STMicroelectronics LDO40LPURY

Overview

LDO40LPURY from STMicroelectronics is an AEC-Q100 qualified 400 mA adjustable-output LDO regulator in DFN6 (3×3 mm, wettable flanks) package, featuring 45 µA quiescent current, 38 V max input voltage, 36 mV dropout at 100 mA, and ±3% total output accuracy over line/load/temperature. It serves as a primary power rail regulator in automotive body control modules requiring ultra-low standby consumption.

For engineers reviewing the LDO40LPURY datasheet, LDO40LPURY pinout, LDO40LPURY application, or LDO40LPURY equivalent, key selection criteria include startup voltage (3.5 V), remote sensing capability via VSENSE, enable logic thresholds (VEN-H = 2.7 V), thermal shutdown (175 °C), and compatibility with ceramic output capacitors ≥1 µF.

Technical Context

The LDO40LPURY 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.) feeds an error amplifier that regulates output via external resistor divider on ADJ pin, supporting 2.5–11 V adjustable output.

It integrates current limiting (~1.5 A short-circuit current), thermal shutdown with 25 °C hysteresis, and an enable input with no internal pull-up/pull-down-requiring explicit external biasing. The VSENSE pin enables Kelvin sensing for improved load regulation in high-current or noisy PCB layouts.

Key Specifications

Pinout & Package

Package: DFN6 (3 × 3 mm, 0.85 mm height) with wettable flanks for automated optical solder-joint inspection. 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 adjustable LDO regulator applications.

Compared with TLD1114-1EP and NCP1117DTAR, LDO40LPURY uniquely combines AEC-Q100 qualification, 400 mA adjustable output, VSENSE capability, and sub-50 µA quiescent current-making it the only option meeting full automotive BCM and cluster requirements.

Availability

LDO40LPURY 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 voltage ranges.

Supply support for LDO40LPURY 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 LDO40L series was developed specifically for harsh automotive environments, targeting permanent-battery-connected ECUs needing ultra-low IQ, wide VIN tolerance, and robust protection features.

FAQ

What is the minimum input voltage required for regulation with LDO40LPURY?

The minimum input voltage is 3.5 V regardless of output setting, enabling operation during automotive cold-crank events. Full regulation (±3% accuracy) requires VIN ≥ VOUT + 1 V or 5 V, whichever is greater-e.g., 6 V for a 5 V output. Below this, the device enters dropout but maintains tracking behavior useful for diagnostics.

How should the VSENSE pin be connected in a typical layout?

VSENSE must never be left floating. For best accuracy, route it directly to the load-side of the output capacitor (remote sensing), especially when PCB traces exceed 50 mΩ. If remote sensing is unnecessary, short VSENSE to VOUT at the regulator's output pad-never at the load-to avoid instability from loop gain errors.

Can LDO40LPURY be used with ceramic output capacitors smaller than 1 µF?

No. The control loop is optimized for ≥1 µF ceramic capacitors (X5R/X7R) with ESR between 5 mΩ and 12 Ω. Using smaller values risks oscillation or poor transient response, as confirmed by stability testing in Figure 27 of DS12711. A 4.7 µF capacitor is recommended for optimal dynamic performance.

What happens during thermal shutdown, and how does recovery work?

When junction temperature reaches 175 °C, the device shuts down output and disables the pass transistor. It remains off until junction temperature falls to ~150 °C (25 °C hysteresis), then automatically resumes regulation. This cycle prevents permanent damage but requires proper PCB copper area and thermal vias to limit power dissipation per Equation (2) in Section 6.4.