LDO40LPURY

Overview

The LDO40LPURY is a 400 mA low-dropout linear regulator from STMicroelectronics, designed for severe automotive environments. It features an adjustable output voltage range from 2.5 V to 11 V with ±3% total accuracy across line, load, and temperature variations. The device operates with an input voltage up to 38 V and starts at 3.5 V. Key electrical characteristics include a typical quiescent current of 45 µA, ultra-low dropout voltage (36 mV at 100 mA), high PSRR of 70 dB at 1 kHz, and very low noise of 20 µVRMS/VOUT. It includes current limit and thermal shutdown protection.

Feature Summary

• Low quiescent current suitable for battery-connected applications
• Wide input voltage operating range up to 38 V
• Adjustable output voltage from 2.5 V to 11 V
• High precision with ±3% total accuracy

Applications

• Automotive body control modules
• Instruments and clusters
• Automotive LED lighting

Procurement Notes

Verify the specific part number against the manufacturer's official ordering information to confirm the adjustable output configuration and tape-and-reel packaging. Ensure compatibility with AEC-Q100 Grade 1 requirements if used in automotive systems. Cross-reference datasheet revision history for any updates to electrical characteristics or package dimensions before finalizing procurement specifications.

Selection Notes

Select this component when an adjustable output voltage between 2.5 V and 11 V is required with high efficiency under varying load conditions. The wide input voltage range supports applications with significant rail fluctuations, such as cold-crank scenarios. Ensure external capacitors meet stability requirements, specifically ceramic types with appropriate ESR values within the tested stability plan.

Part Context

This device belongs to the LDO40L family of low-dropout regulators. It shares core architectural features with fixed-output variants like the LDO40LPU33RY and LDO40LPU50RY, including the DFN6 package and protection circuits. The primary distinction lies in the adjustable output capability via the ADJ pin, offering design flexibility for non-standard voltage rails compared to fixed versions.

Replacement Considerations

Direct substitutes within the same family include other LDO40L variants with different output configurations, such as LDO40LPU33RY or LDO40LPU50RY, provided the fixed voltage meets system requirements. Verify that any replacement maintains the DFN6 package footprint and wettable flanks for reliable soldering.

FAQ

How is the output voltage adjusted on the LDO40LPURY?

The output voltage is set using an external resistor divider connected between the VOUT and ADJ pins. The internal bandgap reference generates a fixed 1.2 V reference between these terminals.

What is the purpose of the VSENSE pin?

The VSENSE pin allows for remote sensing of the output voltage. It must be connected to the load or directly shorted to the VOUT pin to ensure correct regulation and is not left floating.

Does the LDO40LPURY have an enable function?

Yes, the EN pin controls the device state. Connecting VEN high turns the regulator on, while connecting it low turns it off. An internal pull-up or pull-down is not present, so the pin must not be left floating.