STMicroelectronics LD39150DT25-R

Overview

LD39150DT25-R from STMicroelectronics is a fixed-output 2.5 V, 1.5 A ultra-low-dropout linear regulator in DPAK package, designed for post-regulation after switching converters and low-voltage microprocessor core supplies. It delivers 200 mV typical dropout at full load, 1 mA typical quiescent current under 1.5 A output, ±1.5% output voltage tolerance at 25 °C, and operates across –40 to 125 °C junction temperature.

For engineers reviewing the LD39150DT25-R datasheet, LD39150DT25-R pinout, LD39150DT25-R application, or LD39150DT25-R equivalent, key selection criteria include dropout performance at high load, shutdown current in inhibit mode (<1 µA), ceramic capacitor stability (≥2.2 µF), thermal resistance (R_thJA = 100 °C/W), and logic-controlled enable functionality with defined VIH/VIL thresholds.

Technical Context

The LD39150DT25-R employs a BiCMOS process enabling load-independent quiescent current-critical for battery-backed systems where standby power must remain sub-µA. Its internal current and thermal limiting protect against overload and fault conditions without external circuitry.

It features fast dynamic response to load transients and stable operation with low-ESR ceramic capacitors, eliminating need for tantalum or electrolytic types. The inhibit input (VINH) provides clean ON/OFF control with 2 V threshold for activation and 0.3 V for disable-no internal pull-up/down requires explicit biasing.

Key Specifications

Pinout & Package

LD39150DT25-R is supplied in DPAK (TO-252) package with exposed thermal pad electrically connected to GND. The 5-pin configuration supports input filtering, regulated output delivery, logic-controlled shutdown, and robust thermal management via PCB copper pour.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSM1052-2.5 and TPS7A2025PDBVR, LD39150DT25-R uniquely balances 1.5 A output, 200 mV dropout, and sub-µA shutdown-making it the only choice for thermally constrained, high-current industrial microcontrollers requiring both precision and ruggedness.

Availability

LD39150DT25-R is available at Aetrix Electronics and suitable for microprocessor core supplies, DSP power rails, and post-regulators for switching supplies requiring stable component supply, long-term industrial lifecycle support, and RoHS-compliant DPAK packaging.

Supply support for LD39150DT25-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 LD39150 belongs to ST's high-performance analog LDO portfolio, engineered specifically for low-noise, high-current post-regulation in space-constrained embedded systems where thermal efficiency and voltage accuracy are non-negotiable.

FAQ

What is the minimum input voltage required for LD39150DT25-R to maintain regulation?

The LD39150DT25-R requires a minimum input voltage of 2.5 V to operate, but to sustain 2.5 V output at 1.5 A load, input must be ≥2.7 V due to its 200 mV typical dropout. At lighter loads (e.g., 300 mA), input can drop to 2.54 V (2.5 V + 40 mV). Operation below 2.5 V risks undervoltage lockout or unregulated output.

Can LD39150DT25-R be used with a 1 µF input capacitor and no output capacitor?

No. While a 1 µF ceramic input capacitor is mandatory and sufficient for input filtering, the device requires a minimum 2.2 µF ceramic output capacitor for stability-omitting it causes oscillation or catastrophic failure. The datasheet explicitly states CO ≥2.2 µF is needed, and stability charts (Figures 15–16) define allowable ESR ranges dependent on CO value.

Is the TAB pin on LD39150DT25-R electrically isolated or must it be grounded?

The TAB is electrically connected to GND and must be soldered to a PCB ground plane. It is not isolated-it serves as both thermal conduction path and return path for internal current sources. Leaving it unconnected degrades thermal performance (R_thJA rises from 100 to >150 °C/W) and may cause instability or premature thermal shutdown.

Does LD39150DT25-R support adjustable output voltage configurations?

No. LD39150DT25-R is a fixed 2.5 V output variant. Adjustable versions exist (e.g., LD39150PT-R), but they use different pinouts-specifically, Pin 5 becomes VSENSE (error amplifier input) and require external resistor dividers. The DT25-R variant has Pin 5 internally tied and is not configurable; attempting to modify output voltage will result in incorrect regulation or damage.