STMicroelectronics LD39300DT18-R

Overview

LD39300DT18-R from STMicroelectronics is a 3A ultra-low-dropout linear voltage regulator with fixed 1.8V output, 200mV typical dropout at 3A load, ±1.5% output voltage tolerance at 25°C, and logic-controlled shutdown. It operates from 2.5V to 6V input and targets low-voltage microprocessor core supplies where low noise, fast transient response, and ceramic-capacitor stability are critical.

For engineers reviewing the LD39300DT18-R datasheet, LD39300DT18-R pinout, LD39300DT18-R application, or LD39300DT18-R equivalent, this page delivers verified electrical specs, DPAK package details, thermal and quiescent current behavior, inhibit control timing, and real-world use cases in DSP power domains and post-regulation of switching supplies.

Technical Context

The LD39300DT18-R uses a BiCMOS process to decouple quiescent current from load-maintaining 1.2mA typ. at 3A while dropping to ≤1µA in shutdown. Its error amplifier compares internal 1.22V reference against feedback (not required for fixed versions) and drives a PMOS pass transistor with low R_DS(on) to achieve 40mV dropout at 600mA.

Stability is guaranteed with ≥4.7µF ceramic output capacitance and ESR <100mΩ; line/load transients settle within 20µs due to high loop bandwidth. The inhibit pin (VINH) requires external logic-level drive-no internal pull-up/down-and triggers fast current limiting before thermal shutdown at 170°C.

Key Specifications

Pinout & Package

LD39300DT18-R is housed in a thermally enhanced DPAK (TO-252-3) package with exposed drain pad for PCB heat sinking. R_thJA = 100°C/W, R_thJC = 8°C/W. Pin 1 = VINH (inhibit), Pin 2 = GND, Pin 3 = VO, Pin 4 = VI.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSM1083-1.8 and MCP1826-1802E/DB, LD39300DT18-R offers superior dropout (200mV vs. ≥250mV), lower shutdown current (≤1µA vs. ≥2.5µA), and integrated inhibit control-making it optimal for thermally demanding, battery-sensitive, and dynamically controlled processor power rails.

Availability

LD39300DT18-R is available at Aetrix Electronics and suitable for microprocessor core supplies, DSP power rails, and post-regulation of switching supplies requiring stable component supply, long-term lifecycle support, and automotive-grade temperature range (-40°C to 125°C).

Supply support for LD39300DT18-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, and ultra-low-dropout applications in advanced digital systems-including microprocessors, DSPs, FPGAs, and mixed-signal SoCs.

FAQ

What is the minimum input voltage required for LD39300DT18-R to maintain 1.8V output at 3A?

The minimum input voltage is calculated as VO + VDROP = 1.8V + 0.2V = 2.0V. However, per datasheet specifications, the device requires VI ≥ 2.5V for guaranteed operation across temperature and process variation. At 2.5V input, dropout margin is 0.7V-ensuring regulation stability even at worst-case 400mV dropout.

Can LD39300DT18-R be used with aluminum polymer capacitors instead of ceramic?

No-aluminum polymer capacitors are not recommended. The LD39300DT18-R's stability region (Figure 14/15) is defined for ceramic capacitors with ESR <100mΩ and CO ≥4.7µF. Aluminum polymer caps typically exceed 100mΩ ESR at low frequencies and may cause oscillation or poor transient response.

Is the inhibit pin (VINH) compatible with 1.8V logic levels?

No-VINH requires ≥2.0V to guarantee ON mode and ≤0.3V to guarantee OFF mode. A 1.8V logic high falls below the 2.0V threshold and may result in undefined or partial turn-on. Level-shifting circuitry or a 3.3V GPIO is required for reliable inhibit control.

Does LD39300DT18-R require an external resistor divider for 1.8V output?

No-the "DT" suffix denotes the fixed-output version. Pin 5 (VSENSE/N.C.) is not connected internally for LD39300DT18-R; no external feedback network is needed. Only adjustable versions (e.g., LD39300PT-R) require R1/R2 to set VO = 1.22V × (1 + R1/R2).