LD3985M25R

Overview

The LD3985M25R is a fixed-output low-dropout linear voltage regulator manufactured by STMicroelectronics. It provides a stable 2.5 V output with a maximum continuous current of 150 mA. The device operates from an input voltage range of 2.5 V to 6 V and utilizes a TSOT-23-5 surface-mount package. Key electrical characteristics include a typical quiescent current of 85 µA at no load, ensuring efficient power management in battery-powered applications. The regulator features logic-controlled electronic shutdown, internal thermal and current limiting, and maintains stability when used with low ESR ceramic capacitors.

Feature Summary

• Ultra-low dropout voltage performance for extended battery life
• Logic-controlled electronic shutdown function for standby power reduction
• Compatible with low ESR ceramic output capacitors
• Internal protection against overcurrent and thermal overload

Applications

• Mobile phones and similar battery-powered wireless systems
• Portable information appliances
• Low power consumer electronics requiring stable local regulation

Procurement Notes

Verify the specific suffix 'M25R' corresponds to the 2.5 V fixed output variant within the LD3985 series. Confirm the package type matches the required PCB footprint, typically TSOT-23-5. Ensure compatibility with low ESR ceramic capacitors as specified in the official datasheet to maintain loop stability. Check for RoHS compliance status if required by your manufacturing standards.

Selection Notes

Select this component when a fixed 2.5 V rail is needed with moderate current demands up to 150 mA. It is suitable for designs prioritizing low noise and high power supply rejection ratio (PSRR) over switching regulators. Consider the input voltage headroom requirements relative to the dropout characteristics. Evaluate the need for the shutdown pin functionality to manage system power states effectively.

Part Context

The LD3985 belongs to STMicroelectronics' family of ultra-low drop and low-noise BiCMOS voltage regulators. This series is engineered for efficiency in portable devices, offering minimal ground current consumption that increases only slightly during dropout conditions. The technology supports wide input ranges while maintaining high PSRR down to low input voltages common in battery-operated circuits.

Replacement Considerations

Cross-reference with other LD3985 variants such as LD3985M18R or LD3985M33R for different fixed output voltages. Verify pinout compatibility before substitution. Consult the official datasheet for any updates on automotive grade alternatives like the LDS3985 series if higher reliability ratings are required.