise, high-current power management in space-constrained embedded systems-emphasizing ultra-low dropout, ceramic-capacitor compatibility, and robust thermal protection.

FAQ

What is the minimum output capacitance required for stability?

The LD39300DT25-R requires a minimum 4.7µF ceramic output capacitor with ESR within the stability region shown in Figures 14 and 15 of the datasheet. Using lower capacitance or out-of-range ESR risks oscillation during load transients-even with proper PCB layout. X7R or X5R dielectrics are recommended for stable performance across temperature.

Can the inhibit pin be left unconnected?

No-the inhibit pin (VINH) must never be left floating because it has no internal pull-up or pull-down. Leaving it unconnected may cause unpredictable ON/OFF behavior due to noise coupling. If shutdown control is unused, tie VINH directly to VIN to maintain continuous operation with minimal added current (<1µA).

Is an input capacitor mandatory?

Yes-a minimum 1µF ceramic input capacitor is mandatory and must be placed within 1cm of the VIN pin, connected directly to the GND pin with a dedicated low-impedance trace. This capacitor suppresses high-frequency noise from upstream sources and prevents instability caused by source inductance; omitting it risks oscillation or poor PSRR performance.

How does thermal performance differ between PPAK and DPAK packages?

Both PPAK and DPAK packages share identical R_thJA = 100°C/W (still-air), but PPAK offers R_thJC = 8°C/W versus DPAK's 8°C/W-identical junction-to-case resistance. The real advantage lies in PPAK's smaller footprint (6×6.5mm vs. DPAK's ~10×6.5mm) and superior thermal pad soldering reliability, enabling better heat transfer to inner-layer copper planes in dense PCB layouts.