STMicroelectronics LDO40LPU50RY

Overview

LDO40LPU50RY from STMicroelectronics is a 400 mA, 5.0 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 LDO40LPU50RY datasheet, LDO40LPU50RY pinout, LDO40LPU50RY application, or LDO40LPU50RY 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 LDO40LPU50RY uses a P-channel MOSFET pass element with internal bandgap reference (1.2 V typ.) and precision error amplifier to regulate output voltage. Its architecture supports both local and remote sensing via dedicated VSENSE pin (Pin 5), enabling accurate regulation under PCB trace IR drop.

It integrates current limiting (~1.5 A short-circuit current) and thermal shutdown with 25 °C hysteresis, and features an active-high enable input (EN, Pin 2) with no internal pull-up/pull-down-requiring external biasing to avoid floating states. The device enters dropout when VIN falls below VOUT + VDROP (e.g., <5.14 V @ 400 mA).

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 TLD5098EL and TLV73350PDBVR, LDO40LPU50RY uniquely combines AEC-Q100 Grade 1 qualification, VSENSE-based remote sensing, 20 µV_RMS/V_OUT noise, and wettable flanks-making it the only option qualified for safety-critical, high-reliability automotive power nodes requiring traceable solder joint inspection.

Availability

LDO40LPU50RY is available at Aetrix Electronics and suitable for automotive body control modules, instrument clusters, LED lighting systems, and telematics units requiring stable component supply across extended temperature and long product lifecycles.

Supply support for LDO40LPU50RY 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 power management applications.

LDO40LPU50RY belongs to the LDO40L family of automotive-grade linear regulators engineered specifically for harsh-environment battery-connected modules where ultra-low quiescent current, wide input range, and AEC-Q100 reliability are mandatory.

FAQ

What is the minimum input voltage required for regulation at 5.0 V output?

The LDO40LPU50RY requires a minimum input voltage of 5.14 V to maintain regulation at 400 mA load (VOUT + VDROP = 5.0 V + 140 mV). At lighter loads, dropout decreases-for example, 5.036 V is sufficient at 100 mA (5.0 V + 36 mV). Startup is guaranteed down to 3.5 V, but full regulation begins only above VOUT + VDROP.

Can the VSENSE pin be left unconnected in a standard layout?

No. The VSENSE pin (Pin 5) must never be left floating. In local-regulation configurations, it must be shorted directly to VOUT (Pin 4) using a low-inductance trace. For remote sensing, it connects to the load-side of the output trace to compensate for voltage drop-ensuring precise regulation at the point of load.

Does LDO40LPU50RY support reverse polarity protection?

No. The LDO40LPU50RY does not integrate reverse-polarity protection. External protection-such as a series Schottky diode or ideal diode controller-is required if the input may experience reversed battery connection, as absolute maximum rating for VIN is –0.3 V.

How does the enable pin behave during power-up sequencing?

The EN pin (Pin 2) has no internal pull-up or pull-down. To ensure predictable startup, it must be actively driven to ≥2.7 V (logic high) before VIN reaches 3.5 V. If left uncontrolled, undefined EN state may cause erratic turn-on or delayed regulation, risking system initialization failure in automotive boot sequences.