STMicroelectronics LD39150DT33-R

Overview

LD39150DT33-R from STMicroelectronics is a fixed-output 3.3 V ultra-low-dropout linear regulator delivering 1.5 A guaranteed output current with 200 mV typical dropout at full load, 1 mA typical quiescent current in active mode, and 1 µA max shutdown current. It operates from 2.5 V to 6 V input, supports logic-controlled shutdown, and is stable with ceramic output capacitors - ideal for powering low-voltage microprocessors and DSPs in space-constrained industrial and embedded systems.

For engineers reviewing the LD39150DT33-R datasheet, LD39150DT33-R pinout, LD39150DT33-R application, or LD39150DT33-R equivalent, key selection criteria include dropout voltage under 1.5 A load, thermal shutdown threshold (170 °C), ±1.5% output tolerance at 25 °C, fast transient response, and compatibility with DFN6 (3×3 mm), DPAK, or PPAK packages.

Technical Context

The LD39150DT33-R uses a BiCMOS process enabling load-independent quiescent current - critical for battery-backed and always-on subsystems. Its internal current and thermal limiting protect against overload and junction overheating, while the inhibit pin (VINH) provides clean ON/OFF control with defined thresholds (≥2 V for ON, ≤0.3 V for OFF).

It features 65 dB supply voltage rejection at 120 Hz and 100 µV_RMS output noise (10 Hz–100 kHz), making it suitable for noise-sensitive analog rails. Stability is ensured with ≥2.2 µF ceramic output capacitance and proper PCB layout - no external compensation required.

Key Specifications

Pinout & Package

LD39150DT33-R is available in DFN6 (3 × 3 mm), DPAK, and PPAK packages. This specific order code uses the DFN6 package - a thermally enhanced, leadless surface-mount outline with exposed thermal pad electrically connected to GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A4700RGWR and NCP1117ST33T3G, LD39150DT33-R delivers 50% higher output current, half the dropout voltage, and one-sixth the active-mode quiescent current - making it superior for high-efficiency, high-transient, and thermally constrained applications.

Availability

LD39150DT33-R is available at Aetrix Electronics and suitable for microprocessor core supplies, DSP power rails, and industrial PLC I/O modules requiring stable component supply, automotive-grade temperature resilience, and low-noise regulation.

Supply support for LD39150DT33-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 LDO portfolio targeting low-power, high-transient embedded systems - engineered specifically for microprocessor, DSP, and FPGA auxiliary rail applications demanding ultra-low dropout and ceramic-capacitor stability.

FAQ

What is the minimum input voltage required for LD39150DT33-R to maintain regulation at 1.5 A?

The minimum input voltage is calculated as VO + VDROP = 3.3 V + 0.2 V = 3.5 V (typical). At worst-case conditions (125 °C, 1.5 A), dropout may reach 400 mV, so VI ≥ 3.7 V is recommended for guaranteed regulation across temperature and load extremes.

Can LD39150DT33-R be used with a 2.2 µF X5R ceramic capacitor on the output?

Yes - the datasheet specifies ≥2.2 µF ceramic output capacitance is sufficient for stability. However, the capacitor's ESR must fall within the stability region shown in Figure 15 (100 kHz), typically 5–30 mΩ for X5R types; verify ESR vs. temperature to ensure margin across -40 to 125 °C.

Is the 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. Leaving it unsoldered increases R_thJA from 40 °C/W to >100 °C/W, risking thermal shutdown at <500 mA. ST recommends connecting it to a ≥100 mm² internal or bottom-layer copper pour with ≥4 thermal vias.

Does LD39150DT33-R require an external pull-up on the VINH pin if unused?

No - VINH must not be left floating, but tying it directly to VI (input voltage) is sufficient to maintain ON state. An external pull-up resistor is unnecessary and adds leakage risk; direct connection ensures robust logic-high assertion across voltage and temperature ranges.