STMicroelectronics LDO40LPU33RY

Overview

LDO40LPU33RY from STMicroelectronics is a 400 mA, 3.3 V fixed-output low-dropout linear regulator in DFN6 (3×3 mm, wettable flanks) package, AEC-Q100 qualified for automotive use. It operates from 3.5 V to 38 V input, delivers ±3% output accuracy over –40 °C to +125 °C, and maintains ultra-low dropout (140 mV @ 400 mA) and quiescent current (45 µA typ. at no load), enabling always-on battery-connected modules like body control units.

For engineers reviewing the LDO40LPU33RY datasheet, LDO40LPU33RY pinout, LDO40LPU33RY application, or LDO40LPU33RY equivalent, key selection criteria include startup voltage (3.5 V), remote sensing capability via VSENSE, thermal shutdown (175 °C), enable logic thresholds (VEN-H = 2.7 V), and PSRR (70 dB @ 1 kHz) for noise-sensitive automotive power rails.

Technical Context

The LDO40LPU33RY uses a P-channel MOSFET pass element enabling low dropout and cold-crank operation down to 3.5 V input. Its bandgap reference (1.2 V typ.) and internal error amplifier deliver tight line/load regulation (0.002 %/V, 0.002 %/mA) and stable output under wide temperature and load variation.

Integrated protection includes current limiting (~1.5 A short-circuit current), thermal shutdown with 25 °C hysteresis, and enable-controlled sequencing. The VSENSE pin supports remote feedback for improved load regulation, while EN pin requires explicit high/low biasing-no internal pull-up/pull-down.

Key Specifications

Pinout & Package

Package: DFN6 (3 × 3 mm, 0.85 mm height) with wettable flanks for automated optical inspection (AOI) of solder joints. Exposed thermal pad (TAB) must be connected to GND for thermal performance (R_thJC = 5 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLD5098ELXUMA1 and TLV73333PDBVR, the LDO40LPU33RY uniquely combines AEC-Q100 Grade 1 qualification, VSENSE-enabled remote sensing, and 3.5 V cold-crank startup - making it the sole choice for safety-compliant, high-reliability automotive 3.3 V system rails.

Availability

LDO40LPU33RY is available at Aetrix Electronics and suitable for automotive body electronics, instrument clusters, and LED lighting systems requiring stable component supply across extended temperature and long product lifecycles.

Supply support for LDO40LPU33RY 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, specializing in automotive, industrial, and power management solutions.

The LDO40L series was developed specifically for harsh automotive environments, emphasizing ultra-low IQ, wide VIN range, and robust protection - targeting permanent-battery-connected modules such as BCMs and telematics units.

FAQ

Is the LDO40LPU33RY pin-compatible with other ST LDO40L variants?

Yes - all LDO40L DFN6 variants (e.g., LDO40LPURY, LDO40LPU50RY) share identical pinout and footprint. The ADJ/NC pin is unconnected in fixed-output versions, and VSENSE must always be tied to VOUT or the load. No layout change is needed when switching between 3.3 V, 5.0 V, or adjustable versions.

Can the VSENSE pin be left unconnected?

No - VSENSE must never be left floating. In fixed-output versions, it must be connected directly to VOUT (Pin 4) using a low-impedance trace. Leaving it open risks output instability and violates the device's internal feedback loop integrity, potentially causing regulation failure or oscillation.

What is the minimum input capacitor required for stability?

A minimum 1 µF X5R/X7R ceramic capacitor is required at VIN, placed as close as possible to Pin 3 and returned to clean analog ground. ST validates stability with ESR between 5 mΩ and 12 Ω; lower ESR capacitors (e.g., <2 mΩ) may require series resistance to maintain phase margin per Figure 27 in DS12711.

Does the LDO40LPU33RY support reverse polarity protection?

No - the device has no built-in reverse polarity protection. If reverse battery connection is possible in the application, an external Schottky diode (anode to VIN, cathode to input cap) or ideal diode controller must be added. Reverse voltage beyond –0.3 V on VIN will damage the part per absolute maximum ratings.